Molecular engineering of liquid crystal polymers by living polymerization. II. Living cationic polymerization of 11‐[(4‐cyano‐4′‐biphenyl) oxy] undecanyl vinyl ether and the mesomorphic behavior of the resulting polymers

The synthesis and living cationic polymerization of 11‐[(4‐cyano‐4′‐biphenyl)oxy]‐undecanyl vinyl ether (6–11) are described. The mesomorphic phase behavior of poly(6–11) with different degrees of polymerization was compared to that of 6–11 and of 11‐[(4‐cyano‐4′‐biphenyl) oxy] undecanyl ethyl ether (8–11) which is the model compound of the monomeric structural unit of poly(6–11). 6–11 displays a monotropic SA and a monotropic nematic mesophase while 8–11 an enantiotropic SA mesophase. Poly(6–11) with low degrees of polymerization exhibits an enantiotropic SA mesophase. Poly(6–8) with high degrees of polymerization displays an enantiotropic SX (i. e., an unidentified smectic phase) and an enantiotropic SC mesophase. These results demonstrate that the transformation of the nematic mesophase of the monomer into a smectic mesophase after polymerization, occurs at the level of monomeric structural unit.