Synthesis and Properties of Side-Chain Liquid Crystalline Polyoxacyclopentanes

• Main Authors: Huang,Wen-Yao, 黃文堯
• Other Authors: Liaw,Ben-Ruey
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/26820940626473682308

碩士 === 國立臺灣科技大學 === 化學工程研究所 === 83 === The cationic ring-opening polymerization of 3,4-bis{[n-(4'-R-4- biphenyloxy)alkyloxy]ethyl}oxacyclopentane(R=BuO,CN or NO2,- n=3 ~10) with trimethylsilyl trifluoromethanesulfonate(TMSOTf) as initiator and propylene oxide as promotor to give novel side- chain liquid crystalline polymers with a poly(ether) main chain was investigated.In this study,we also found that TMSOTf without promotors did not initiate the ring opening polymerization of oxacyclopentane monomers even for several days at room temperature.To our suprise,when the reation was carried at higher temperature(≧40℃),it proceeded via an intramolecular cyclization to give di[6-(4'-R-4-biphenyloxy) hexyl]ether instead of poly(ether). Structures of the monomers and polymers were determined by IR, 1H NMR,13C NMR spectra and their mesomorphic behaviors were identified by differential scanning calorimetry (DSC) and polarized optical microscopy (POM).Polymers PBuO-n with an butoxy tail showed smectic mesophase except those with an spacer length n=3,while polymers PN-n with an nitro- tail exhibited enantiotropic nematic mesophase with n=5,7,8,9,and an unidentified phase with n=4,6,10. Nevertheless, PN-3 was amorphous. In the case of polymers PCN-n with a cyano- tail, they displayed nematic phase with n=4~8 and in contrast to the enantiotropic smectic phase with n=9,10. That is to say, By increasing the spacer length from n=8 to n=9, the homologues of polymers PCN-n showed enantiotropic smectic phase instead of nematic phase. Isotropization temperatures (Ti) alternated in an odd-even manner with spacer length (n) for the homologous series of polymers PN-n and PCN-n . Polymers PCN-n pressented odd-even effect up to spacer length of n=10 and When the spacer length n=9,10 showed enantiotropic semectic phase.