Study On Synthesis And Properties Of Liquid Crystalline Polyurethanes Containing Azobenzene Mesogenic Units

It's required very high in materials' function in our modern society.Polpothanes with many special perfOrmances play an imPOrtant role in kinds offields. Research of Liquid Crystalline Polyurethanes (LCPU) and Nonlinear Optical(NLO) PolyUrethanes attracts many scholars recently.The portion-oriented circumstance in LCPU casused by molecular ariangementProvides a better nonsymxnetrical environxneni for NLO Polgurethans. It also hasstronger hydrogen bond which can result in partly physical crosslinkage in polymers,Which can fasten orienting of chromophore. All these benefit to obtain high NLOcoefficient.In chaPter one, some basic concePtions about LC and the advance in LCPU aredescribed, esPecially the Synthesis methods on LCPU and the influence factors ofLCPU formation liquid crystalline phase. It is a1so referred to the NLO liquid crystalPOlyUrthanes and the system of NLO liquid crysta1 polymer briefly. Fchrmore, thepossibility of combining the NLO PolyUrthanes and LCPU is also discussed based onazobenzene comPoUnd, whch own liquid crysta1line mesogenic unit and nonlinearoPical wht togetheLA series of polyUrethanes with two kinds of diisocyanates were synthsized withazobenzene compoUnds which we prepared beforehand. The azobenzene compoundswere charaterized and confirmed by FTIR, 'H-NMR, UV-Vs, DSC, and elemenianalysis. Side chain polyurethanes with azo grouP are characterized and confirmed byFTIR, UV-Vis, DSC,VPO, Z-scan, polarize microscope. The results show that theend-grOup and the flexibility of main chain affects the growing uP of liquid crystallinephase greatly. Because the determinable way of detection is defective, it was notfounded the liquid crystalline behavior obviously contributes to the non1inear opticalthection.