Fully aromatic thermotropic liquid crystalline polyesters of 3,4′‐dihydroxybenzophenone

Abstract

SYNOPSISA series of fully aromatic, thermotropic polyesters, derived from 3,4'-dihydroxybenzophenone and various aromatic dicarboxylic acids, was prepared by the high-temperature solution polycondensation method and examined for thermotropic behavior by a variety of experimental techniques. The aromatic dicarboxylic acids used in this study were 2,6-naphthalenedicarboxylic acid, 4,4'-hibenzoic acid, and terephthalic acid.The two homopolymers of 3,4'-DHB with either 2,6-NDA or 4,4'-BBA formed nematic LC phases a t 285°C and 255°C and also exhibited isotropization transitions (Ti ) at 317°Cand 339"C, respectively. The copolymer of 3,4'-DHB with 50% TA and 50% 2,6-NDA also formed a nematic LC phase and had a broader range of LC phase than that of its respective homopolymers. Two other copolymers of 3,4'-DHB, both containing 50% 4,4'-BBA, also formed nematic LC phases a t low T, values. All of the thermotropic polyesters had high thermal stabilities.

Synthesis, characterization, and thermal properties of phosphorus‐containing, wholly aromatic thermotropic copolyesters

“…[7][8][9][10] A third way is to use monomers with nonlinear or kinked structures to lower the persistence length of the polymer chain and to reduce lateral interactions in the solid state. [11][12][13][14] In addition, the introduction of flexible spacers between rigid-rod mesogens also can be used to lower T m by reducing the aspect ratio of the polymer chain. [15][16][17] In this study, a series of wholly aromatic thermotropic copolyesters with relatively low thermal transition temperatures were investigated.…”

Main chain, thermotropic, liquid crystalline, hydrogen‐bonded polymers of 4,4′‐bipyridyl with 4,4′‐dicarboxy‐α,ω‐diphenoxyalkanes

“…POM studies suggested that the lowest temperature endotherm corresponded to the crystal-to-LC phase transition (T m ), which underwent an appreciable degree of supercooling, as expected [59]. The other two high temperature endotherms were presumably related to transitions of the high-order smectic to the low-order smectic phase.…”

Novel poly(aryl ether ketone)s exhibiting liquid crystallinity

“…The later was indicated by the decrease in heat of fusion (H m ) in Table 1 [6]. Compared to paralinked polymers, meta-linked polymers showed lower or no melting transition temperature.…”