Molecular Engineering Of Liquid Crystal Polymers By Living Polymerization英文电子书.pdf

Macromolecules 1991,24, 1017-1024 1017 Molecular Engineering of Liquid-Crystal Polymers by Living Polymerization. 3.t Influence of Molecular Weight on the Phase Transitions of Poly(8-[ (4-cyano-4’-biphenyl)oxy]octylvinyl ether) and of Poly(6-[ (4-cyano-4’-biphenyl)oxy]hexyl vinyl ether] V.Percec’ and M. Lee Department of Macromolecular Science, Case Western Reserve University, Cleveland, Ohio 44106 Received April 11, 1990;Revised Manuscript Received August 17, 1990 ABSTRACT: The synthesis and living cationic polymerization of 8-[(4-cyano-4’-biphenyl)oxy]octylvinyl ether (6-8) and of 64 (4-cyano-4’-biphenyl)oxy]hexylvinyl ether (6-6)are described. The mesomorphic behavior of poly(6-8) and poly(6-6) with different degrees of polymerization and narrow molecular weight distribution was compared to that of the 6-8 and 6-6 and of 8-[(4-cyano-4’-biphenyl)oxy]octylethyl ether (8-8)and 6-[(4- cyano-4’-biphenyl)oxy]hexylethyl ether (8-6). 8-8and 8-6are the model compounds of the monomeric structural units of poly(6-8) and poly(6-6). 6-8 displays an enantiotropic nematic mesophase, 6-6 and 8-6 exhibit a monotropic nematic mesophase, and 8-8gives a monotropic nematic and a monotropic SA mesophase. Poly- (6-8) with a degree of polymerization of 2.1 and poly(6-6)s with degrees of polymerization from 3.3 to 7.3 display an enantiotropic SA and an enantiotropic