含非线性双酚结构的热致液晶聚芳酯的合成与性能

Synthesis and performance of thermotropic liquid crystalline polyarylates with nonlinear bisphenol structure

以对羟基苯甲酸(HBA)、对苯二甲酸(TA)、联苯二酚(BP)和2,6-萘二甲酸(NDA)为原料,采用一步熔融缩聚法合成兼具优异加工性和耐热性的热致液晶聚芳酯TLCP-BP。通过调控分子链结构,用非线性双酚单体4,4′-二羟基二苯砜(HDPSO)代替主链HBA/BP/TA/NDA中的线性双酚单体BP,从而合成TLCP-HDPSO。采用热重分析仪、差示扫描量热仪和动态热机械分析仪评价材料的热学性能,利用广角X射线衍射仪、热台偏振光学显微镜和流变仪分别研究TLCP的结晶度、液晶相和流变行为。结果表明:TLCP-BP具有高玻璃化转变温度(t g=270℃)、高热稳定性(质量损失5%时的温度t d,5%=507℃)、典型向列相液晶纹影织构(结晶相-向列相转变温度t K-N=350℃),以及具有TLCP纤维形貌的单相结构;TLCP-HDPSO表现出微弱的液晶相,但在介观尺度上不存在(微)相分离。非线性双酚单体的引入影响了分子链的规整度及链段分布,制得的TLCP共聚物形貌均相程度远远优于共混物。

A novel thermotropic liquid crystalline polyarylate(TLCP-BP)composed of p-hydroxybenzoic acid(HBA),terephthalic acid(TA),hydroquinone(BP)and 2,6-naphthalene dicarboxylic acid(NDA)with excellent processability and heat resistance was synthesized by one-step melt polycondensation.With rational design of regulatory molecular chain structure,TLCP-HDPSO was synthesized by replacing the linear bisphenol monomer BP in the main chain HBA/BP/TA/NDA with the nonlinear bisphenol monomer 4,4-dihydroxydiphenyl sulfone(HDPSO).The thermal properties of TLCP were characterized by thermogravimetric analyzer,differential scanning calorimeter and dynamic thermomechanical analyzer.The crystallinity,liquid crystal phase behavior and rheological behavior of TLCP were studied by wide-angle X-ray diffraction,hot stage polarization optical microscope and rheometer.The results show that TLCP-BP has a single-phase structure with high t g(270℃),high thermal stability t d,5%(507℃),typical nematic liquid crystal schlieren texture(t K-N=350℃)and typical TLCP fiber morphology.The TLCP-HDPSO shows weak liquid crystal phase and there is no phase separation on the mesoscopic scale.The introduction of nonlinear bisphenol monomer affects the regularity and segment distribution of molecular chain.The morphology of TLCP copolymer is much better than that of the blend.