Crosslinked liquid crystalline polymers based on 4,4'-bis(n-(acryloyloxy)alkyloxy)biphenyl monomers

 
 
 
 

Crosslinked liquid crystalline polymers based on 4,4'-bis(n-(acryloyloxy)alkyloxy)biphenyl monomers

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Title: Crosslinked liquid crystalline polymers based on 4,4'-bis(n-(acryloyloxy)alkyloxy)biphenyl monomers
Author: Qian, Xuejun
Description: Two homologous series of potentially mesomorphic monomers, 4,4′-bis(n-(acryloyloxy)alkyloxy) biphenyl (BnA) and 2,6-bis(n-(acryloyloxy)alkyloxy) naphthyl (NnA) were synthesized. Researches in three different areas were conducted based on above monomers: i. The first three chapters concern about topochemically controlled polymerization of BnA in mesophases. Generally two liquid crystalline phases were observed for BnA homologues, S B and S E. All the BnA-S E phases assume a tilted bilayer structure and have well defined 3-dimensional (solid-like) structures. Long range order exists in the smectic layer normal direction as well as in the lateral direction. The third chapter describes the photopolymerization of monomer B5A. Polymers (PB5A's) with different liquid crystalline structures were obtained. When B5A was cured in the S E phase, a quasi-topochemical reaction was involved and the resulting polymer was also in a S E phase. Two smectic B phases (PB5A-S B α and β phases) with different molecular arrangements were obtained when B5A was cured in the S B phase. When B5A was cured in the isotropic state, only a nematic LC structure was obtained. The molecular organization within th e monomer dictates the resulting polymer structure. ii. The fourth chapter examines the spacer concept in side chain liquid crystal polymers. The mesophase formation is thought to be realized due to the decoupling of the motions of the isotropic backbone and the anisotropic mesogenic side chain by the use of a flexible spacer group. In this study, a detailed investigation of the effect of spacer length on the structural ordering of side-chain LC polymers was carried out based on two homologous series of polymeric systems, PBnA and PNnA. It was found that as n increases, the decoupling of motions between the backbone and side-chain mesogenic group increases, and consequently, the LC order within the polymeric system increases. iii. Finally, in the fifth chapter, an attempt was made to estimate the glass transition of polymethylene. We employed a group contribution approach to the problem, i.e. extrapolation of the transition temperature of two homologous series of polymers (PBnA and PNnA) with increasing methylene group content. The monomers were photopolymerized in the isotropic state so that amorphous polymethylene was obtained. (Abstract shortened by UMI.
Permanent Link: http://rave.ohiolink.edu/etdc/view?acc_num=case1056727146
http://hdl.handle.net/2374.OX/16101
Date: 1993

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