摘要
以丙烯酸-2-乙基己酯(EHA)、二甲基丙烯酸乙二酯(EDMA)/季戊四醇四丙烯酸酯(PETTA)为混合单体、液晶P0616A为液晶相、Irgacure 184为光引发剂,通过UV光引发制备了聚合物分散液晶(PDLCs),研究了不同烷基链长醇,即乙醇(EtOH)、正丁醇(nBA)、正己醇(nHA)、正辛醇(nOA)和正十四醇(nTA)对体系光聚合动力学及其PDLCs液晶相变温度及电光特性的影响.结果表明引入醇分子显著加快了丙烯酸酯/液晶复合体系的光聚合反应速率,提高了单体的最终转化率,其中以正丁醇体系最为明显.随着醇分子烷基链的增长,体系的转化率趋于降低,但依然明显高于不含醇的体系.醇分子的加入降低了PDLCs中液晶相的TNI,且随着醇分子烷基链长的增长,PDLCs液晶相的TNI总体上呈降低的趋势.醇分子的加入增加了PDLCs液晶微区中向列相液晶的含量,而含正丁醇和正十四醇的体系液晶微区中向列相液晶低于其它3个含醇体系.醇分子的加入明显降低了PDLCs的阈值电压和饱和电压以及对比度.结合体系的光聚合速率和单体转化率,正丁醇是改善PDLCs性能的最佳选择.
Polymer dispersed liquid crystals （PDLCs） were prepared by UV photopolymerization of the mixture monomers of 2-ethylhexyl acrylate （EHA）, ethylene dimetbacrylate （EDMA） and pentaerythritol tetraacrylate （PETTA） in the presence of liquid crystals P0616A and photoinitiator Irgacure 184. The effects of different alcohols with different short chains, i. e. , ethanol （EtOH） , n-butanol （nBA） , n-hexanol （nHA） , n- octanol （nOA） and n-tetradecanol （nTA） , on the photopolymerization kinetics, liquid crystal phase transition temperature （TNj） and electro-optical performance of PDLCs were investigated. The results reveal that the addition of these non-reactive low molecular alcohols, especially nBA, significantly increases the polymerization rate and monomer conversion of monomer/liquid crystal dispersions, and the monomer conversion reduces with increasing the chain length of the alcohol, but remains higher than that without alcohol. Additionally, TN^of PDLCs decreases with adding alcohols, and tends to further decrease with the increasing of alcohol chain length. The addition of alcohols also increases the fraction of nematic phases in PDLCs, and the fractions of nematic phases in PDLCs containing nBA and nTA are lower than those containing EtOH, nHA and nOA. Finally,the alcohols dramatically decrease the threshold voltage, saturated voltage and contrast ratio of PDLCs. Combining the effect on the pbotopolymerization kinetics,nBA is the best choice for improving the performance of PDLCs.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2012年第1期41-46,共6页
Acta Polymerica Sinica
基金
国家自然科学杰出青年基金(基金号50825301)资助项目
关键词
聚合物分散液晶
醇
光聚合动力学
相行为
电光特性
Polymer dispersed liquid crystals, Alcohol, Photopolymerization kinetics, Phase transition,Electro-optical performance
