含亚胺基热致性液晶聚氨酯的合成与表征

以对苯二酚二对苯甲酸酯(HQB)、N,N′-二(ω-羟乙基)苯均四甲酰二亚胺(BHDI)、甲苯二异氰酸酯(TDI)为单体,利用溶液缩聚方法,合成了含有亚胺基的三种液晶聚氨酯(HBLCP)。采用红外光谱(FT-IR)、差示扫描量热(DSC)、偏光显微镜(POM)、X射线衍射(WAXD)和热重分析(TGA)等手段对液晶聚氨酯进行表征。结果表明,该类液晶聚氨酯的熔点(Tm)和各向同性温度(Ti)随着HQB含量的增加而提高;POM观察表明,在液晶态温度区间170℃～190℃范围内显示液晶行为,并呈现向列相织构;其广角X射线衍射图在2θ角为15°～32°范围内有一组强度不等的衍射峰,所合成的液晶聚氨酯具有较高的热稳定性。

The Synthesis and Characterization of Liquid Crystal Polyurethane Containing Imide Units

Three kinds of liquid crystal polyurethanes(HBLCP) containing ester units and imide units were synthesized by polyaddition reaction of hydroquinone dibenzoate ester(HQB) with 2,4-toluenediisocyanate(2,4-TDI) and N,N′-bis(2-hydroxyhexyl) dicarboxyimide(BHDI) through changing the molar ratio of HQB and BHDI.HBLCPs were characterized by infrared spectroscopy(FT-IR),differential scanning calorimetry(DSC),polarized light microscopy(POM),X-ray diffraction(WAXD) and thermogravimetric analyse(TGA).The results show that the melting points(Tm) and isotropic temperatures(Ti) of HBLCP are improved with the content of HQB increasing.The analysis of POM indicates that all of the polyurethane polymers exhibit thermotropic nematic liquid crystalline textures between 170 ℃ and 190 ℃.WAXD results show the synthesized HBLCP displays a range of sharp peaks at 16°～32°,and all of the liquid crystal polyurethanes reveal relatively good thermal stability.