Kizhakidathazhath Rijeesh, Nishikawa Hiroya, Okumura Yasushi, Higuchi Hiroki, Kikuchi Hirotsugu
Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka 819-0395, Japan.
Polymers (Basel). 2020 Jul 22;12(8):1625. doi: 10.3390/polym12081625.
The widespread electro-optical applications of polymer dispersed liquid crystals (PDLCs) are hampered by their high-driving voltage. Attempts to fabricate PDLC devices with low driving voltage sacrifice other desirable features of PDLCs. There is thus a clear need to develop a method to reduce the driving voltage without diminishing other revolutionary features of PDLCs. Herein, we report a low-voltage driven PDLC system achieved through an elegantly simple and uniquely designed acrylate monomer (A3DA) featuring a benzene moiety with a dodecyl terminal chain. The PDLC films were fabricated by the photopolymerization of mono- and di-functional acrylate monomers (19.2 wt%) mixed in a nematic liquid crystal E7 (80 wt%). The PDLC film with A3DA exhibited an abrupt decline of driving voltage by 75% (0.55 V/μm) with a high contrast ratio (16.82) while maintaining other electro-optical properties almost the same as the reference cell. The response time was adjusted to satisfactory by tuning the monomer concentration while maintaining the voltage significantly low (3 ms for a voltage of 0.98 V/μm). Confocal laser scanning microscopy confirmed the polyhedral foam texture morphology with an average mesh size of approximately 2.6 μm, which is less in comparison with the mesh size of reference PDLC (3.4 μm), yet the A3DA-PDLC showed low switching voltage. Thus, the promoted electro-optical properties are believed to be originated from the unique polymer networks formed by A3DA and its weak anchoring behavior on LCs. The present system with such a huge reduction in driving voltage and enhanced electro-optical performance opens up an excellent way for abundant perspective applications of PDLCs.
聚合物分散液晶（PDLC）广泛的电光应用受到其高驱动电压的阻碍。试图制造具有低驱动电压的PDLC器件会牺牲PDLC的其他理想特性。因此，显然需要开发一种方法来降低驱动电压，同时又不削弱PDLC的其他革命性特性。在此，我们报道了一种通过一种设计优雅简单且独特的丙烯酸酯单体（A3DA）实现的低电压驱动PDLC系统，该单体具有一个带有十二烷基端链的苯部分。PDLC薄膜是通过将单官能和双官能丙烯酸酯单体（19.2 wt%）在向列型液晶E7（80 wt%）中混合进行光聚合制备的。含有A3DA的PDLC薄膜在保持其他电光性能与参考单元几乎相同的情况下，驱动电压急剧下降了75%（0.55 V/μm），同时具有高对比度（16.82）。通过调节单体浓度，响应时间被调整到令人满意的程度，同时保持电压显著较低（在电压为0.98 V/μm时为3 ms）。共聚焦激光扫描显微镜证实了多面体泡沫纹理形态，平均网眼尺寸约为2.6μm，与参考PDLC的网眼尺寸（3.4μm）相比更小，但A3DA - PDLC显示出低开关电压。因此，认为增强的电光性能源自A3DA形成的独特聚合物网络及其在液晶上的弱锚定行为。这种驱动电压大幅降低且电光性能增强的系统为PDLC丰富的潜在应用开辟了一条极佳的途径。
