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Influence of electron donor‐acceptor interaction on the liquid crystallinity of copolymers derived from malonates with a mesogenic group using oligo(ethylene glycol) as a main chain spacer
Author(s) -
Kodaira Toshiyuki,
Kurachi Masato,
Chiou JinnYuan,
Endo Mitsuhiko
Publication year - 1999
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19990501)200:5<997::aid-macp997>3.0.co;2-q
Subject(s) - mesogen , copolymer , polymer chemistry , mesophase , ethylene glycol , materials science , acceptor , monomer , crystallography , electron acceptor , chemistry , phase (matter) , polymer , organic chemistry , liquid crystalline , physics , condensed matter physics , composite material
Copolymerization between two malonic acid esters with a mesogenic group ( 1 ) was carried out using oligo(ethylene glycol) as a flexible main chain spacer to see the effect of electron‐donor acceptor interactions between the mesogens on the phase transition behavior of the copolymers. The following four mesogenic groups were employed: 4‐(2‐phenylethoxy)‐4′‐biphenoxy ( 1 a ), p ‐nitrophenylazophenoxy ( 1 b ), 4‐(4′‐nitrophenylvinylene)phenoxy ( 1 c ), and p ‐methoxybiphenoxy group ( 1 d ). Monomers 1 a and 1 d have a mesogen with an electron‐donating group, while 1 b and 1 c have an electron‐withdrawing group. The copolymers of 1 a with 1 b display a mesophase over a much wider temperature range than the respective homopolymers of the pair. The copolymers derived from the pairs, 1 a – 1 c and 1 c – 1 d , have a tendency to show a crystalline phase with convex curves for the dependence of the transition to the isotropic state on copolymer composition. These results were explained by taking into consideration the electron‐donor acceptor interaction between their mesogens. The different thermal behavior was interpreted by assuming a stronger tendency for the formation of a molecular complex in the latter two. Only linear changes of transition temperatures between those of the respective homopolymer were observed for the copolymers derived from 1 a and 1 d .