聚甲基丙烯酸-对-甲氧基偶氮苯烷氧基酯的合成及柔性间隔基对液晶行为的影响

通过甲基丙烯酸钾盐与溴化物的反应合成了一系列柔性间隔基长度不同的甲基丙烯酸 对 甲氧基偶氮苯烷氧基酯（ＰＭＡＡＺＯｎ，ｎ＝２，３，４，５，６），然后聚合成相应的聚合物．用１Ｈ ＮＭＲ和ＩＲ表征了聚合物的结构，ＧＰＣ测定了分子量，ＤＳＣ和偏光显微镜观测了液晶高分子的相行为和织构．研究了间隔基长度对织构、相变和热力学性质的影响，观测到聚合物的ＴＮＩ随间隔基的长度变化表现出的奇偶效应．

SYNTHESIS OF SIDE CHAIN LIQUID CRYSTALLINE POLYMETHACRYLATES CONTAINING AZOBENZENE MESOGENIC GROUPS AND THE EFFECT OF SPACER LENGTH ON THEIR LIQUID CRYSTALLINE BEHAVIORS

A series of thermotropic side chain liquid crystalline poly ω (4' methoxy 4 azophenyloxy)alkanoyl methacrylates (PMAAZO n,n =2,3,4,5,6) were prepared by the reaction of potassium methacrylate and 4 methoxy 4' (1 bromoalkoxy)azobenzene,then free radical polymerization in THF solution.Their structures were verified by 1H, 13 C NMR and IR spectra.The number average molecular weight ( M W) of PMAAZO n were around 20,000,thus the effects of M W on the liquid crystalline (LC) properties were negligible.The LC behaviors of the polymers obtained were examined by DSC and optical polarizing microscope.Only one nematic state for PMAAZO n,(n =2,3 and 4),and two LC states:one smectic and one nematic state for the polymers of n =5 and 6 were observed.As spacer length increased,glass transition temperature decreased.On the curves of Δ H and Δ S against spacer length,the lowest values appeared at n =3.The lowest stability of LC state was probably the result of odd even effect and low decoupling.The odd even effect on T NI of PMAAZO n was observed,and explained based on the placement of the mesogenic groups on relation to the polymer backbone.The physical aging process of the polymers would increase their T NI and decrease Δ H NI .