Kumar Sunil, Hong Hyeryeon, Choi Woosuk, Akhtar Imtisal, Rehman Malik Abdul, Seo Yongho
Graphene Research Institute and HMC, Sejong University Seoul 05006 South Korea
Department of Nanotechnology and Advanced Materials Engineering, Sejong University Seoul 05006 South Korea.
RSC Adv. 2019 Apr 24;9(22):12645-12655. doi: 10.1039/c9ra00729f. eCollection 2019 Apr 17.
We have studied liquid crystals (LCs) and acrylate-assisted thiol-ene compositions to synthesize dye based colorful polymer dispersed liquid crystals (PDLCs) without using a photo-initiator for smart-windows applications. A typical PDLC mixture was prepared by mixing LCs with UV-curable monomers, which included triethylene glycol diacrylate (TEGDA), trimethylolpropane diallyl ether (TMPDE, di-functional ene monomer), trimethylolpropane tris(3-mercaptopropionate) (TMPTMP, a thiol as a cross-linker), and a dichroic dye. The ratios of the TMPDE/TMPTMP and the LCs/TEGDA showed significant effects in altering the properties of the UV-cured PDLCs. During the curing process, the monomers polymerize and led to the encapsulation of the LCs in the form of interesting fractal nanostructures by a polymerization induced phase separation process. The switching time, electro-optical properties, power consumption, and ageing of the fabricated PDLCs were investigated. It was possible to achieve a 70-80% contrast (Δ) at a voltage difference of ∼70 V with a fast switching time () as low as < 20 milliseconds (ms) and low power consumption. These PDLCs had a low threshold voltage that ranged between 10 and 20 V. The sustainability of the fabricated UV-cured PDLCs was analyzed for up to 90 days, and the PDLCs were observed to be stable.
我们研究了液晶（LCs）和丙烯酸酯辅助的硫醇-烯组合物，以合成用于智能窗户应用的基于染料的彩色聚合物分散液晶（PDLCs），且不使用光引发剂。通过将液晶与可紫外光固化的单体混合制备典型的PDLC混合物，这些单体包括三甘醇二丙烯酸酯（TEGDA）、三羟甲基丙烷二烯丙基醚（TMPDE，双官能烯单体）、三羟甲基丙烷三（3-巯基丙酸酯）（TMPTMP，用作交联剂的硫醇）和一种二向色性染料。TMPDE/TMPTMP的比例以及液晶/TEGDA的比例对改变紫外光固化的PDLCs的性能有显著影响。在固化过程中，单体发生聚合，并通过聚合诱导相分离过程以有趣的分形纳米结构形式包裹液晶。对制备的PDLCs的开关时间、电光性能、功耗和老化进行了研究。在约70 V的电压差下，有可能实现70 - 80%的对比度（Δ），开关时间（）低至< 20毫秒（ms）且功耗低。这些PDLCs的阈值电压较低，范围在10至20 V之间。对制备的紫外光固化PDLCs的可持续性进行了长达90天的分析，观察到PDLCs是稳定的。
