首先通过巯烯反应合成了八羧基笼形聚倍半硅氧烷(POSS-COOH),并利用核磁共振氢谱和傅里叶变换红外光谱证实了POSS-COOH的合成。以4-羟基苯甲酸(HBA)和6-羟基-2-萘甲酸(HNA)为原料,通过改变POSS-COOH的添加比例,采用“一锅法”熔融缩聚制备了一系列POSS核星型热致液晶聚合物(TLCP)。通过傅里叶变换红外光谱仪、特性黏度测试、差示扫描量热仪、热重分析仪、热台偏光显微镜对TLCP的结构与性能进行研究。结果表明:随着POSS-COOH比例的增大,TLCP的熔融温度和结晶温度逐渐下降,最大热失重温度升高;当POSS-COOH比例由0提高到0.1%(摩尔分数)时,TLCP的介电常数由3.48降低到3.08,介电损耗由2.2×10-3升高到6.9×10-3(测试频率107Hz);制备的POSS核星型TLCP具有良好的热稳定性和可调的介电性能,在电子通信领域具有潜在的应用价值。
In this research,polyhedral octacarboxylic silsesquioxane (POSS-COOH) was synthesized through thiol-ene reaction,and its successful preparation was confirmed by 1H nuclear magnetic resonance (1H-NMR) spectra and Fourier transform infrared spectroscopy (FT-IR).A series of star-shaped thermotropic liquid crystal polymers (TLCP) with POSS-cores were prepared via “one pot” melt polycondensation of 4-hydroxybenzoic acid (HBA),6-hydroxy-2-naphthoic acid (HNA) and POSS-COOH with varied ratios.The structures and properties of TLCP were studied by FT-IR,intrinsic viscosity,differential scanning calorimetry (DSC),thermogravimetric analysis (TGA),and hot stage polarizing microscope (POM).It was found that as the POSS-COOH ratio increased,the melting temperature and crystallization temperature of TLCP gradually decreased,while the maximum thermogravimetric temperature increased.When the POSS-COOH ratio increased from 0 to 0.1%,the dielectric constant of the TLCP decreased from 3.48 to 3.08,and the dielectric loss increased from 2.2×10-3 to 6.9×10-3(107Hz).Overall,star-shaped TLCP with POSS-cores exhibited excellent thermal stability and tunable dielectric properties,making it potentially valuable for applications in the field of electronic communication.
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