室温显示胆甾相的侧链液晶聚合物的合成与表征

Synthesis and characterization of side chain liquid crystalline polymers displaying cholesteric phase at room temperature

将聚甲基含氢硅氧烷(PMHS)与向列相柔性单体11-(4’-(4-乙氧基苯甲酸)苯)十一烯酸酯(M1)和胆甾相单体烯丙氧基苯甲酸胆甾醇酯(M2)接枝共聚合成了聚合物P1~P7。利用红外光谱(FTIR)、氢谱(1H NMR)、差示扫描量热法(DSC)、偏光分析(POM)、X射线衍射分析(XRD)、热失重分析(TGA)、旋光分析等手段研究了单体和聚合物的结构和液晶性能。结果表明,除聚合物P7为向列型液晶聚合物外,P1~P6为胆甾型液晶聚合物,即向列相柔性单体M1的引入并未改变胆甾相,而且与柔软的硅氧烷主链共同作用起到了降低玻璃化温度(P5、P6在室温即出现液晶态)、拓宽液晶区间、稳定液晶相、降低成本的作用,有利于液晶聚合物的应用。

A series of liquid crystal(LC)polymers(P1~P7)were synthesized by grafting with nematic flexible monomer 4-(undec-10-enoyloxy)phenyl 4-ethoxybenzoate(M1)and cholesteric monomer cholesteryl allyloxybenzoate(M2)to polymethyl hydrosiloxane(PMHS).The chemical structures and properties of the monomers and copolymers were investigated by means of fourier transform infrared spectroscopy(FTIR),nuclear magnetic resonance hydrogen spectrometer(1HNMR),differential scanning calorimetry(DSC),polarised optical microscopy(POM),X-ray diffraction(XRD),thermogravimetric analysis(TGA)and polarimeter.The analyses show that P1~P6 are cholesteric LC polymers,except that P7 is a nematic LC polymer.The introduction of nematic flexible monomer M1 did not change the cholesteric phase.The introduction of M1 together with the soft siloxane main chain play a role in reducing the glass transition temperature(P5 and P6 show LC state at room temperature),widening the LC range,stabilizing the LC phase and reducing the cost,which is beneficial to the application of LC polymers.