大分子引发剂分子量对接枝聚合物基体的PDLC电光性能的影响

以可逆加成-断裂链转移(RAFT)、引发转移终止(iniferter)活性自由基聚合相结合的方法,用一步法制备了不同分子量的大分子引发剂RAFT-PS-co-PCMSI(MI),并通过紫外光聚合诱导相分离法制备了以接枝聚合物为基体的聚合物分散液晶(PDLC)膜.研究了不同分子量的MI对PDLC的微观形貌,关闭状态透光率,阈值电压,饱和电压以及记忆效应等方面的影响.研究表明,降低PDLC中MI的分子量,会使得液晶微滴粒径增大,阈值电压(Vth)、饱和电压(Vsat)减小,记忆效应、关闭状态透光率升高.

EFFECT OF MOLECULAR WEIGHT OF MACRO-INITIATOR ON ELECTRO-OPTICAL PROPERTIES OF POLYMER DISPERSED LIQUID CRYSTAL BASED ON GRAFT POLYMERS

Polymer dispersed liquid crystal(PDLC) films were prepared by photopolymerization induced phase separation(PIPS) with living macro-initiator(MI) of different molecular weights,synthesized by RAFT and iniferter polymerization.The effect of molecular weight of MIs on electro-optical properties of PDLC based on graft polymers was investigated.The effects of molecular weight of MIs on morphologies,transmittance,switching voltage and memory effect of PDLC films were studied in detail.It was found that the decrease in the molecular weight of MIs in the films led to the formation of larger liquid crystal droplets.The threshold voltage decreased from 15.9 V to 4.2 V and the off-state transmittance showed an increase tendency,which could be contributed to the increase of liquid crystal droplet diameter.In addition,the saturation voltage also decreased from 36.5 V to 16.4 V while the memory effect increased because of the decreased interface anchoring strength induced by the lower molecular weight of polymer matrix and weaker entanglement that polymer flexible main chain exerted on liquid crystal molecules.Therefore,the decrease decrease of molecular weight of MIs successfully improved the electro-optical properties of PDLC films based on graft polymers.