Articles in JSON/article 17.json

{"lines":[{"page":1,"text":"molecules","rect":[74.43930053710938,71.11058044433594,174.35299861995279,53.74262237548828]},{"page":1,"text":"Article","rect":[35.624473571777347,110.08108520507813,63.46699251461706,102.68669891357422]},{"page":1,"text":"Dielectric Spectroscopy Analysis of Liquid Crystals Recovered","rect":[35.983306884765628,133.53884887695313,547.7273125962051,115.89372253417969]},{"page":1,"text":"from End-of-Life Liquid Crystal Displays","rect":[35.983306884765628,152.34793090820313,375.49094247989378,134.7028045654297]},{"page":1,"text":"Ana Barrera 1, Corinne Binet 1, Frédéric Dubois 2 , Pierre-Alexandre Hébert 3, Philippe Supiot 1,","rect":[35.59548568725586,180.72412109375,485.3065423003243,169.48658752441407]},{"page":1,"text":"Corinne Foissac 1 and Ulrich Maschke 1,*","rect":[35.983306884765628,190.86534118652345,222.82502996521965,182.0263214111328]},{"page":1,"text":"1","rect":[167.18743896484376,217.48570251464845,170.17485329546265,213.32968139648438]},{"page":1,"text":"\u0001\u0002\u0003\u0001\u0004\u0005\u0006\u0007\b","rect":[55.490325927734378,372.2783508300781,83.48178633759309,366.4979553222656]},{"page":1,"text":"\u0001","rect":[86.24980163574219,373.0,86.33441740452139,372.0]},{"page":1,"text":"\u0001\u0002\u0003\u0004\u0005\u0006\u0007","rect":[55.490325927734378,380.7819519042969,82.68396879051194,373.82977294921877]},{"page":1,"text":"Citation:","rect":[35.983306884765628,396.62579345703127,63.66342571426497,391.5960388183594]},{"page":1,"text":"Barrera, A.; Binet, C.;","rect":[67.98545837402344,397.5732421875,132.69323375869858,391.57513427734377]},{"page":1,"text":"Dubois, F.; Hébert, P.-A.; Supiot, P.;","rect":[35.983306884765628,410.3772888183594,143.48334911514389,403.36907958984377]},{"page":1,"text":"Foissac, C.; Maschke, U. Dielectric","rect":[35.983306884765628,421.39898681640627,141.00881108513617,415.282470703125]},{"page":1,"text":"Spectroscopy Analysis of Liquid","rect":[35.983306884765628,434.2170104980469,135.73907312071243,427.180908203125]},{"page":1,"text":"Crystals Recovered from End-of-Life","rect":[35.983306884765628,446.12939453125,149.08075333772113,439.0932922363281]},{"page":1,"text":"Liquid Crystal Displays. Molecules","rect":[35.983306884765628,458.04278564453127,141.67753867189433,450.97186279296877]},{"page":1,"text":"2021, 26, 2873.","rect":[35.983306884765628,469.0634460449219,79.55004528213607,463.12109375]},{"page":1,"text":"https://doi.org/","rect":[83.87178802490235,469.9551696777344,136.17892121409313,462.9330139160156]},{"page":1,"text":"10.3390/molecules26102873","rect":[35.63446807861328,480.7250671386719,121.34455162384244,474.84539794921877]},{"page":1,"text":"Academic Editors: Viorel Circu,","rect":[35.711429595947269,504.0,133.4317896669017,498.701171875]},{"page":1,"text":"Doina Manaila-Maximean and","rect":[35.98330307006836,515.8035278320313,130.26717981016555,510.613525390625]},{"page":1,"text":"Valery A. Loiko","rect":[35.732421875,529.5480346679688,84.03147730194688,522.52587890625]},{"page":1,"text":"Received: 15 April 2021","rect":[35.98330307006836,553.3899536132813,108.70026451446744,546.3817138671875]},{"page":1,"text":"Accepted: 11 May 2021","rect":[35.711429595947269,565.3162231445313,106.97850853302212,558.2940673828125]},{"page":1,"text":"Published: 12 May 2021","rect":[35.98330307006836,577.2296142578125,109.17424827911587,570.2074584960938]},{"page":1,"text":"Publisher’s Note: MDPI stays neutral","rect":[35.98330307006836,602.5767822265625,153.0172960433673,595.5546264648438]},{"page":1,"text":"with regard to jurisdictional claims in","rect":[35.69044494628906,614.4901733398438,153.0190128631018,607.468017578125]},{"page":1,"text":"published maps and institutional affil-","rect":[35.77440643310547,626.388671875,154.17643863611773,619.3665161132813]},{"page":1,"text":"iations.","rect":[35.983306884765628,636.4827880859375,58.35882976699934,631.564453125]},{"page":1,"text":"Copyright:","rect":[35.983306884765628,690.9807739257813,70.25758007217513,684.1188354492188]},{"page":1,"text":"©","rect":[74.6893539428711,689.2530517578125,79.8963673953077,684.2163696289063]},{"page":1,"text":"2021","rect":[84.32965087890625,689.2670288085938,98.27078300811978,684.2999267578125]},{"page":1,"text":"by","rect":[102.70406341552735,691.0991821289063,110.43441966499013,684.0770263671875]},{"page":1,"text":"Licensee","rect":[35.98330307006836,701.0609741210938,62.394779216627387,696.226318359375]},{"page":1,"text":"MDPI,","rect":[67.08596801757813,701.1306762695313,87.37728527237045,696.226318359375]},{"page":1,"text":"Basel,","rect":[92.07544708251953,701.0609741210938,109.885235101472,695.9894409179688]},{"page":1,"text":"This article","rect":[35.76740646362305,713.0361328125,71.2615318411391,707.90185546875]},{"page":1,"text":"distributed","rect":[35.98330307006836,725.0,70.20878442442336,719.8152465820313]},{"page":1,"text":"conditions of the Creative Commons","rect":[35.98330307006836,736.9176025390625,153.01913424479182,731.7136840820313]},{"page":1,"text":"Attribution (CC BY) license (https://","rect":[35.711429595947269,750.6482543945313,154.2877316388978,743.6400146484375]},{"page":1,"text":"creativecommons.org/licenses/by/","rect":[35.98330307006836,762.5755615234375,146.39010285471813,755.5534057617188]},{"page":1,"text":"4.0/).","rect":[35.98330307006836,774.0142822265625,52.984516412507158,767.4658203125]},{"page":1,"text":"2","rect":[167.18743896484376,249.73057556152345,170.17485329546265,245.6044158935547]},{"page":1,"text":"3","rect":[167.18743896484376,271.328369140625,170.17485329546265,267.1006774902344]},{"page":1,"text":"*","rect":[166.47776794433595,292.9587707519531,170.01485183963934,290.0686950683594]},{"page":1,"text":"Abstract: In the present work, the dielectric properties of recycled liquid crystals (LCs) (non-purified,","rect":[166.8376007080078,323.8237609863281,560.1409398199091,314.77728271484377]},{"page":1,"text":"purified, and doped with diamond nanoparticles at 0.05, 0.1, and 0.2 wt%) were investigated. The","rect":[166.91856384277345,336.78204345703127,559.0192742768937,327.7355651855469]},{"page":1,"text":"studied LC mixtures were obtained from industrial recycling of end-of-life LC displays presenting","rect":[167.18743896484376,349.7393493652344,559.0155027023285,340.69287109375]},{"page":1,"text":"mainlynematicphases. Dielectricmeasurementswerecarriedoutatroomtemperatureonafrequency","rect":[167.18743896484376,362.6966552734375,559.3656464485404,353.6501770019531]},{"page":1,"text":"range from 0.1 to 106 Hz using an impedance analyzer. The amplitude of the oscillating voltage","rect":[167.18743896484376,375.6549072265625,559.0178714181571,365.07763671875]},{"page":1,"text":"was fixed at 1 V using cells with homogeneous and homeotropic alignments. Results show that the","rect":[166.8106231689453,388.6122131347656,559.0193951780797,379.56573486328127]},{"page":1,"text":"dielectric anisotropy of all purified samples presents positive values and decreases after the addition","rect":[167.18743896484376,401.5705261230469,559.0174561465283,392.5240478515625]},{"page":1,"text":"of diamond nanoparticles to the LC mixtures. DC conductivity values were obtained by applying the","rect":[167.18743896484376,414.52777099609377,559.0143678433833,405.4812927246094]},{"page":1,"text":"universal law of dielectric response proposed by Jonscher. In addition, conductivity of the doped LC","rect":[167.18743896484376,427.4850769042969,559.0175765589393,418.4385986328125]},{"page":1,"text":"mixtures is lower than that of the undoped and non-purified LC.","rect":[167.18743896484376,440.4254455566406,423.2655544061405,431.3968811035156]},{"page":1,"text":"Keywords: nematic liquid crystals; recycling; dielectric properties; diamond nanoparticles; Jonscher","rect":[167.18743896484376,465.343017578125,559.0967257310883,456.314453125]},{"page":1,"text":"1. Introduction","rect":[167.18743896484376,513.0234985351563,235.270163014805,505.6987609863281]},{"page":1,"text":"At present, liquid crystals (LCs) represent a very important value in display systems.","rect":[188.43658447265626,531.1962280273438,560.7562447610197,521.16455078125]},{"page":1,"text":"LCs exhibit an organized structure between solid and isotropic liquid states. These ma-","rect":[167.18743896484376,543.7360229492188,560.6649205696111,533.704345703125]},{"page":1,"text":"terials behave physically like a liquid, but at the same time, exhibit the properties of an","rect":[167.18743896484376,556.2756958007813,559.0194269793133,546.22412109375]},{"page":1,"text":"organized medium. In general, depending on position, chirality, and order of orientation of","rect":[167.18743896484376,568.8153686523438,559.0139087554379,558.7637939453125]},{"page":1,"text":"the LC molecules, three major mesophases are found: nematic, smectic, and cholesteric [1,2].","rect":[167.18743896484376,581.3551635742188,560.7589192455897,571.3035888671875]},{"page":1,"text":"Mesogens can have various structures; they can be calamitic, discotic, banana shaped, or","rect":[167.18743896484376,593.8948364257813,559.2110787327787,583.8631591796875]},{"page":1,"text":"LC polymers. The recycled LCs studied in this report mainly present a nematic phase and","rect":[167.18743896484376,606.4345703125,559.0107490779127,596.4028930664063]},{"page":1,"text":"their molecules exhibit an elongated shape, represented by rods distributed in an ordered","rect":[167.18743896484376,618.9743041992188,559.0200525739593,608.942626953125]},{"page":1,"text":"way. In this phase, the long axes of the molecules are arranged approximately in the same","rect":[166.7686309814453,631.5140380859375,559.015850728064,621.4624633789063]},{"page":1,"text":"direction, but their positions are freely distributed. This means that they have only one","rect":[167.18743896484376,644.0537719726563,559.0194451181025,634.002197265625]},{"page":1,"text":"order of orientation, and no privileged position in space. This preferential direction is","rect":[167.18743896484376,656.593505859375,559.0193961390047,646.5419311523438]},{"page":1,"text":"→","rect":[522.3906860351563,661.5437622070313,530.2766279250922,657.4376220703125]},{"page":1,"text":"referred to as the director of the nematic LC, often represented by a vector noted n [3].","rect":[167.18743896484376,671.0841674804688,546.9568413725899,661.0325927734375]},{"page":1,"text":"The orientational order is one of the most important features of LCs, providing an","rect":[188.43658447265626,683.6239013671875,559.0199152605633,673.5723266601563]},{"page":1,"text":"anisotropic character, i.e., LCs give different responses depending on the direction in which","rect":[167.18743896484376,696.1636352539063,559.0138626365452,686.112060546875]},{"page":1,"text":"the external field (electric, magnetic) is applied [1,2]. Thus, in a nematic LC, ε// represents","rect":[167.18743896484376,708.8372802734375,559.011400783783,698.6517944335938]},{"page":1,"text":"→","rect":[433.0391540527344,713.8074340820313,440.9250959426703,709.7012939453125]},{"page":1,"text":"the dielectric permittivity when the electric field is parallel to n, and ε⊥ corresponds to the","rect":[167.18743896484376,723.3468627929688,559.0185917159561,713.2952880859375]},{"page":1,"text":"→","rect":[372.6431579589844,728.298095703125,380.5290998489203,724.1919555664063]},{"page":1,"text":"case when the electric field is perpendicular to n [4]. Magnitude and sign of the dielectric","rect":[167.18743896484376,737.8385620117188,559.0130329984837,727.7869873046875]},{"page":1,"text":"anisotropy (∆ε) are two of the most influential factors in the selection of nematic LC fora","rect":[167.18743896484376,750.3782348632813,559.0119328374226,740.32666015625]},{"page":1,"text":"particular application [5].","rect":[166.88856506347657,762.8970947265625,278.76647272024618,752.8853149414063]},{"page":1,"text":"Molecules 2021, 26, 2873. https://doi.org/10.3390/molecules26102873","rect":[35.983306884765628,822.007568359375,280.42439521175427,813.9264526367188]},{"page":1,"text":"https://www.mdpi.com/journal/molecules","rect":[400.1435546875,822.007568359375,557.0259491512863,813.9822387695313]},{"page":2,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":2,"text":"2 of 13","rect":[536.0813598632813,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":2,"text":"The remarkable point of the approach presented here, unique in Europe, is the attempt","rect":[188.43658447265626,106.34895324707031,559.018167805624,96.31727600097656]},{"page":2,"text":"to revalorize LCs present in end-of-life LCDs. Nowadays, LCs represent an important","rect":[167.18743896484376,118.90767669677735,559.0194797655953,108.85609436035156]},{"page":2,"text":"economic value of the recycling system of LCDs. The reuse of these organic molecules","rect":[167.18743896484376,131.44735717773438,559.0193961390047,121.39576721191406]},{"page":2,"text":"could become a profitable basis since it permits to preserve the value of these materials. On","rect":[167.18743896484376,143.96717834472657,559.0138626365452,133.9355010986328]},{"page":2,"text":"a global level, the only pilot plant known for “total waste-free processing” of end-of-life","rect":[167.18743896484376,156.52676391601563,559.0114918229178,146.4751739501953]},{"page":2,"text":"LCDs is located in Taiwan, established by researchers of the Industrial Technology Research","rect":[167.18743896484376,169.06649780273438,559.0138626365452,159.01490783691407]},{"page":2,"text":"Institute (ITRI). After more than a decade of research, they developed a recycling process","rect":[167.18743896484376,181.60629272460938,559.0110345734781,171.55470275878907]},{"page":2,"text":"to obtain LCs with less than 1 ppb of impurities [6]. At this purity level, LCs can be easily","rect":[167.18743896484376,194.14602661132813,559.4019679383516,184.0944366455078]},{"page":2,"text":"reused to manufacture new LCDs or smart windows.","rect":[167.18743896484376,204.06829833984376,400.9907769194649,196.6341094970703]},{"page":2,"text":"The presence of ionic impurities in LC mixtures causes a large number of undesirable","rect":[188.43658447265626,219.22543334960938,559.011331329432,209.17384338378907]},{"page":2,"text":"effects; for example, they tend to increase the electrical conductivity, which can lead to","rect":[167.18743896484376,231.76522827148438,559.0193094710487,221.71363830566407]},{"page":2,"text":"alterations in optical and electro-optical properties (sticking and flickering images, slow","rect":[167.18743896484376,244.30496215820313,559.4369319705179,234.2533721923828]},{"page":2,"text":"response in electro-optical devices) [7]. Therefore, it is essential that the recovered LC","rect":[167.18743896484376,256.8247375488281,559.0172695686902,246.7930450439453]},{"page":2,"text":"mixtures possess high purity so that the recycled LCs could regain new life.","rect":[167.18743896484376,269.3843688964844,499.17647638235555,259.332763671875]},{"page":2,"text":"To achieve purification of LCs, several physicochemical methods exist which are often","rect":[188.43658447265626,281.9240417480469,559.0180130271702,271.8724365234375]},{"page":2,"text":"expensive, difficult, and/or time consuming [8]. Once purified, even using a sophisticated","rect":[167.18743896484376,294.4637756347656,559.0174178991514,284.41217041015627]},{"page":2,"text":"purification method that would result in highly purified LCs, ionic contamination can still","rect":[166.88856506347657,307.0035705566406,559.0162555768699,296.95196533203127]},{"page":2,"text":"occur, for example, during the manufacture of new LC-based devices [7–9]. Based on this","rect":[167.18743896484376,319.5433044433594,559.0170556304113,309.49169921875]},{"page":2,"text":"observation, establishment of a persistent purification method is mandatory.","rect":[167.18743896484376,332.0830078125,502.44274225149618,322.0314025878906]},{"page":2,"text":"During the last 20 years, one of the most promising and studied ways to capture ionic","rect":[188.43658447265626,344.6227111816406,559.0169570041715,334.57110595703127]},{"page":2,"text":"impurities consists to add inorganic or organic nanomaterials as ion-adsorbent materials","rect":[167.18743896484376,357.1624755859375,559.0136007824663,347.13079833984377]},{"page":2,"text":"to LCs. In general, adding a small amount of nanomaterials (concentrations lower than","rect":[167.18743896484376,369.70220947265627,559.0194269793133,359.6506042480469]},{"page":2,"text":"1 wt%) will be sufficient to significantly improve electro-optical, magnetic, and dielectric","rect":[166.68966674804688,382.2419738769531,559.0149953949026,372.19036865234377]},{"page":2,"text":"properties of LCs [10]. The most commonly investigated dopants were noble metals [11],","rect":[166.88856506347657,394.78167724609377,560.2613383989105,384.7300720214844]},{"page":2,"text":"ferroelectrics [12], semiconductors, magnetics or insulators nanoparticles [13–15], carbon-","rect":[167.18743896484376,407.3214111328125,560.66848498945,397.2698059082031]},{"page":2,"text":"based nanomaterials (fullerenes, graphenes, carbon nanotubes [16]), carbon dots [8,9], and","rect":[167.18743896484376,419.86114501953127,559.0168685827451,409.8095397949219]},{"page":2,"text":"diamond nanoparticles (DNPs) [17–20]. After addition of such nanoparticles to LCs, two","rect":[167.18743896484376,432.3809509277344,559.0165077108823,422.3492431640625]},{"page":2,"text":"main effects have been reported: either the electrical conductivity increases or decreases.","rect":[167.18743896484376,444.94061279296877,555.7579277983712,434.8890075683594]},{"page":2,"text":"Inthisreport, dielectricproperties(ε’, ε”, ∆ε)ofnon-purified, purified, andnanoparticle-","rect":[188.43658447265626,457.45941162109377,566.8485645171567,447.4277038574219]},{"page":2,"text":"doped recycled LCs mixtures are investigated. A particular interest is given to DNPs to","rect":[167.18743896484376,470.0190734863281,559.0194315413612,459.9873962402344]},{"page":2,"text":"study their impact on mobile ions present in the recovered LCs. DNPs belong to one of three","rect":[167.18743896484376,482.55877685546877,559.0138309737686,472.5071716308594]},{"page":2,"text":"allotropic forms of carbon [21]. They are interesting materials for their mechanical, thermal,","rect":[167.18743896484376,495.0985107421875,560.2568440502772,485.0469055175781]},{"page":2,"text":"and optical characteristics. Moreover, they are chemically stable and non-conductive,","rect":[167.18743896484376,507.63824462890627,560.2585234135124,497.6065673828125]},{"page":2,"text":"non-toxic and possess high surface areas, inert surface, and tunable surface structures [22].","rect":[167.18743896484376,520.1779174804688,560.718275288531,510.1263427734375]},{"page":2,"text":"2. Results and Discussion","rect":[167.18743896484376,539.9230346679688,283.9148926290628,532.5983276367188]},{"page":2,"text":"The complex dielectric permittivity (ε*) is given by Equation (1) [4]:","rect":[188.43658447265626,558.0958251953125,484.7284173003243,548.0641479492188]},{"page":2,"text":"ε*(ω) = ε’(ω) − iε”(ω),","rect":[312.5830383300781,580.4088134765625,413.6193169585274,571.0538330078125]},{"page":2,"text":"where ω stands for the angular frequency (ω = 2πf), f is the frequency of the measuring elec-","rect":[166.7686309814453,604.0751342773438,560.6669238921567,594.0235595703125]},{"page":2,"text":"tric field, i = √−1, and ε’ and ε” represent the real and imaginary parts of ε*, respectively.","rect":[167.18743896484376,616.6149291992188,560.7625184086016,605.1234130859375]},{"page":2,"text":"The dielectric anisotropy is obtained by Equation (2):","rect":[166.8785858154297,629.1536254882813,399.60653009329305,619.1219482421875]},{"page":2,"text":"∆ε = ε’// − ε’⊥.","rect":[328.0597839355469,652.2781982421875,398.2678765288399,642.2808227539063]},{"page":2,"text":"2.1. Dielectric Measurements: Effect of the Amplitude of the Oscillating Voltage","rect":[167.18739318847657,674.4659423828125,488.79028047848427,664.4342651367188]},{"page":2,"text":"The quality of the linear dielectric response depends on the studied material, on the","rect":[188.43658447265626,690.0611572265625,559.0174006418439,680.0095825195313]},{"page":2,"text":"device characterization, and also on the amplitude of the sinusoidal voltage to be applied","rect":[167.18743896484376,702.6008911132813,559.0200144242162,692.54931640625]},{"page":2,"text":"(Ve). Preliminary measurements were carried out at room temperature for Ve = 0.1 and","rect":[166.85858154296876,715.140625,559.0136300507495,705.0890502929688]},{"page":2,"text":"1 V. Figure 1 presents the spectra ε’ and ε” as a function of frequency of a non-purified LC","rect":[166.68966674804688,727.6803588867188,559.0196953216109,717.6287841796875]},{"page":2,"text":"mixture in homogeneous (HG cell) and homeotropic (HT cell) alignments.","rect":[167.18743896484376,740.2200927734375,492.65404596243368,730.1884155273438]},{"page":3,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":3,"text":"HT cell","rect":[138.1982879638672,120.6851806640625,165.00035666605914,114.2956771850586]},{"page":3,"text":"HG cell","rect":[372.230712890625,120.6851806640625,400.3054714121529,114.2956771850586]},{"page":3,"text":"3 of 13","rect":[536.0813598632813,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":3,"text":"(a)","rect":[176.22666931152345,263.67724609375,185.72198196345387,255.75628662109376]},{"page":3,"text":"(b)","rect":[396.85235595703127,263.1678466796875,406.8064393609148,255.05972290039063]},{"page":3,"text":"Figure 1. Dielectric spectra of a non-purified LC mixture at room temperature (20 ◦C), using 20 µm cells in (a) homeotropic","rect":[57.23345184326172,283.5863952636719,537.7666657165697,274.5399169921875]},{"page":3,"text":"and (b) homogeneous alignment, for two amplitudes of the oscillating voltage: 0.1 and 1 V.","rect":[57.23345184326172,296.3938903808594,416.54762838074989,287.347412109375]},{"page":3,"text":"The spectra observed for Ve = 0.1 V show a significant sensitivity of the dielectric","rect":[188.43658447265626,319.0288391113281,559.0206346527107,308.97723388671877]},{"page":3,"text":"signal to external electromagnetic disturbances. When Ve = 1 V, this phenomenon appears","rect":[167.18743896484376,331.5685729980469,559.0165601237236,321.5368957519531]},{"page":3,"text":"much weaker, although the permittivities are quite close to those obtained for Ve = 0.1 V.","rect":[167.18743896484376,344.1083068847656,560.7597603293624,334.05670166015627]},{"page":3,"text":"The difference between the two sets of measurements can be quantitatively assessed by the","rect":[166.8785858154297,356.6470031738281,559.0173710128311,346.59539794921877]},{"page":3,"text":"parameter δ (distortion measure), given by Equation (3):","rect":[166.88856506347657,369.186767578125,414.09533014212118,359.15509033203127]},{"page":3,"text":"δ(ε) = 1m00·max∑(l|ologg(ε(1εV1V(f()f))))−−mloign((εlo0.g1V(ε(1fV))(|f)))","rect":[250.13296508789063,404.68121337890627,467.27032331636357,380.6373596191406]},{"page":3,"text":",","rect":[473.58026123046877,396.0,476.0697564116524,389.0]},{"page":3,"text":"(3)","rect":[547.40869140625,397.17767333984377,559.0197429328991,387.82275390625]},{"page":3,"text":"where m stands for the number of measurement frequencies. δ represents a mean absolute","rect":[166.7686309814453,426.11358642578127,559.0138948059945,416.0818786621094]},{"page":3,"text":"difference, expressed as a percentage of the maximum range of the 1V spectra. The δ","rect":[167.18743896484376,438.6722412109375,559.0159869173108,428.6206359863281]},{"page":3,"text":"data were found between 3% and 8.5% (δ(ε’⊥) = 8.5%; δ(ε”⊥) = 4.6%; δ(ε’//) = 3.2%; and","rect":[167.18743896484376,451.3468322753906,559.0208888801435,441.16033935546877]},{"page":3,"text":"δ(ε”//) = 3.4%). Consequently, a value of 1 V for the sinusoidal voltage of the electric field","rect":[167.18743896484376,463.88653564453127,559.0135149160349,453.7001037597656]},{"page":3,"text":"measurement has been chosen for all measurements presented in this work.","rect":[167.18743896484376,476.2715148925781,499.79390802298055,466.23980712890627]},{"page":3,"text":"2.2. Effect of Alignment on Dielectric Properties of Non-Purified LCs Mixtures","rect":[167.18743896484376,498.61407470703127,485.275326865203,488.5823974609375]},{"page":3,"text":"Figure 2 shows the real part of the complex permittivity in homogeneous and","rect":[188.43658447265626,514.2092895507813,559.019855636687,504.1576843261719]},{"page":3,"text":"homeotropic alignments of three non-purified LC mixtures (NP-M1, NP-M2, and NP-","rect":[167.18743896484376,526.7490234375,560.6649205696111,516.6974487304688]},{"page":3,"text":"M3). A fundamental point for the reuse of a recycled product is the reproducibility of","rect":[167.18743896484376,539.2887573242188,559.0194737922674,529.2371826171875]},{"page":3,"text":"its properties. The characteristics of the different mixtures must be almost identical to","rect":[167.18743896484376,551.8085327148438,559.0194315413612,541.77685546875]},{"page":3,"text":"consider a future reuse. It is therefore necessary to measure their characteristics and mainly","rect":[167.18743896484376,564.3681640625,559.4041762459415,554.3165893554688]},{"page":3,"text":"their permittivities.","rect":[167.18743896484376,576.8880004882813,252.23854913626179,566.876220703125]},{"page":3,"text":"(a)","rect":[192.16293334960938,743.9586791992188,202.36657256373005,735.57177734375]},{"page":3,"text":"(b)","rect":[400.88421630859377,744.3901977539063,411.571894829355,735.8051147460938]},{"page":3,"text":"Figure 2. (a) Relative permittivity and (b) dielectric anisotropy of three non-purified LC mixtures as function of frequency.","rect":[57.23345184326172,764.1159057617188,539.3384353947845,755.0693969726563]},{"page":3,"text":"Measurements were taken at 1 V and room temperature (20 ◦C) with 20 µm cells in homogeneous and homeotropic","rect":[57.23345184326172,776.9243774414063,537.7698187854613,767.895751953125]},{"page":3,"text":"alignments. NP-M stands for non-purified LCs mixtures.","rect":[57.23345184326172,789.7327880859375,282.1857204217655,780.686279296875]},{"page":4,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":4,"text":"4 of 13","rect":[536.0813598632813,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":4,"text":"In Figure 2a, two distinct frequency regions can be appreciated:","rect":[188.43658447265626,108.14791107177735,466.9313286772774,98.09632873535156]},{"page":4,"text":"The first one is situated between 0.1 and 10 Hz. When frequency decreases, a sig-","rect":[188.43658447265626,120.68770599365235,560.6653478157049,110.63612365722656]},{"page":4,"text":"nificant increase of the values of ε’// and ε’⊥ is observed, to reach values higher than","rect":[167.18743896484376,133.36228942871095,559.013018287907,123.17585754394531]},{"page":4,"text":"103. This phenomenon can be attributed to the space charge polarization that is normally","rect":[166.68966674804688,145.76718139648438,559.4086635545067,134.13621520996095]},{"page":4,"text":"created at the interfaces formed between the electrodes of the cell and the LCs known as","rect":[167.18743896484376,155.68951416015626,559.0166453154737,148.2553253173828]},{"page":4,"text":"electrode polarization, and to a contribution of the electrical conductivity produced by the","rect":[167.18743896484376,170.84664916992188,559.017575071966,160.79505920410157]},{"page":4,"text":"ionic impurities present especially in the non-purified (NP) samples. Interestingly, in this","rect":[167.18743896484376,183.38644409179688,559.0109735383219,173.33485412597657]},{"page":4,"text":"frequency range, all ε’// as well as ε’⊥ curves of NP-M1-3 are superimposed, exhibiting","rect":[167.18743896484376,196.0599822998047,559.016571794308,185.87452697753907]},{"page":4,"text":"an overall shift between ε’// and ε’⊥. All NP-LCs mixtures possess a negative dielectric","rect":[167.18743896484376,208.5996551513672,559.0174608245857,198.41322326660157]},{"page":4,"text":"anisotropy because the curve of ε’⊥ has larger values than ε’// as illustrated in Figure 2b.","rect":[167.18743896484376,221.1394500732422,559.2554863921212,210.95301818847657]},{"page":4,"text":"The second one is situated between 10 and 106 Hz. For each LC mixture, permittivity","rect":[188.43658447265626,233.54428100585938,559.4053078777349,221.91429138183595]},{"page":4,"text":"is independent of frequency. At such frequencies, the ionic impurities cannot follow the","rect":[167.18743896484376,246.08407592773438,559.01932304779,236.03248596191407]},{"page":4,"text":"periodic inversion of the electric field. Contrary to the phenomenon observed between 0.1","rect":[166.88856506347657,258.6237487792969,559.5123745233427,248.57215881347657]},{"page":4,"text":"and 10 Hz, the dielectric anisotropy remains positive (ε’// > ε’⊥). The inset of Figure 2b","rect":[167.18743896484376,271.29833984375,559.016190704752,261.1119384765625]},{"page":4,"text":"presents an extended view of ∆ε in the frequency range between 30 and 105 Hz in order to","rect":[166.88856506347657,283.7032165527344,559.0144419516882,272.0732421875]},{"page":4,"text":"visualize the different dielectric anisotropy values. There are found as: 1.87, 1.99, and 0.90","rect":[166.9085693359375,296.2430114746094,559.0172316854139,286.19140625]},{"page":4,"text":"for NP-M1; NP-M2; and NP-M3, respectively.","rect":[167.18743896484376,308.7826843261719,366.9445122710274,298.7310791015625]},{"page":4,"text":"It was expected to obtain identical phenomena in both frequency domains. However,","rect":[188.43658447265626,321.3223571777344,560.2654035702651,311.270751953125]},{"page":4,"text":"a clear difference of the results between these two frequency ranges and especially a sign","rect":[167.18743896484376,333.8621520996094,559.0116563223859,323.810546875]},{"page":4,"text":"inversion of ∆ε is observed for the three LC mixtures.","rect":[167.18743896484376,343.78448486328127,402.3080376616524,336.35028076171877]},{"page":4,"text":"In terms of optical appearance, the extracted LCs present a black coloration that is not","rect":[188.43658447265626,358.9217224121094,559.011476550763,348.8900146484375]},{"page":4,"text":"typical for nematic LCs (see Figure 6c in Section 3.2). It is obvious that during the industrial","rect":[167.18743896484376,371.4813537597656,559.0138282909289,361.42974853515627]},{"page":4,"text":"recovering procedure applied to extract the LCs, several sources of contamination appeared.","rect":[167.18743896484376,384.0210266113281,560.7606282299647,373.96942138671877]},{"page":4,"text":"For example, the organic solvent used can capture unwanted molecules by solubilizing","rect":[167.18743896484376,396.5607604980469,559.0194404466517,386.5290832519531]},{"page":4,"text":"a significant number of organic and inorganic impurities. In addition, impurities such","rect":[167.18743896484376,409.1004943847656,559.019365944157,399.04888916015627]},{"page":4,"text":"as dust, water, adhesive residues, scraps, and other materials, present in a storage and","rect":[167.18743896484376,421.6402587890625,559.0194283905933,411.60858154296877]},{"page":4,"text":"treatment plant of Waste Electrical and Electronic Equipment (WEEE), could be added to","rect":[167.18743896484376,434.16009521484377,559.020949642007,424.1283874511719]},{"page":4,"text":"the solution containing the extracted LCs.","rect":[167.18743896484376,446.7197265625,350.4441460600899,436.68804931640627]},{"page":4,"text":"For all reasons mentioned above, purification of these mixtures is a mandatory step","rect":[188.43658447265626,459.25946044921877,559.3138322399905,449.2078552246094]},{"page":4,"text":"for the possible reuse of the LCs.","rect":[167.18743896484376,471.7792663574219,310.50267877493368,461.74755859375]},{"page":4,"text":"2.3. Dielectric Anisotropy of Purified LC Mixtures and Doped with DNPs","rect":[167.18743896484376,494.121826171875,465.7177401952811,484.09014892578127]},{"page":4,"text":"After purification, all LC mixtures exhibit quite comparable properties, the same","rect":[188.43658447265626,509.6961364746094,559.0198723641962,499.6644287109375]},{"page":4,"text":"optical appearance and equivalent dielectric anisotropy values at 1 kHz (see Figure S1","rect":[167.18743896484376,522.2557983398438,559.5171688973375,512.22412109375]},{"page":4,"text":"in Supplementary Materials). Therefore, the results of doping for only one of these LC","rect":[167.18743896484376,534.7954711914063,559.0194057991589,524.743896484375]},{"page":4,"text":"mixtures will be presented in the following sections in order to avoid redundancy. The","rect":[167.18743896484376,547.335205078125,559.0194451181025,537.2836303710938]},{"page":4,"text":"dielectric properties of such a representative purified LC mixture doped with three different","rect":[167.18743896484376,559.8550415039063,559.0138953446865,549.8233642578125]},{"page":4,"text":"concentrations of DNPs (0.05, 0.1, and 0.2 wt%) were measured. Figure 3 illustrates the","rect":[167.18743896484376,572.4146118164063,559.0194451181025,562.363037109375]},{"page":4,"text":"real (dielectric constant ε’) and imaginary (dielectric loss ε”) parts of the complex dielectric","rect":[167.18743896484376,584.9544067382813,559.0165105020423,574.90283203125]},{"page":4,"text":"permittivity, and the dielectric anisotropy.","rect":[166.88856506347657,597.4940795898438,350.99169244680868,587.46240234375]},{"page":4,"text":"Figure 3a,c show two different regions of the real part of the dielectric permittivity for","rect":[188.43658447265626,610.0338745117188,559.2168490289871,599.9822998046875]},{"page":4,"text":"homeotropic and homogeneous alignments. At low frequencies between 0.1 and 10 Hz,","rect":[167.18743896484376,622.5736083984375,560.2605986088249,612.5220336914063]},{"page":4,"text":"when frequency decreases, a significant increase of ε’ is observed for the purified LC","rect":[166.7686309814453,635.1133422851563,559.0166592171277,625.061767578125]},{"page":4,"text":"mixture. As explained earlier, this phenomenon is a combination of electrode polarization","rect":[167.18743896484376,647.6331176757813,559.020173476421,637.6014404296875]},{"page":4,"text":"and electrical conductivity produced from ionic impurities still present in the purified LC","rect":[167.18743896484376,660.1927490234375,559.0155704938144,650.1411743164063]},{"page":4,"text":"sample. On the other hand, doped samples do not reveal a significant increase of ε’ with","rect":[167.18743896484376,672.7324829101563,559.0144474785334,662.680908203125]},{"page":4,"text":"decreasing frequency. For samples doped with DNPs, a strong flattening of the slopes of","rect":[167.18743896484376,685.272216796875,559.019862131226,675.2206420898438]},{"page":4,"text":"the ε’ curves is observed compared to the purified LC sample. At frequencies between 10","rect":[167.18743896484376,697.7920532226563,559.016440297876,687.7603759765625]},{"page":4,"text":"and 105 Hz, ε’ remains almost constant for all samples since at such frequencies, the ions","rect":[167.18743896484376,710.331787109375,559.0200705090288,698.7207641601563]},{"page":4,"text":"as impurities can no longer follow the periodic inversion of the electric field [23]. It should","rect":[167.18743896484376,722.8914184570313,559.0192645806075,712.83984375]},{"page":4,"text":"be noted that above 105 Hz, ε’decreases for all samples with increasing frequency, for the","rect":[167.18743896484376,735.43115234375,559.0139980326209,723.8002319335938]},{"page":4,"text":"homeotropic alignment.","rect":[167.18743896484376,747.9708862304688,272.85155572805868,737.939208984375]},{"page":5,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":5,"text":"HT cell","rect":[145.84133911132813,127.63024139404297,177.81035723353558,120.11317443847656]},{"page":5,"text":"(a) ","rect":[175.28768920898438,283.0298156738281,189.42612543344647,273.7110595703125]},{"page":5,"text":"HG cell","rect":[147.7004852294922,327.57861328125,181.1667872872465,320.0615234375]},{"page":5,"text":"(c)","rect":[181.2245635986328,477.0441589355469,192.3576347829171,467.72540283203127]},{"page":5,"text":"HT cell","rect":[390.58782958984377,128.3494110107422,422.55683245326216,120.83235168457031]},{"page":5,"text":"(b)","rect":[413.6769104003906,283.0298156738281,425.8856194020577,273.4908447265625]},{"page":5,"text":"HG cell","rect":[394.5460205078125,327.57861328125,428.01230730677778,320.0615234375]},{"page":5,"text":"(d)","rect":[417.0951843261719,478.5425720214844,429.9068291188546,469.00360107421877]},{"page":5,"text":"5 of 13","rect":[536.0813598632813,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":5,"text":"(e)","rect":[300.2097473144531,682.5070190429688,311.701354265339,673.188232421875]},{"page":5,"text":"Figure 3. Dielectric permittivity of purified LCs doped with different concentrations of DNPs (0.05, 0.1, and 0.2 wt%): (a)","rect":[57.23345184326172,707.986328125,538.662824312619,698.9398193359375]},{"page":5,"text":"real and (b) imaginary parts in homeotropic alignment, (c) real and (d) imaginary parts in homogeneous alignment, and","rect":[57.23345184326172,720.7937622070313,537.7702434309019,711.76513671875]},{"page":5,"text":"(e) dielectric anisotropy. The spectra were measured under identical experimental conditions (P stands for purified LC","rect":[56.937591552734378,733.6021728515625,537.7635408811178,724.5556640625]},{"page":5,"text":"mixtures; P + 0.05D, P + 0.1D, and P + 0.2D correspond to purified LC mixtures doped with 0.05, 0.1, and 0.2 wt% of DNPs,","rect":[57.23345184326172,746.3927001953125,538.884389143333,737.3641357421875]},{"page":5,"text":"respectively).","rect":[57.23345184326172,759.2191162109375,110.06586263367957,750.1904907226563]},{"page":6,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":6,"text":"6 of 13","rect":[536.0813598632813,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":6,"text":"Figure 3b,d also present two different regions of the imaginary part of the dielectric","rect":[188.43658447265626,108.14791107177735,559.018615988533,98.09632873535156]},{"page":6,"text":"permittivity: at high frequencies, a relaxation mechanism appears in the imaginary part","rect":[166.88856506347657,120.68770599365235,559.0150852343453,110.63612365722656]},{"page":6,"text":"of ε*. Nevertheless, this relaxation phenomenon seems not to be associated to any LCs","rect":[167.18743896484376,133.22744750976563,559.0179312952547,123.17585754394531]},{"page":6,"text":"molecules. It might correspond to the relaxation of the measuring cell due to the resistance","rect":[167.18743896484376,145.76718139648438,559.0191682672572,135.71559143066407]},{"page":6,"text":"of the ITO layer [24], in relationship with parasitic impedances caused by connectors, cables,","rect":[167.18743896484376,158.30691528320313,560.2605061596522,148.2553253173828]},{"page":6,"text":"etc., which become important at frequencies above 100 kHz [4]. The dielectric response of","rect":[167.18743896484376,170.8267364501953,559.0145555638483,160.79505920410157]},{"page":6,"text":"the analyzed LCs is hidden by the response of the measuring cells. This effect has already","rect":[167.18743896484376,183.38644409179688,559.4072342545971,173.33485412597657]},{"page":6,"text":"been discussed by other authors [25–28].","rect":[167.18743896484376,195.92611694335938,345.2660149565743,185.89442443847657]},{"page":6,"text":"The addition of DNPs to LC mixtures decreases ε’and ε” by more than two orders of","rect":[188.43658447265626,208.46481323242188,559.0113000085387,198.41322326660157]},{"page":6,"text":"magnitude at low frequencies, compared to the purified sample.","rect":[167.18743896484376,221.00460815429688,449.4164360991524,210.95301818847657]},{"page":6,"text":"A comparison between ∆ε data from Figure 2b with the corresponding result for the","rect":[188.43658447265626,233.54428100585938,559.015618462807,223.49269104003907]},{"page":6,"text":"purified LC mixture in Figure 3e reveals an increase of the dielectric anisotropy of the latter,","rect":[166.88856506347657,246.08407592773438,560.2568440502772,236.03248596191407]},{"page":6,"text":"due to the important reduction of the amount of impurities. In the case of the NP samples,","rect":[167.18743896484376,258.6038513183594,560.2615972759568,248.57215881347657]},{"page":6,"text":"the orientational effects are perturbed due to the presence of impurities.","rect":[167.18743896484376,271.1436462402344,482.5565728179024,261.1119384765625]},{"page":6,"text":"According to the data presented in Figure 3e, the dielectric anisotropy of the purified","rect":[188.43658447265626,283.7032165527344,559.0164482328571,273.651611328125]},{"page":6,"text":"sample decreases by roughly 30% by adding DNPs. ∆ε presents positive values for all","rect":[167.18743896484376,296.2430114746094,559.0184720345785,286.19140625]},{"page":6,"text":"samples in the whole frequency range, since the longitudinal component of the dielectric","rect":[167.18743896484376,308.7826843261719,559.0116264495924,298.7310791015625]},{"page":6,"text":"constant is always greater than the perpendicular one (Figure 3a,c). A small dependence","rect":[167.18743896484376,321.3223571777344,559.0153348089674,311.2906799316406]},{"page":6,"text":"between the amount of DNPs present in the LC mixtures and the decrease of the dielectric","rect":[167.18743896484376,333.8422546386719,559.0176061311811,323.810546875]},{"page":6,"text":"anisotropy is also observed, such that the larger the amount of nanoparticles, the lower the","rect":[167.18743896484376,346.4018859863281,559.0132294163666,336.35028076171877]},{"page":6,"text":"dielectric anisotropy. However, the y-axis scale of this figure does not allow to appreciate","rect":[167.18743896484376,358.9416198730469,559.0194636776507,348.8900146484375]},{"page":6,"text":"this behavior. Therefore, an inset applying a different scaling has been added to better","rect":[167.18743896484376,371.4813537597656,559.2123878917872,361.42974853515627]},{"page":6,"text":"illustrate the evolution of ∆ε. More precisely, the following ∆ε data (at 1 kHz) are found:","rect":[167.18743896484376,384.0210266113281,560.2561116383913,373.96942138671877]},{"page":6,"text":"3.36; 2.38; 2.25; and 2.17 for P; P + 0.05D; P + 0.1D; and P + 0.2D wt% LCs mixtures,","rect":[167.18743896484376,395.2669982910156,560.2586454838249,386.5091552734375]},{"page":6,"text":"respectively. These values are within the range of dielectric anisotropy values of LCs","rect":[167.18743896484376,409.1004943847656,559.0193961390047,399.04888916015627]},{"page":6,"text":"mixtures developed by Merck [29,30]. The decrease of ∆ε may be related to the dipole–","rect":[167.18743896484376,421.6402587890625,560.5137509285875,411.5886535644531]},{"page":6,"text":"dipole interactions between the nematic LC molecules and the DNPs, and has already been","rect":[167.18743896484376,434.17999267578127,559.0138626365452,424.1483154296875]},{"page":6,"text":"reported by other authors [19,20]. According to the literature, DNPs not only possess a","rect":[167.18743896484376,446.7197265625,559.013140577025,436.68804931640627]},{"page":6,"text":"distinct value of the polarizability α (α = 1.95 × 10−40 C2·m2·J−1) [31] but also a small","rect":[167.18743896484376,459.25946044921877,559.0170071908285,447.5906066894531]},{"page":6,"text":"permanent dipole moment, compared to that of LC molecules. By taking into account","rect":[166.88856506347657,471.7991638183594,559.0150852343453,461.74755859375]},{"page":6,"text":"the volumetric density (ρ = 3.5× 103 kg·m−3) and its polarization (P = 10−7 C·m−2), the","rect":[167.18743896484376,484.3388977050781,559.0160881845087,472.70794677734377]},{"page":6,"text":"permanent dipole moment of diamond can be calculated as: µ = PV = 5.71 × 10−37 C·m (V","rect":[166.88856506347657,496.8587341308594,559.3700376221924,485.2476501464844]},{"page":6,"text":"corresponds to the unit volume). Therefore, ion-dipole interactions are present in LC-DNPs","rect":[167.18743896484376,509.3984375,559.0138999897389,499.3667297363281]},{"page":6,"text":"mixtures, together with dipole–dipole interactions between LC molecules.","rect":[167.18743896484376,521.9580688476563,492.6838921538399,511.9264221191406]},{"page":6,"text":"In summary, the highest value of dielectric anisotropy is obtained by removing all","rect":[188.43658447265626,534.4977416992188,559.019814808016,524.4461669921875]},{"page":6,"text":"impurities present in LCs mixtures. However, the removal process is a rather complex","rect":[167.18743896484376,547.0166625976563,559.2734331458023,537.0048828125]},{"page":6,"text":"task due to various sources and natures of the impurities. Therefore, it is more feasible","rect":[167.18743896484376,559.5563354492188,559.0193840829462,549.524658203125]},{"page":6,"text":"to decrease the amount of impurities by typical purification methods and to decrease the","rect":[167.18743896484376,572.115966796875,559.0193256795358,562.0643920898438]},{"page":6,"text":"electrical conductivity furthermore by adding DNPs.","rect":[167.18743896484376,584.6557006835938,399.36766900930868,574.6041259765625]},{"page":6,"text":"2.4. Frequency Dependence of Real Conductivity for Non-Purified, Purified and Nanoparticle","rect":[167.18743896484376,606.9783935546875,542.2648288183279,596.9467163085938]},{"page":6,"text":"Doped LC Mixtures","rect":[166.79861450195313,617.4283447265625,247.39851106930457,607.3966674804688]},{"page":6,"text":"The complex conductivity (σ*) is an alternative representation of the dielectric proper-","rect":[188.43658447265626,633.0234985351563,560.6652140910193,622.971923828125]},{"page":6,"text":"ties, allowing to better understand or identify the aspects and phenomena of polarization","rect":[167.18743896484376,645.563232421875,559.0200959802247,635.5116577148438]},{"page":6,"text":"and charge transport (ions, impurities). It is represented by Equation (4):","rect":[167.18743896484376,658.1029663085938,485.9920891753243,648.0712890625]},{"page":6,"text":"σ* (ω) = σ’(ω) + iσ”(ω),","rect":[310.7038879394531,680.4159545898438,415.4994439116524,671.0609741210938]},{"page":6,"text":"where σ’ and σ” are the real and imaginary parts of this function. The complex functions","rect":[166.7686309814453,704.081298828125,559.0149221323683,694.0297241210938]},{"page":6,"text":"ε*(ω) and σ*(ω) are related by Equation (5) [4]:","rect":[167.18743896484376,716.6210327148438,373.5735100737618,706.58935546875]},{"page":6,"text":"σ* (ω) = iωε0ε*,","rect":[328.0588073730469,738.9340209960938,398.14440240774618,729.5790405273438]},{"page":7,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":7,"text":"7 of 13","rect":[536.0813598632813,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":7,"text":"where ε0 corresponds to the dielectric permittivity of vacuum (8.85418 × 10−12 F·m−1).","rect":[166.7686309814453,108.14791107177735,560.7592558353874,96.47919464111328]},{"page":7,"text":"Real and imaginary parts of the complex conductivity are given by Equations (6) and (7):","rect":[167.18743896484376,120.68770599365235,557.5203179350899,110.63612365722656]},{"page":7,"text":"σ’(ω) = ωε0ε”(ω),","rect":[323.13409423828127,143.00059509277345,403.06820001516805,133.64564514160157]},{"page":7,"text":"σ”(ω) = ωε0ε’(ω).","rect":[323.13409423828127,165.9893035888672,403.06820001516805,156.6343536376953]},{"page":7,"text":"In this report, the conductivity spectra were analyzed applying Jonscher’s universal","rect":[188.43658447265626,185.47616577148438,559.0123881838152,175.44447326660157]},{"page":7,"text":"power law [32]. This model, known as the Universal Dielectric Response (UDR), is widely","rect":[166.88856506347657,198.01583862304688,559.4066072386376,187.98414611816407]},{"page":7,"text":"used to analyze the frequency dependence of the real part of the complex conductivity. The","rect":[167.18743896484376,210.55563354492188,559.0138920089248,200.50404357910157]},{"page":7,"text":"equation of Jonscher can be expressed as:","rect":[167.18743896484376,223.07545471191407,348.15377130423055,213.0437774658203]},{"page":7,"text":"σ0 = σDC + Aωn.","rect":[324.86932373046877,245.23934936523438,401.33345880423055,234.7622833251953]},{"page":7,"text":"n","rect":[554.1769409179688,260.5248718261719,558.3847986725386,256.8186950683594]},{"page":7,"text":"Equation (8) can also be written in the following form, considering: Aωn =σDC\u0010ffc\u0011","rect":[188.43658447265626,275.42877197265627,553.957731875479,257.53497314453127]},{"page":7,"text":"σ0 = σDC\u00121 + \u0012ffc\u0013n\u0013,","rect":[310.6479187011719,311.48626708984377,415.5558403960274,286.9059143066406]},{"page":7,"text":"where σDC represents the DC conductivity, fc stands for the characteristic frequency, and","rect":[166.7686309814453,332.9581298828125,559.0118869305558,322.8567810058594]},{"page":7,"text":"n is a parameter, which represents the degree of interaction between the mobile ions and","rect":[167.18743896484376,345.4978332519531,559.0137179852433,335.44622802734377]},{"page":7,"text":"their surroundings. The value of n is normally situated between 0 and 1, however some","rect":[167.18743896484376,358.0375671386719,559.0193840829462,347.9859619140625]},{"page":7,"text":"authors have found values where n > 1 [33–36]. Many other models are available to analyze","rect":[167.18743896484376,370.5772705078125,559.0177982589248,360.5256652832031]},{"page":7,"text":"the frequency dependence of the complex conductivity like Cole–Cole, Cole–Davidson,","rect":[167.18743896484376,383.11700439453127,560.2586454838249,373.0653991699219]},{"page":7,"text":"Havriliak–Negami, or Kohlrausch–Williams–Watts functions transformed beforehand into","rect":[167.18743896484376,395.6567687988281,559.011517457045,385.60516357421877]},{"page":7,"text":"their conductivity representations [37–41]. Dyre’s approach based on a random free energy","rect":[167.18743896484376,408.19647216796877,559.400147925629,398.1448669433594]},{"page":7,"text":"barrier model can also be considered. The latter model is often applied for disordered ion","rect":[167.18743896484376,420.71630859375,559.0201013521593,410.6846008300781]},{"page":7,"text":"conducting solids and ionic liquids [42,43].","rect":[167.18743896484376,433.27593994140627,355.45299615774618,423.2442626953125]},{"page":7,"text":"Figure 4 illustrates the real component (σ’) of the complex conductivity (σ*) in homo-","rect":[188.43658447265626,445.8156433105469,560.6719660485794,435.7640380859375]},{"page":7,"text":"geneous and homeotropic alignments on a frequency range from 0.1 Hz to 1 MHz, obtained","rect":[167.18743896484376,458.35540771484377,559.0137874057524,448.3038024902344]},{"page":7,"text":"from Equation (6). The dielectric conductivity represents a process that combines jumps,","rect":[167.18743896484376,470.8951416015625,560.2587227317062,460.8435363769531]},{"page":7,"text":"mobility, and transport of charge carriers present in the material [4,36].","rect":[167.18743896484376,483.43487548828127,477.50789728079305,473.3832702636719]},{"page":7,"text":"HT cell","rect":[232.1093292236328,623.3255615234375,264.07834734584028,615.8084716796875]},{"page":7,"text":"HG cell","rect":[456.6451721191406,623.8051147460938,490.111489435684,616.2880249023438]},{"page":7,"text":"(a)","rect":[187.07028198242188,671.1384887695313,198.7411797047921,661.8197021484375]},{"page":7,"text":"(b)","rect":[408.7270812988281,671.1384887695313,420.9357903004952,661.5994873046875]},{"page":7,"text":"Figure 4. Real part of the complex conductivity in (a) homeotropic and (b) homogeneous alignments as a function of","rect":[57.23345184326172,691.2470703125,537.7703725119476,682.2005615234375]},{"page":7,"text":"frequency of non-purified, purified, and DNP-doped (0.05 wt%) LC mixtures. The experimental data are represented by","rect":[57.23345184326172,704.0554809570313,538.1199853750021,695.0089721679688]},{"page":7,"text":"symbols and the red lines show the curves obtained applying Jonscher’s model. NP corresponds to non-purified; P is for","rect":[57.23345184326172,716.8639526367188,537.9473732648393,707.8174438476563]},{"page":7,"text":"purified; and P + 0.05D stands for LC mixtures doped with 0.05 wt% of DNPs.","rect":[56.964576721191409,729.6544189453125,366.2963466424686,720.6258544921875]},{"page":7,"text":"The σ’ curves of NP- and P-LC mixtures in homogeneous and homeotropic alignments","rect":[188.43658447265626,752.3062744140625,559.0112754780201,742.2546997070313]},{"page":7,"text":"show two main regions: (1) a plateau region in the frequency range from 1 Hz to 1 kHz,","rect":[167.18743896484376,764.8460083007813,560.2585234135124,754.79443359375]},{"page":7,"text":"which is almost independent of frequency. Hence, the DC conductivity can be estimated by","rect":[166.7686309814453,777.3857421875,559.405030738129,767.3341674804688]},{"page":8,"text":"Molecules 2021,","rect":[35.983306884765628,60.788047790527347,88.35454684904119,53.726043701171878]},{"page":8,"text":"Sample","rect":[45.840736389160159,262.8171081542969,69.84736687042447,256.0108947753906]},{"page":8,"text":"NP","rect":[52.84248733520508,287.0237121582031,62.84525122903331,282.0705871582031]},{"page":8,"text":"P","rect":[55.7391471862793,300.0674133300781,59.94936957620128,295.2326965332031]},{"page":8,"text":"P + 0.05D","rect":[43.088008880615237,313.3479309082031,72.60138788636435,308.3948059082031]},{"page":8,"text":"P + 0.1D","rect":[44.830204010009769,326.5099792480469,70.85830011780966,321.5429382324219]},{"page":8,"text":"P + 0.2D","rect":[44.830204010009769,339.6720275878906,70.85830011780966,334.7189025878906]},{"page":8,"text":"26,","rect":[90.34609985351563,60.0,100.30400211027166,53.99673843383789]},{"page":8,"text":"2873","rect":[102.29560089111328,59.71322250366211,118.22841132503551,54.07635498046875]},{"page":8,"text":"8 of 13","rect":[536.0813598632813,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":8,"text":"the Jonscher’s power law; (2) at frequencies above 1 kHz, the conductivity is frequency","rect":[167.18743896484376,108.14791107177735,559.4054267747767,98.09632873535156]},{"page":8,"text":"dependent. According to Jonscher, this dependence may be due to relaxation phenomena","rect":[167.18743896484376,120.68770599365235,559.0154802446957,110.65602111816406]},{"page":8,"text":"originating from mobile charge carriers [44].","rect":[167.18743896484376,133.22744750976563,361.61702814016805,123.17585754394531]},{"page":8,"text":"At lower frequencies (<1 Hz), σ’ starts to decrease. This phenomenon is attributed","rect":[188.43658447265626,145.7472686767578,559.017414230437,135.71559143066407]},{"page":8,"text":"to electrode polarization. NP-LC mixtures exhibit the highest conductivity compared to","rect":[167.18743896484376,158.30691528320313,559.0194315413612,148.2752227783203]},{"page":8,"text":"the other samples. The fitting curves presented by red lines agree well to the experimental","rect":[167.18743896484376,170.84664916992188,559.0149156620178,160.79505920410157]},{"page":8,"text":"values for all samples. It is important to note that the conductivity values of the doped","rect":[166.9085693359375,183.38644409179688,559.014728683562,173.33485412597657]},{"page":8,"text":"samples are extremely low (in the range of 10−10 and 10−11 S·m−1), and almost at the level","rect":[167.18743896484376,195.92611694335938,559.0168770175378,184.25733947753907]},{"page":8,"text":"of sensitivity of the measuring device, explaining the noisy character of the spectra.","rect":[167.18743896484376,208.46481323242188,533.2130059233712,198.41322326660157]},{"page":8,"text":"The fitting results have been listed in Table 1.","rect":[188.43658447265626,221.00454711914063,386.5206536284493,210.9529571533203]},{"page":8,"text":"In the homeotropic alignment, n presents values greater than 1 (n > 1) for all samples.","rect":[188.43658447265626,371.9288635253906,560.7585455181443,361.87725830078127]},{"page":8,"text":"In the homogeneous alignment, n is greater than 1 as well for both P- and NP-LC mixtures.","rect":[167.18743896484376,384.4686279296875,560.7614438016168,374.4170227050781]},{"page":8,"text":"For the doped mixtures, the values of n are smaller than 1 and are therefore situated within","rect":[167.18743896484376,396.9884033203125,559.0138626365452,386.9566955566406]},{"page":8,"text":"the limits proposed by Jonscher.","rect":[167.18743896484376,409.54803466796877,308.07296075735555,399.516357421875]},{"page":8,"text":"The obtained values for n depend on sample nature and temperature. In our case,","rect":[188.43658447265626,422.06787109375,560.2590116947624,412.0361633300781]},{"page":8,"text":"although the temperature was identical for all experiments, the viscosity of the LC mixtures","rect":[167.18743896484376,434.6274719238281,559.0137779194264,424.57586669921877]},{"page":8,"text":"varied with the addition of DNPs. When n becomes smaller than 1, the process of charge","rect":[166.9085693359375,447.167236328125,559.0112690389108,437.1156311035156]},{"page":8,"text":"carrier displacement involves a translational motion with a sudden jump. When n > 1,","rect":[167.18743896484376,459.70697021484377,560.2605986088249,449.67529296875]},{"page":8,"text":"the movement involves a localized jump of the charge carriers that will leave their neigh-","rect":[167.18743896484376,472.2467346191406,560.6729196662959,462.19512939453127]},{"page":8,"text":"borhood completely [36]. Some research groups reported about n values with n > 1.","rect":[167.18743896484376,484.78643798828127,560.7573027103874,474.7547607421875]},{"page":8,"text":"Models were developed for this case like that of Kılıç et al. [35], designated as Super Linear","rect":[167.18743896484376,497.326171875,559.2173443611567,487.2745666503906]},{"page":8,"text":"Power Law (SLPL), and the Quantum Mechanical Tunneling (QMT) model for the case","rect":[167.18743896484376,509.8658752441406,559.0194451181025,499.81427001953127]},{"page":8,"text":"0.7 ≤ n ≤ 1.","rect":[167.18743896484376,521.0094604492188,219.48612298880085,512.6923828125]},{"page":8,"text":"The variation of the DC conductivity as a function of the concentration of DNPs is","rect":[188.43658447265626,534.9453125,559.0197623499422,524.8937377929688]},{"page":8,"text":"presented in Figure 5. The DC conductivity of purified LCs decreases significantly with","rect":[166.88856506347657,547.4840698242188,559.0150324480633,537.4324951171875]},{"page":8,"text":"the addition of DNPs for both alignments. There is a decrease of about 98% between the","rect":[167.18743896484376,560.0238037109375,559.0189716281038,549.9722290039063]},{"page":8,"text":"purified sample and the one doped with 0.05% DNPs. For the three concentrations of","rect":[166.88856506347657,572.5436401367188,559.0151402961736,562.511962890625]},{"page":8,"text":"nanoparticles, the decreases are small, and the σDC values are close together. However, this","rect":[167.18743896484376,585.1032104492188,559.0198203998951,575.071533203125]},{"page":8,"text":"means that the number of mobile ions decreases when the concentration of nanoparticles","rect":[167.18743896484376,597.6231079101563,559.0116553852961,587.5914306640625]},{"page":8,"text":"increases. The origin of this decrease is due to the adsorption of anions and cations on the","rect":[167.18743896484376,610.1826782226563,559.0188414507203,600.131103515625]},{"page":8,"text":"surface of the spherical DNPs.","rect":[167.18743896484376,622.7025146484375,299.96715631399618,612.6708374023438]},{"page":9,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":9,"text":"9 of 13","rect":[536.0813598632813,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":9,"text":"Figure 5. Variation of DC conductivity as a function of concentration of DNPs added to a purified","rect":[167.18743896484376,319.9040222167969,559.0119961955699,310.8575439453125]},{"page":9,"text":"LC mixture.","rect":[167.18743896484376,330.3568115234375,214.64250753114053,323.8361511230469]},{"page":9,"text":"The range of electrical conductivity of thermotropic LCs is comprised between 10−7–","rect":[188.43658447265626,355.3473815917969,560.5103532915707,343.7164611816406]},{"page":9,"text":"10−13 S·m−1, depending on the LC material. The values of electrical conductivity for","rect":[166.68966674804688,367.8871765136719,559.2183693370997,356.21832275390627]},{"page":9,"text":"the well-known LCs 5CB and E7 are generally in the range from 10−7 to 10−8 S·m−1 [8].","rect":[167.18743896484376,380.4258728027344,560.7592558353874,368.7580871582031]},{"page":9,"text":"Purified LCs from our work present a σDC// of 5.1 × 10−9 and a σDC ⊥ of 2.5 × 10−9 S·m−1.","rect":[167.18743896484376,393.1004638671875,560.758736140121,381.29779052734377]},{"page":9,"text":"These values are therefore situated within the range of conventional nematic LCs mixtures.","rect":[166.8785858154297,405.50531005859377,560.7451954765426,395.4537048339844]},{"page":9,"text":"3. Materials and Methods","rect":[167.18743896484376,425.2503967285156,283.3871027191259,417.9256591796875]},{"page":9,"text":"3.1. Materials","rect":[167.18743896484376,438.6961364746094,223.92800630856238,431.2320861816406]},{"page":9,"text":"The recycled LCs mixtures were supplied by the French recycling company ENVIE2E,","rect":[188.43658447265626,456.8590087890625,560.2612347491245,445.22802734375]},{"page":9,"text":"Lesquin, France. An orderly and manual dismantling line of LCD panels is set up for","rect":[167.18743896484376,469.3987121582031,559.2124489269435,459.34710693359377]},{"page":9,"text":"recycling purposes. In order to extract LCs, end-of-life LCD panels (Figure 6a,b) are","rect":[167.18743896484376,481.9384460449219,559.0193840829462,471.8868408203125]},{"page":9,"text":"opened and exposed to a bath of an ultrasonic activated organic solvent. The details of the","rect":[167.18743896484376,494.4781799316406,559.0114533997445,484.42657470703127]},{"page":9,"text":"extraction process are described in a patent [45]. The advantages of this extraction method","rect":[167.18743896484376,507.01788330078127,559.0132867646173,496.9662780761719]},{"page":9,"text":"lie in the recovery speed of LC molecules, and the relatively low contamination effects.","rect":[167.18743896484376,519.5575561523438,548.0800713530587,509.5059814453125]},{"page":9,"text":"Figure 6. (a) End-of-life LCD, (b) LCD display composition, (c) Non-purified and (d) purified LCs mixtures, and (e) Texture","rect":[57.23345184326172,699.9078369140625,537.770654464477,690.861328125]},{"page":9,"text":"of purified LC mixtures observed under polarizing optical microscope (POM) Olympus BX60 (Olympus Corporation, Tokyo,","rect":[57.23345184326172,712.71630859375,538.8842259527216,703.6697998046875]},{"page":9,"text":"Japan), presenting a nematic Schlieren texture. Conditions: LC sample sandwiched between un-aligned glass and coverslip;","rect":[57.081520080566409,725.5247802734375,538.8901363387149,716.4961547851563]},{"page":9,"text":"crossed polarizers; and room temperature.","rect":[57.23345184326172,738.3152465820313,225.00664327332803,729.3045654296875]},{"page":9,"text":"The resulting solution contains LC molecules, the organic solvent, as well as organic","rect":[188.43658447265626,760.9671020507813,559.0160284885375,750.9354248046875]},{"page":9,"text":"and inorganic impurities, especially ions. The solid impurities were filtered out, followed","rect":[167.18743896484376,773.5068359375,559.0201364945287,763.4552612304688]},{"page":10,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":10,"text":"10 of 13","rect":[532.09814453125,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":10,"text":"by evaporation of the solvent under primary vacuum (solvent recycling). The samples","rect":[167.18743896484376,108.14791107177735,559.0195182093172,98.09632873535156]},{"page":10,"text":"containing the recovered LCs present an atypical green-black color (shown in Figure 6c).","rect":[167.18743896484376,120.68770599365235,560.757550238523,110.65602111816406]},{"page":10,"text":"This color might be attributed to the dissolution of the glue used to assemble the two glass","rect":[166.8785858154297,133.22744750976563,559.0169442712339,123.17585754394531]},{"page":10,"text":"plates into the LCD slab and/or other materials dissolved during the extraction process. In","rect":[166.88856506347657,145.76718139648438,559.0175247459202,135.73548889160157]},{"page":10,"text":"order to increase the purity of the LC mixtures, other purification steps are necessary.","rect":[167.18743896484376,158.30691528320313,541.0499199858712,148.2553253173828]},{"page":10,"text":"Three different LC mixtures were used in this study. Each mixture corresponds to","rect":[188.43658447265626,170.84664916992188,559.0197977522987,160.79505920410157]},{"page":10,"text":"a recovery period of 4 months during one year, thus: Mixture 1 (1–4 months), Mixture 2","rect":[167.18743896484376,183.38644409179688,559.0193661629625,173.33485412597657]},{"page":10,"text":"(5–8 months), and Mixture 3 (8–12 months). It should be noted that these mixtures were","rect":[166.85858154296876,195.24937438964845,559.0167502087913,185.89442443847657]},{"page":10,"text":"extracted from a large number of end-of-life LCD screens exhibiting highly heterogeneous","rect":[167.18743896484376,208.46481323242188,559.0176587565361,198.41322326660157]},{"page":10,"text":"nature: televisions, computers, and tablets with totally different types, sizes, brands, and","rect":[167.18743896484376,221.00460815429688,559.0193106966439,210.95301818847657]},{"page":10,"text":"years of production.","rect":[166.9085693359375,233.54428100585938,255.63417901907429,223.49269104003907]},{"page":10,"text":"3.2. Purification and Characterization of LC Mixtures","rect":[167.18743896484376,255.866943359375,384.5502597265311,245.83526611328126]},{"page":10,"text":"Several distillation and chromatographic steps were used to remove the remaining","rect":[188.43658447265626,271.4621887207031,559.0198066575892,261.4305114746094]},{"page":10,"text":"impurities from the recycled LCs mixtures. The purified LCs present a nematic phase at","rect":[167.18743896484376,284.0018615722656,559.0208719779561,273.95025634765627]},{"page":10,"text":"room temperature (Figure 6c,e) and the clearing temperature is situated around 80 ◦C.","rect":[167.18743896484376,296.5416564941406,545.4380425444649,286.5099792480469]},{"page":10,"text":"3.3. Addition of DNPs to Purified LC Mixtures","rect":[167.18740844726563,318.86431884765627,358.4801913671561,308.8326416015625]},{"page":10,"text":"The DNPs used in this study present an average size of diameter lower than 10 nm.","rect":[188.43658447265626,334.45953369140627,560.7564738686289,324.4079284667969]},{"page":10,"text":"They were purchased from Sigma-Aldrich (Saint-Quentin Fallavier, France) and no further","rect":[166.8785858154297,346.999267578125,559.2132074465854,336.9476623535156]},{"page":10,"text":"purification has been performed. These DNP were added to purified LCs at three different","rect":[166.88856506347657,359.5190734863281,559.012682023524,349.48736572265627]},{"page":10,"text":"concentrations: 0.05; 0.1; and 0.2 wt%. Before use, to ensure good dispersion, these mixtures","rect":[167.18743896484376,372.0787048339844,559.0138389545826,362.027099609375]},{"page":10,"text":"were placed in an ultrasonic bath (Elmasonic S30H, Elma Schmidbauer GmbH, Singen,","rect":[166.7686309814453,384.618408203125,560.2562651127312,374.58673095703127]},{"page":10,"text":"Germany) for 30 min at room temperature. On the time scale applied for the dielectric","rect":[167.18743896484376,397.1581726074219,559.0193529144294,387.1065673828125]},{"page":10,"text":"experiments, phase separation effects between LC and DNPs were not observed on a","rect":[167.18743896484376,409.6780090332031,559.019488233275,399.64630126953127]},{"page":10,"text":"macroscopic scale.","rect":[167.18743896484376,422.21771240234377,248.22548761282429,412.2059326171875]},{"page":10,"text":"3.4. Dielectric Measurements","rect":[167.18743896484376,441.99261474609377,285.8168612890311,434.528564453125]},{"page":10,"text":"The real and imaginary components (ε’ and ε”) of the complex dielectric function of","rect":[188.43658447265626,460.1545104980469,559.0129057569384,450.1029052734375]},{"page":10,"text":"NP, P, and DNP doped LC mixtures were measured. In this report, relative permittivities","rect":[167.18743896484376,472.67431640625,559.0208325852938,462.66253662109377]},{"page":10,"text":"will be considered. The measurements were performed at room temperature (20 ◦C) in a","rect":[166.7686309814453,485.21405029296877,559.0188669677048,475.1823425292969]},{"page":10,"text":"frequency range from 0.1 Hz to 1 MHz with an impedance analyzer ModuLab-MTS test","rect":[167.18743896484376,497.773681640625,559.0208719779561,487.7220764160156]},{"page":10,"text":"system from Solartron Analytical, Ametek, Berwyn, PA, USA. For preliminary tests, two","rect":[167.18743896484376,510.31341552734377,559.0137208651216,500.2618103027344]},{"page":10,"text":"amplitudes of the oscillating voltage were tested: 0.1 and 1 V.","rect":[167.18743896484376,522.8530883789063,435.95320978079305,512.801513671875]},{"page":10,"text":"The measurements were performed using commercial (standard) cells of 20 µm thick-","rect":[188.43658447265626,535.392822265625,560.6710519572285,525.3412475585938]},{"page":10,"text":"ness manufactured by AWAT, Warsaw, Poland. These cells are composed of two glass","rect":[167.18743896484376,547.9325561523438,559.0193961390047,537.8809814453125]},{"page":10,"text":"plates, each one is covered on its inner surface by a conductive coating (indium tin oxide:","rect":[166.88856506347657,560.4722900390625,560.2624535410428,550.4207153320313]},{"page":10,"text":"ITO), serving as electrode with a surface area of 0.25 cm2 and a sheet resistance of ~20 Ω/\u0003.","rect":[167.18743896484376,573.0120239257813,560.758736140121,561.382080078125]},{"page":10,"text":"ITO electrodes are widely used for dielectric measurements and LCs devices. They are","rect":[167.18743896484376,585.5518188476563,559.0195061532587,575.500244140625]},{"page":10,"text":"transparent to visible light and chemically stable [46,47]. The cells are also coated with","rect":[167.18743896484376,598.0914916992188,559.0126520769695,588.059814453125]},{"page":10,"text":"polyimide to obtain homogeneous and homeotropic alignments. NP, P, and doped LC","rect":[166.88856506347657,610.6312255859375,559.0152554085339,600.5995483398438]},{"page":10,"text":"mixtures were inserted into the cells by capillary action at a temperature of 90 ◦C, where","rect":[167.18743896484376,623.1709594726563,559.0184476019362,613.119384765625]},{"page":10,"text":"the LCs present an isotropic phase. Figure 7 illustrates the textures of a P LC mixture in","rect":[167.18743896484376,635.710693359375,559.0194269793133,625.6591186523438]},{"page":10,"text":"homogeneous and homeotropic alignments, using the same cells employed for dielectric","rect":[167.18743896484376,648.2504272460938,559.0137471379187,638.1988525390625]},{"page":10,"text":"measurements.","rect":[167.18743896484376,658.1727905273438,233.79637994680867,651.803466796875]},{"page":10,"text":"The uniform and bright color throughout the texture exhibited in Figure 7a confirms","rect":[188.43658447265626,673.3298950195313,559.0128942765063,663.2783203125]},{"page":10,"text":"the homogeneous alignment of the LCs in the cell. In contrast, Figure 7b reveals a totally","rect":[167.18743896484376,685.8695678710938,559.4079043844939,675.8179931640625]},{"page":10,"text":"dark micrograph corroborating the homeotropic alignment of LCs.","rect":[167.18743896484376,698.4093017578125,460.10140314016805,688.3577270507813]},{"page":11,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":11,"text":"HG cell","rect":[249.98265075683595,124.76838684082031,290.84170146001619,115.7479019165039]},{"page":11,"text":"HT cell","rect":[425.4372253417969,124.76838684082031,464.49950785650057,115.7479019165039]},{"page":11,"text":"11 of 13","rect":[532.09814453125,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":11,"text":"(a)","rect":[224.07479858398438,214.86965942382813,238.88029148126689,203.6871337890625]},{"page":11,"text":"100 µm","rect":[258.1148986816406,198.3212890625,304.2569150008811,185.7515106201172]},{"page":11,"text":"100 µm","rect":[428.8197021484375,196.30743408203126,474.961718467678,183.73765563964845]},{"page":11,"text":"(b)","rect":[398.8816223144531,216.23648071289063,414.3325009539231,204.7897186279297]},{"page":11,"text":"Figure 7. Textures of a purified LC mixture in (a) homogeneous and (b) homeotropic alignments.","rect":[167.18743896484376,236.82192993164063,560.5846271336529,227.7754364013672]},{"page":11,"text":"The micrographs are recorded by POM under cross-polarized condition at room temperature.","rect":[166.90957641601563,249.63027954101563,536.8259486932499,240.60169982910157]},{"page":11,"text":"4. Conclusions","rect":[167.18743896484376,267.5272216796875,234.15486394959465,260.2024841308594]},{"page":11,"text":"The dielectric properties of non-purified, purified, and doped recycled LC mix-","rect":[188.43658447265626,285.7001037597656,560.6653478157049,275.64849853515627]},{"page":11,"text":"tures with different DNP concentrations (0.05, 0.1, and 0.2 wt%), in homogeneous and","rect":[167.18743896484376,298.2398376464844,559.019367355437,288.188232421875]},{"page":11,"text":"homeotropic alignments, have been investigated at room temperature using an impedance","rect":[167.18743896484376,310.7795715332031,559.019107232101,300.7478942871094]},{"page":11,"text":"analyzer. Non-purified LC mixtures show positive values of dielectric anisotropy in the","rect":[167.18743896484376,323.3183288574219,559.0194451181025,313.2667236328125]},{"page":11,"text":"frequency range comprised between 20 and 105 Hz. It has been demonstrated that a","rect":[167.18743896484376,335.8580322265625,559.015093702025,324.22808837890627]},{"page":11,"text":"purification process is mandatory to improve the dielectric properties of these recycled","rect":[166.88856506347657,348.39776611328127,559.015216964812,338.3461608886719]},{"page":11,"text":"LC mixtures. The addition of DNPs to these LC mixtures allowed to decrease the ionic","rect":[167.18743896484376,358.32012939453127,559.0194139495857,350.88592529296877]},{"page":11,"text":"conductivity due to the trapping of ionic impurities on their surface. A small amount of","rect":[167.18743896484376,373.4772644042969,559.020857330531,363.4256591796875]},{"page":11,"text":"DNPs (0.05 wt%) has been shown to reduce the ionic conductivity of the sample by two","rect":[167.18743896484376,386.0169372558594,559.0194315413612,375.96533203125]},{"page":11,"text":"orders of magnitude, regardless of the anchoring conditions, compared to the non-purified","rect":[167.18743896484376,398.5566711425781,559.011612300663,388.50506591796877]},{"page":11,"text":"samples. Consequently, such recycled LC material could be upgraded for other uses (LC","rect":[167.18743896484376,411.0964050292969,559.0199706407166,401.0447998046875]},{"page":11,"text":"screens, smart windows).","rect":[167.18743896484376,422.9593505859375,278.6371392241524,413.60443115234377]},{"page":11,"text":"Supplementary Materials: Figure S1: Relative permittivity of three purified LC mixtures as a","rect":[167.18743896484376,447.3151550292969,559.0166053415246,438.2686767578125]},{"page":11,"text":"function of frequency. Measurements were taken at 1 V and room temperature (20 ◦C) using 20 µm","rect":[167.18743896484376,459.3324279785156,559.0159341160593,450.28594970703127]},{"page":11,"text":"cells in homogeneous and homeotropic alignments. P stands for purified LC mixtures.","rect":[167.18743896484376,471.3497009277344,508.7832851190311,462.30322265625]},{"page":11,"text":"Author Contributions: Conceptualization, U.M. and A.B.; methodology, A.B., U.M., C.B. and F.D.;","rect":[166.8376007080078,489.0249938964844,560.1324705550806,479.9964294433594]},{"page":11,"text":"software, F.D. and P.-A.H.; validation, A.B., C.B. and F.D.; investigation, A.B.; data curation, A.B.;","rect":[167.18743896484376,500.7286071777344,560.1341266453717,491.68212890625]},{"page":11,"text":"writing—original draft preparation, U.M., P.S., C.F. and A.B.; writing—review and editing, all authors.","rect":[166.8106231689453,512.4322509765625,560.5872899175654,503.3857421875]},{"page":11,"text":"All authors have read and agreed to the published version of the manuscript.","rect":[166.8376007080078,524.1358642578125,472.1363124627811,515.08935546875]},{"page":11,"text":"Funding: This research was funded by Région Hauts-de-France (FEDER), l’I-Site Lille and ENVIE2E","rect":[167.18743896484376,541.8111572265625,559.0158841404403,531.2338256835938]},{"page":11,"text":"du Nord.","rect":[167.18743896484376,551.1590576171875,203.74442098328897,544.4861450195313]},{"page":11,"text":"Data Availability Statement: Data set presented in this study is available in this article.","rect":[167.18743896484376,571.1890869140625,513.3527431268436,562.1604614257813]},{"page":11,"text":"Acknowledgments: The authors acknowledge financial support from the University of Lille, the","rect":[166.83761596679688,588.8643798828125,559.0143313790946,579.81787109375]},{"page":11,"text":"Région Hauts-de-France (FEDER), I-Site of Lille and ENVIE2E du Nord.","rect":[166.89157104492188,600.5052490234375,443.2693691034061,589.9906616210938]},{"page":11,"text":"Conflicts of Interest: All authors declare no conflict of interest.","rect":[167.1874542236328,615.8875732421875,415.95058248231239,609.19677734375]},{"page":11,"text":"Sample Availability: Samples of the compounds are currently under use for other applications.","rect":[167.1874542236328,635.9185791015625,545.6254482049686,626.8720703125]},{"page":11,"text":"References","rect":[35.983306884765628,655.9442749023438,85.76325475770013,648.6195678710938]},{"page":11,"text":"1.","rect":[35.983306884765628,670.2826538085938,42.70498845765418,664.048583984375]},{"page":11,"text":"2.","rect":[35.983306884765628,693.2723388671875,42.70498845765418,687.0830688476563]},{"page":11,"text":"3.","rect":[35.983306884765628,716.4141845703125,42.70498845765418,710.0726928710938]},{"page":11,"text":"4.","rect":[35.983306884765628,739.2516479492188,42.70498845765418,733.017578125]},{"page":11,"text":"5.","rect":[35.983306884765628,762.3925170898438,42.70498845765418,756.051025390625]},{"page":11,"text":"Collings, P.J.; Hird, M. Introduction to Liquid Crystals: Chemistry and Physics, 1st ed.; Taylor & Francis Ltd.: London, UK, 2017; ISBN","rect":[57.48833084106445,672.7905883789063,559.0148574965341,663.6992797851563]},{"page":11,"text":"9781351989244.","rect":[57.48833084106445,681.9296875,117.98346517274207,675.5433959960938]},{"page":11,"text":"Yang, D.K.; Wu, S.T. Fundamentals of Liquid Crystal Devices, 1st ed.; John Wiley & Sons Ltd.: Chichester, UK, 2014; ISBN","rect":[57.48833084106445,695.7802734375,559.0186338442155,686.68896484375]},{"page":11,"text":"9781118751992.","rect":[57.48833084106445,704.9193725585938,117.98346517274207,698.5330810546875]},{"page":11,"text":"Oswald, P.; Pieranski, P. Nematic and Cholesteric Liquid Crystals, 1st ed.; CRC Press Taylor & Francis Group: Boca Raton, FL, USA,","rect":[57.48833084106445,718.7698974609375,560.1389035948679,709.6785888671875]},{"page":11,"text":"2005.","rect":[57.48833084106445,727.9089965820313,77.65337178895301,721.5675048828125]},{"page":11,"text":"Kremer, F.; Schönhals, A. Broadband Dielectric Spectroscopy, 1st ed.; Springer: Berlin/Heidelberg, Germany; New York, NY, USA,","rect":[57.48833084106445,741.7595825195313,560.1403662885903,732.6682739257813]},{"page":11,"text":"2003; ISBN 9783540434078.","rect":[57.48833084106445,752.0889892578125,163.2786311883671,744.3770751953125]},{"page":11,"text":"Bulja, S.; Mirshekar-Syahkal, D.; James, R.; Day, S.E.; Fernandez, F.A. Measurement of Dielectric Properties of Nematic Liquid","rect":[57.48833084106445,764.7482299804688,559.0163554536902,755.7017211914063]},{"page":11,"text":"Crystals at Millimeter Wavelength. IEEE Trans. Microw. Theory Tech. 2010, 58, 3493–3501. [CrossRef]","rect":[57.48833084106445,776.2431030273438,449.5921841672214,767.1517944335938]},{"page":12,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":12,"text":"12 of 13","rect":[532.09814453125,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":12,"text":"6.","rect":[35.983306884765628,105.51161193847656,42.70498845765418,99.17011260986328]},{"page":12,"text":"7.","rect":[35.983306884765628,139.84286499023438,42.70498845765418,133.65362548828126]},{"page":12,"text":"8.","rect":[35.98332214355469,162.98487854003907,42.705003716443247,156.64337158203126]},{"page":12,"text":"9.","rect":[35.983306884765628,185.9745635986328,42.70498845765418,179.633056640625]},{"page":12,"text":"10.","rect":[35.983306884765628,208.96424865722657,47.1861095208866,202.57797241210938]},{"page":12,"text":"11.","rect":[35.98329162597656,231.80166625976563,47.18609426209754,225.56765747070313]},{"page":12,"text":"12.","rect":[35.98332214355469,254.79031372070313,47.186124779675669,248.55630493164063]},{"page":12,"text":"13.","rect":[35.98332214355469,266.4374084472656,47.186124779675669,260.0511169433594]},{"page":12,"text":"14.","rect":[35.983314514160159,289.2747497558594,47.186117150281138,283.0407409667969]},{"page":12,"text":"15.","rect":[35.98331069946289,312.4167785644531,47.18611333558387,306.0304870605469]},{"page":12,"text":"16.","rect":[35.983306884765628,335.4054870605469,47.1861095208866,329.0191955566406]},{"page":12,"text":"17.","rect":[35.98333740234375,346.7480163574219,47.18614003846473,340.5140075683594]},{"page":12,"text":"18.","rect":[35.98332214355469,369.8899230957031,47.186124779675669,363.5036315917969]},{"page":12,"text":"19.","rect":[35.98329544067383,392.87957763671877,47.186098076794809,386.4932861328125]},{"page":12,"text":"20.","rect":[35.98332214355469,415.8692626953125,47.186124779675669,409.5277404785156]},{"page":12,"text":"21.","rect":[35.98332214355469,438.7056579589844,47.186124779675669,432.4716491699219]},{"page":12,"text":"22.","rect":[35.983306884765628,461.6953125,47.1861095208866,455.5060729980469]},{"page":12,"text":"23.","rect":[35.983306884765628,484.8372802734375,47.1861095208866,478.4957580566406]},{"page":12,"text":"24.","rect":[35.983314514160159,507.6746520996094,47.186117150281138,501.4406433105469]},{"page":12,"text":"25.","rect":[35.983306884765628,530.8156127929688,47.1861095208866,524.47412109375]},{"page":12,"text":"26.","rect":[35.98329162597656,565.300048828125,47.18609426209754,558.9585571289063]},{"page":12,"text":"27.","rect":[35.98332214355469,588.1375732421875,47.186124779675669,581.9483032226563]},{"page":12,"text":"28.","rect":[35.98329162597656,611.2794189453125,47.18609426209754,604.9379272460938]},{"page":12,"text":"29.","rect":[35.98332214355469,634.2681274414063,47.186124779675669,627.9266357421875]},{"page":12,"text":"30.","rect":[35.98332214355469,645.762939453125,47.186124779675669,639.4214477539063]},{"page":12,"text":"31.","rect":[35.983306884765628,668.7526245117188,47.1861095208866,662.3663330078125]},{"page":12,"text":"32.","rect":[35.983306884765628,691.7423095703125,47.1861095208866,685.4008178710938]},{"page":12,"text":"33.","rect":[35.98332214355469,703.2371215820313,47.186124779675669,696.8956298828125]},{"page":12,"text":"34.","rect":[35.983306884765628,737.7206420898438,47.1861095208866,731.3343505859375]},{"page":12,"text":"35.","rect":[35.98332214355469,760.7103271484375,47.186124779675669,754.3688354492188]},{"page":12,"text":"LCD Waste Recycling System-Circular Economy-Sustainable Environment-Innovations & Applications-Industrial Technology","rect":[57.48833084106445,107.86727905273438,559.3688352218597,98.83870697021485]},{"page":12,"text":"Research Institute.","rect":[57.48833084106445,117.00648498535156,132.64962957505919,110.33358001708985]},{"page":12,"text":"Available online:","rect":[137.63174438476563,117.00648498535156,206.22946355943419,110.33358001708985]},{"page":12,"text":"https://www.itri.org.tw/english/ListStyle.aspx?DisplayStyle=01_content&SiteID=1&","rect":[210.4711151123047,119.36215209960938,559.7124187219591,110.33358001708985]},{"page":12,"text":"MmmID=1037333532432522160&MGID=1037350654202216363 (accessed on 30 March 2021).","rect":[57.48833084106445,130.24795532226563,421.18507955262489,121.82845306396485]},{"page":12,"text":"Garbovskiy, Y. Switching between purification and contamination regimes governed by the ionic purity of nanoparticles dispersed","rect":[57.48833084106445,142.35079956054688,559.0148490097016,133.30430603027345]},{"page":12,"text":"in liquid crystals. Appl. Phys. Lett. 2016, 108, 121104. [CrossRef]","rect":[57.48833084106445,153.84567260742188,307.68541536839327,144.75439453125]},{"page":12,"text":"Garbovskiy, Y.; Glushchenko, I. Nano-Objects and Ions in Liquid Crystals: Ion Trapping Effect and Related Phenomena. Crystals","rect":[57.48833084106445,165.34054565429688,559.0162756042381,156.249267578125]},{"page":12,"text":"2015, 5, 501–533. [CrossRef]","rect":[57.48833084106445,175.9486846923828,166.70201693089323,167.78892517089845]},{"page":12,"text":"Garbovskiy, Y. Conventional and unconventional ionic phenomena in tunable soft materials made of liquid crystals and","rect":[57.48833084106445,188.33023071289063,559.0174554236321,179.2837371826172]},{"page":12,"text":"nanoparticles. Nano Express 2021, 2, 012004. [CrossRef]","rect":[57.48833084106445,199.80712890625,273.2793789914401,190.77854919433595]},{"page":12,"text":"Osipov, M.A.; Gorkunov, M.V.; Lagerwall, J.P.F.; Scalia, G. Nematic liquid crystals doped with nanoparticles: Phase behavior and","rect":[57.48833084106445,211.31991577148438,559.0189566702999,202.2913360595703]},{"page":12,"text":"dielectric properties. Ser. Soft Condens. Matter 2016, 1–2, 135–175. [CrossRef]","rect":[57.48833084106445,222.79681396484376,356.7348843625339,213.72344970703126]},{"page":12,"text":"Podgornov, F.V.; Wipf, R.; Stühn, B.; Ryzhkova, A.V.; Haase, W.Low-frequencyrelaxationmodesinferroelectricliquidcrystal/gold","rect":[57.48833084106445,234.30856323242188,559.0147269393891,225.26206970214845]},{"page":12,"text":"nanoparticle dispersion: Impact of nanoparticle shape. Liq. Cryst. 2016, 43, 1536–1547. [CrossRef]","rect":[57.48833084106445,245.7855224609375,440.844289880112,236.75694274902345]},{"page":12,"text":"Basu, R. Soft memory in a ferroelectric nanoparticle-doped liquid crystal. Phys. Rev. E 2014, 89, 022508. [CrossRef]","rect":[57.492706298828128,257.2982482910156,507.468801598862,248.20697021484376]},{"page":12,"text":"Tang, C.-Y.; Huang, S.-M.; Lee, W. Electrical properties of nematic liquid crystals doped with anatase TiO2 nanoparticles. J. Phys.","rect":[57.48833084106445,268.7931213378906,560.1320420184027,259.70184326171877]},{"page":12,"text":"D Appl. Phys. 2011, 44. [CrossRef]","rect":[57.139495849609378,280.2251892089844,190.08457003147917,271.19659423828127]},{"page":12,"text":"Yadav, G.; Katiyar, R.; Pathak, G.; Manohar, R. Effect of ion trapping behavior of TiO2 nanoparticles on different parameters of","rect":[57.48833084106445,291.7826843261719,559.0150766523044,282.7362060546875]},{"page":12,"text":"weakly polar nematic liquid crystal. J. Theor. Appl. Phys. 2018, 12, 191–198. [CrossRef]","rect":[57.11250305175781,303.2775573730469,394.5823575070651,294.186279296875]},{"page":12,"text":"Prakash, J.; Khan, S.; Chauhan, S.; Biradar, A. Metal oxide-nanoparticles and liquid crystal composites: A review of recent","rect":[57.48833084106445,314.7724304199219,559.0173562236897,305.7259521484375]},{"page":12,"text":"progress. J. Mol. Liq. 2020, 297, 112052. [CrossRef]","rect":[57.219459533691409,326.2673034667969,253.90436373265104,317.176025390625]},{"page":12,"text":"Porov, P.; Chandel, V.S. Carbon Nanotube Doped Liquid Crystals. J. Sci. Arts. 2016, 3, 249–264.","rect":[57.49269104003906,337.7611389160156,429.587942101453,328.7325744628906]},{"page":12,"text":"Tomylko, S.; Yaroshchuk, O.; Kovalchuk, O.; Maschke, U.; Yamaguchi, R. Dielectric and Electro-Optical Properties of Liquid","rect":[57.48833084106445,349.25592041015627,559.0174554236321,340.2094421386719]},{"page":12,"text":"Crystals Doped with Diamond Nanoparticles. Mol. Cryst. Liq. Cryst. 2011, 541, 35–273. [CrossRef]","rect":[57.48833084106445,360.750732421875,443.49742708714327,351.6594543457031]},{"page":12,"text":"Tomylko, S.; Yaroshchuk, O.; Kovalchuk, O.; Maschke, U.; Yamaguchi, R. Dielectric properties of nematic liquid crystal modified","rect":[57.48833084106445,372.2455749511719,559.0203699576555,363.1990966796875]},{"page":12,"text":"with diamond nanoparticles. Ukr. J. Phys. 2012, 57, 239–243.","rect":[57.11250305175781,383.72247314453127,292.97829244324989,374.64910888671877]},{"page":12,"text":"Agrahari, K.; Pathak, G.; Vimal, T.; Kurp, K.; Srivastava, A.; Manohar, R. Dielectric and spectroscopic study of nano-sized","rect":[57.48833084106445,395.2352600097656,559.0175164587884,386.18878173828127]},{"page":12,"text":"diamond dispersed ferroelectric liquid crystal. J. Mol. Liq. 2018, 264, 510–514. [CrossRef]","rect":[57.48833084106445,406.7301025390625,405.7851162961276,397.6388244628906]},{"page":12,"text":"Gaur, D.K.; Rastogi, A.; Trivedi, H.; Parmar, A.S.; Manohar, R.; Singh, S. Investigation of dielectric and optical properties of pure","rect":[57.48833084106445,418.22491455078127,559.0124157048298,409.1784362792969]},{"page":12,"text":"and diamond nanoparticles dispersed nematic liquid-crystal PCH5. Liq. Cryst. 2020, 48, 1–11. [CrossRef]","rect":[57.48833084106445,429.7197570800781,469.7469082883151,420.67327880859377]},{"page":12,"text":"Wilkinson, T.D.; Butt, H.; Montelongo, Y. Holographic Liquid Crystals for Nanophotonics. In Nanosciense and Technology; Quan,","rect":[57.48833084106445,441.2135925292969,560.1377417768715,432.122314453125]},{"page":12,"text":"L., Ed.; Springer International Publishing: Cham, Switzerland, 2014; pp. 1–33.","rect":[57.48833084106445,452.7084045410156,364.45396993348427,443.6798400878906]},{"page":12,"text":"Mochalin, V.N.; Shenderova, O.; Ho, D.; Gogotsi, Y. The properties and applications of nanodiamonds. Nat. Nanotechnol. 2011, 7,","rect":[57.48833084106445,464.2032775878906,560.13682052542,455.11199951171877]},{"page":12,"text":"11–23. [CrossRef]","rect":[57.04054260253906,474.8113708496094,125.92432985813932,466.651611328125]},{"page":12,"text":"Hadjichristov, G.B.; E Vlakhov, T.; Marinov, Y.G. Impedance and dielectric spectroscopy study of graphene-doped liquid crystal","rect":[57.48833084106445,487.19293212890627,559.0174411823361,478.1464538574219]},{"page":12,"text":"E7. J. Phys. Conf. Ser. 2019, 1186, 012032. [CrossRef]","rect":[57.48833084106445,498.6250915527344,259.809621911362,489.59649658203127]},{"page":12,"text":"Perkowski, P.; Łada, D.; Ogrodnik, K.; Rutkowska, J.; Piecek, W.; Raszewski, Z. Technical aspects of dielectric spectroscopy","rect":[57.48833084106445,510.1825866699219,559.3648933624317,501.1361083984375]},{"page":12,"text":"measurements of liquid crystals. Opto-Electronics Rev. 2008, 16, 271–276. [CrossRef]","rect":[57.48833084106445,521.677490234375,384.4550381711276,512.586181640625]},{"page":12,"text":"Buivydas, M.; Gouda, F.; Andersson, G.; Lagerwall, S.T.; Stebler, B.; Bomelburg, J.; Heppke, G.; Gestblom, B. Collective and","rect":[57.48833084106445,533.1713256835938,559.0175774939446,524.1427001953125]},{"page":12,"text":"non-collective excitations in antiferroelectric and ferrielectric liquid crystals studied by dielectric relaxation spectroscopy and","rect":[57.48833084106445,544.6661376953125,559.0175239480267,535.61962890625]},{"page":12,"text":"electro-optic measurements. Liq. Cryst. 1997, 23, 723–739. [CrossRef]","rect":[57.48833084106445,556.14306640625,327.3664761594089,547.114501953125]},{"page":12,"text":"Dhar, R. An impedance model to improve the higher frequency limit of electrical measurements on the capacitor cell made from","rect":[57.48833084106445,567.65576171875,559.0129288091974,558.6092529296875]},{"page":12,"text":"electrodes of finite resistances. Indian J. Pure Appl. Phys. 2004, 42, 56–61.","rect":[57.48833084106445,579.087890625,339.57225606629677,570.059326171875]},{"page":12,"text":"Wojciechowski, M.; Ba˛k, G.W.; Tykarska, M. Dielectric properties of LC mixture with induced antiferroelectric phase. Opto-","rect":[57.48833084106445,590.6455078125,560.5040761252288,581.5989990234375]},{"page":12,"text":"Electronics Rev. 2008, 16, 257–261. [CrossRef]","rect":[57.2104606628418,601.2535400390625,231.61488924534636,593.0490112304688]},{"page":12,"text":"Perkowski, P. Dielectric spectroscopy of liquid crystals. Electrodes resistivity and connecting wires inductance influence on","rect":[57.48833084106445,613.6351318359375,559.0176110882378,604.588623046875]},{"page":12,"text":"dielectric measurements. Opto-Electronics Rev. 2012, 20, 180–186. [CrossRef]","rect":[57.48833084106445,625.0672607421875,354.56590853245577,616.0386962890625]},{"page":12,"text":"Merck. Liquid Crystal Mixtures for Electro-Optic Displays; Merck KGaA: Darmstadt, Germany, 1994.","rect":[57.492706298828128,636.6238403320313,442.74510762879677,627.5325317382813]},{"page":12,"text":"Kelly, S.; Oneill, M. Liquid crystals for electro-optic applications. In Handbook of Advanced Electronic and Photonic Materials and","rect":[57.48833084106445,648.11865234375,559.0143212683097,639.02734375]},{"page":12,"text":"Devices; Elsevier BV: Amsterdam, The Netherlands, 2001; Volume 7, pp. 1–66.","rect":[57.139495849609378,659.5955810546875,362.3297939080936,650.5848999023438]},{"page":12,"text":"Wang, W.; Rong, M.; Murphy, A.B.; Wu, Y.; Spencer, J.W.; Yan, J.D.; Fang, M.T.C. Thermophysical properties of carbon–argon and","rect":[57.48833084106445,671.1083374023438,559.0135418355908,662.0618286132813]},{"page":12,"text":"carbon–helium plasmas. J. Phys. D Appl. Phys. 2011, 44. [CrossRef]","rect":[57.48833084106445,682.585205078125,320.1612149289401,673.5118408203125]},{"page":12,"text":"Jonscher, A.K. The ‘universal’ dielectric response. Nature 1977, 267, 673–679. [CrossRef]","rect":[57.49269104003906,694.080078125,401.68004427464327,685.051513671875]},{"page":12,"text":"Prasad, S.K.; Kumar, M.V.; Shilpa, T.; Yelamaggad, C.V. Enhancement of electrical conductivity, dielectric anisotropy and director","rect":[57.48833084106445,705.5928344726563,559.1955414072136,696.5463256835938]},{"page":12,"text":"relaxation frequency in composites of gold nanoparticle and a weakly polar nematic liquid crystal. RSC Adv. 2014, 4, 4453–4462.","rect":[57.48833084106445,717.0877075195313,560.584198330038,707.9963989257813]},{"page":12,"text":"[CrossRef]","rect":[57.48833084106445,727.6947631835938,98.94766054661588,719.5350341796875]},{"page":12,"text":"Kamaliya, B.; Kumar, M.V.; Yelamaggad, C.V.; Prasad, S.K. Enhancement of electrical conductivity of a liquid crystal-gold","rect":[57.48833084106445,740.0763549804688,559.0175164587884,731.0298461914063]},{"page":12,"text":"nanoparticle composite by a gel network of aerosil particles. Appl. Phys. Lett. 2015, 106, 083110. [CrossRef]","rect":[57.48833084106445,751.5711669921875,476.9619351437839,742.4798583984375]},{"page":12,"text":"Kılıç, M.; Özdemir, Z.G.; Canli, N.Y.; Bulgurcuog˘lu, A.E.; Köysal, O.; Yılmaz, Ö.; Okutan, M. The impact of NiPc additive and","rect":[57.48833084106445,763.0660400390625,559.0150384746205,752.7655639648438]},{"page":12,"text":"laser light dielectric properties of E63 nematic liquid crystal. Ferroelectrics 2016, 505, 102–113. [CrossRef]","rect":[57.48833084106445,774.5608520507813,466.9418240597995,765.4695434570313]},{"page":13,"text":"Molecules 2021, 26, 2873","rect":[35.983306884765628,60.788047790527347,118.22841132503551,53.726043701171878]},{"page":13,"text":"13 of 13","rect":[532.09814453125,59.71322250366211,559.0166498504261,53.76585006713867]},{"page":13,"text":"36.","rect":[35.983306884765628,105.51161193847656,47.1861095208866,99.17011260986328]},{"page":13,"text":"37.","rect":[35.983306884765628,128.50135803222657,47.1861095208866,122.15985870361328]},{"page":13,"text":"38.","rect":[35.98329544067383,151.49000549316407,47.186098076794809,145.14849853515626]},{"page":13,"text":"39.","rect":[35.98331069946289,174.47975158691407,47.18611333558387,168.13824462890626]},{"page":13,"text":"40.","rect":[35.983306884765628,197.4694366455078,47.1861095208866,191.08316040039063]},{"page":13,"text":"41.","rect":[35.983306884765628,220.30679321289063,47.1861095208866,214.07278442382813]},{"page":13,"text":"42.","rect":[35.983306884765628,243.29550170898438,47.1861095208866,237.06149291992188]},{"page":13,"text":"43.","rect":[35.983306884765628,266.4374694824219,47.1861095208866,260.0511779785156]},{"page":13,"text":"44.","rect":[35.983306884765628,289.2747497558594,47.1861095208866,283.0407409667969]},{"page":13,"text":"45.","rect":[35.983306884765628,312.4167785644531,47.1861095208866,306.0304870605469]},{"page":13,"text":"46.","rect":[35.983306884765628,335.4054870605469,47.1861095208866,329.0191955566406]},{"page":13,"text":"47.","rect":[35.983306884765628,358.2427978515625,47.1861095208866,352.0087890625]},{"page":13,"text":"Patari, S.; Nath, A. Frequency Tuned Dielectric and Electrical Properties of a Thermotropic Liquid Crystal Compound 9OBA.","rect":[57.48833084106445,107.86727905273438,560.5806598484967,98.82079315185547]},{"page":13,"text":"Mater. Today: Proc. 2018, 5, 2105–2111. [CrossRef]","rect":[57.48833084106445,119.29945373535156,250.2836514523776,110.27088165283203]},{"page":13,"text":"Macdonald, J.R.; Cook, G.B. Reply to comments by almond and west on Na b-alumina immittance data analysis. J. Electroanal.","rect":[57.48833084106445,130.85702514648438,560.1345915711527,121.76575469970703]},{"page":13,"text":"Chem. Interfacial Electrochem. 1985, 193, 57–74. [CrossRef]","rect":[57.192466735839847,142.28810119628907,280.5837613156589,133.259521484375]},{"page":13,"text":"Porzi, G.; Concilio, C. Halogen—metal interconversion in 2,7-dibromonaphthalene and 2,7-dibromoanthracene. J. Organomet.","rect":[57.48833084106445,153.84567260742188,560.1339788026255,144.8170928955078]},{"page":13,"text":"Chem. 1977, 128, 95–98. [CrossRef]","rect":[57.192466735839847,164.4538116455078,192.34271822483854,156.249267578125]},{"page":13,"text":"Moynihan, C.T. Analysis of electrical relaxation in ionically conducting glasses and melts. J. Non-Crystalline Solids 1996, 203,","rect":[57.48833084106445,176.83541870117188,560.1365680516217,167.744140625]},{"page":13,"text":"359–363. [CrossRef]","rect":[57.48833084106445,187.44349670410157,135.33435640843229,179.2837371826172]},{"page":13,"text":"Cole, K.S.; Cole, R.H. Dispersion and Absorption in Dielectrics II. Direct Current Characteristics. J. Chem. Phys. 1942, 10, 98–105.","rect":[57.48833084106445,199.80712890625,560.5863345605068,190.7337646484375]},{"page":13,"text":"[CrossRef]","rect":[57.48833084106445,210.4331817626953,98.94766054661588,202.27342224121095]},{"page":13,"text":"Havriliak, S.; Negami, S. A complex plane representation of dielectric and mechanical relaxation processes in some polymers.","rect":[57.48833084106445,222.81472778320313,560.586694187893,213.7682342529297]},{"page":13,"text":"Polym. 1967, 8, 161–210. [CrossRef]","rect":[57.2104606628418,234.24586486816407,194.84296236546354,225.21728515625]},{"page":13,"text":"Dyre, J.C. The random free-energy barrier model for ac conduction in disordered solids. J. Appl. Phys. 1988, 64, 2456–2468.","rect":[57.48833084106445,245.80343627929688,560.5838336766217,236.712158203125]},{"page":13,"text":"[CrossRef]","rect":[57.48833084106445,256.4115295410156,98.94766054661588,248.2517547607422]},{"page":13,"text":"Binet, C.; Allart, A.; Judeinstein, P.; Roussel, F. Anisotropic charge transport in ion-conductive photoresponsive polyethylene","rect":[57.48833084106445,268.7931213378906,559.0175052072196,259.7645568847656]},{"page":13,"text":"oxide–based mesomorphic materials. Phys. Rev. E 2017, 95, 012708. [CrossRef] [PubMed]","rect":[57.48833084106445,280.26995849609377,408.0265713742526,271.19659423828127]},{"page":13,"text":"Barsoukov, E.; Macdonald, J.R. Impedance Spectroscopy: Theory, Experiment, and Applications, 2nd ed.; Wiley-Interscience: Hoboken,","rect":[57.48833084106445,291.7826843261719,560.1387147652913,282.69140625]},{"page":13,"text":"NJ, USA, 2005.","rect":[57.48833084106445,302.5341491699219,115.6980952996952,294.4012451171875]},{"page":13,"text":"Maschke, U.; Moundoungou, I.; Fossi-Tabieguia, G.J. Method for Extracting the Liquid Crystals Contained in an Element that","rect":[57.48833084106445,314.7724304199219,559.0206995976713,305.7259521484375]},{"page":13,"text":"Comprises a First Support And A Second Support-Associated Device. Patent No. EP3111276 (A1), 1 April 2017.","rect":[57.48833084106445,326.2493896484375,497.901662804578,317.2387390136719]},{"page":13,"text":"Perkowski, P. How to determine parameters of soft mode from dielectric spectroscopy performed using cells with ITO electrodes?","rect":[57.48833084106445,337.7611083984375,559.8140185928148,328.7146301269531]},{"page":13,"text":"Opto-Electronics Rev. 2011, 19, 76–82. [CrossRef]","rect":[57.139495849609378,349.1932373046875,243.98276339085417,340.1646423339844]},{"page":13,"text":"Belyaev, B.A.; Drokin, N.A.; Maslennikov, A.N. Impedance spectroscopy investigation of liquid crystals doped with ionic","rect":[57.48833084106445,360.750732421875,559.0175604846801,351.7042541503906]},{"page":13,"text":"surfactants. Phys. Solid State 2014, 56, 1455–1462. [CrossRef]","rect":[57.48833084106445,372.1828918457031,292.9608365109714,363.154296875]}]}