环己烷类聚硅氧烷侧链液晶的合成与液晶行为研究

选用环己烷类液晶基元反式-4-乙烯基-反式-4’-丙基双环己烷(MA)和反式-4-丁烯基-反式-4’-丙基双环己烷(MB),通过硅氢加成反应将其接枝到柔性的聚硅氧烷主链上,合成了含有2种环己烷结构的聚硅氧烷侧链液晶P_(AB),产率为80.3%。采用傅立叶变换红外光谱法(FTIR)和氢核磁共振谱法(~1H-NMR)对其分子结构进行表征,说明其分子结构符合预期;采用热台偏光显微镜法(POM)和X射线衍射法(XRD)对其液晶相类型和液晶行为进行观察和分析,发现在升降温过程中所呈现出胆甾相油状条纹织构和小板块织构,揭示出因有序度不同所导致的不同织构特征;采用差示扫描量热法(DSC)和综合热分析法(TGA)对其热性能进行分析,确定其液晶区间为28.68K,T_(d(5wt%))为405.25℃,均高于液晶基元的液晶区间和热稳定性。

Synthesis and mesomorphic behavior of side-chain liquid-crystalline polysiloxanes containing two mesomorphic monomer with cyclohexane

A novel Side-Chain Liquid-Crystalline Polysiloxanes containing two Mesomorphic monomer with Cyclohexane (P_AB) was synthesized by graft polymerization, using (trans, trans)-4-propyl-4'-vinyl-bicyclohexane(M_A) and (trans, trans)-4-propyl-4'-butenyl-bicyclohexane(M_B)with Cyclohexane groups, and the production rate is 80.3%. The molecular structure of P_AB was confirmed by means of Fourier transform infrared spectroscopy and Hydrogen-nuclear magnetic resonance spectra. Liquid crystal phase and liquid crystal behavior of P_AB were analyzed by polarizing optical microscopy(POM) and X-ray diffraction(XRD), illustrating the cholesteric oily striated texture and platelet texture during increasing and decreasing temperature, and different texture character resulting from order of molecular chain. Thermal properties of P_AB were analyzed by differential scanning calorimetry(DSC) and thermal gravimetric analyzer (TGA), confirming the Mesomorphic region of 28.68 K and the 5% TG temperature(T_d(5wt%)) of 405.25 ℃, which are higer than that of M_A and M_B.