Premium
Copolymerization in Liquid Crystalline Media
Author(s) -
Hardy G.,
Cser F.,
Nyitrai K.
Publication year - 1979
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.197900034
Subject(s) - copolymer , mesogen , chemistry , monomer , comonomer , crystallography , reactivity (psychology) , liquid crystal , mesophase , polymer chemistry , phase diagram , phase (matter) , liquid crystalline , organic chemistry , polymer , materials science , medicine , alternative medicine , optoelectronics , pathology
The data at our disposal on the copolymerization of potentially mesogenic monomers either in mesomorphic or in isotropic phases are reviewed. There are only very few convincing data concerning the effect of the mesophase on the ratio of kinetic constants of the monomer ( r i = k ij / k ij ). The p ‐ethoxy‐ p '‐acryloyloxy‐azobenzene (EOA) and cholesteryl acrylate (CA) gave different r values in cholesteric and in isotropic state copolymerizations ( r CA,i = 0.28, r EOA,i = 0.57, r CA,m = 0.16, r EOA,m = 1.10). r values were determined in other systems consisting of p ‐methyl‐ p '‐acryloyloxyazoxybenzene (MAAB), phenyl‐ p ‐acryloyloxybenzoate (PAB), N‐acryloylpiperidine (AP), cholesterylvinylsuccinate (CUS) and cholesterylsuccinyl‐diglycoylacrylate (CSDA) as well as CA. ( r CA = 0.58, r PAB = 0.62, r CA = 0.16; r AP = 1.14; r PAB = 0.16; r AP = 0.81; r CVS = 0.01, r PAB = 2.36, r CSDA = 0.20, r PAB = 1.26, r MAAB = 2.40; r CVS = 0.02). These data were obtained in isotropic phase reactions and they do not satisfy the generally accepted concepts of reactivity. The structure of the copolymers were invesitgated by X‐ray diffraction and by thermal treatment. The copolymer/comonomer state diagram for the MAAB/CVS system were also used to determine the structural features of this system. Copolymers consisting of potentially mesogenic vinyl‐monomers are macromolecules with anisotropic properties. Their transition temperatures ( T g , T f , T a→i ) have minimal values at a given composition. The copolymers show different X‐ray Bragg periods before and after this composition. They can be regarded as anisotropic two phase systems, although they are not block copolymers. The data published in recent literature together with those obtained in our current work suggest that both the chemical and the physical structures of the copolymers built up from potentially mesogenic vinyl‐monomers are more dependent on topochemical than on pure chemical conditions.