Thermotropic liquid crystals of polyesters having a mesogenic p,p'-bibenzoate unit. IV: Mesophase behavior of polyesters with branched spacers

• Published in: Polymer journal Vol. 24; no. 6; pp. 597 - 601
• Main Authors: WATANABE, J, HAYASHI, M, KINOSHITA, S, NIORI, T
• Format: Journal Article
• Language: English
• Published: Tokyo Society of Polymer Science 1992
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Structure, morphology and analysis; Arylate polymer; Biphenyl derivatives; Ester polymer; Thermotropic state; Property structure relationship; Smectic state; Mesomorphic state structure; Experimental study; Liquid crystals; Phase transitions
• ISSN: 0032-3896; 1349-0540
• DOI: 10.1295/polymj.24.597

In the first paper of this series, we reported the thermotropic mesophase properties of main-chain polyesters that can be constructed by an alternative arrangement of the p,p'-bibenzoate unit as a mesogenic group and alkanediol as a flexible spacer. The polyesters are designated BB-n where n is the number of methylene units in the diol. This homologous series of BB-n (n=3-9) invariably forms smectic mesophases whose isotropization temperatures and entropies exhibit an even-odd oscillation with the number of intervening methylene units, n. The even-odd oscillation can also be seen on the thickness of smectic layer. In this study, we prepared another homologous series of BB-n polyesters. The polyesters are analogous to the BB-4 polyester by having the butylene spacer, but different by containing branched methyl groups. The mesophase behavior of these polyesters was examined by DSC, optical microscopic and X-ray methods, and the effects of the branched methyl groups on the mesophase structure and properties are discussed in a comparison with the BB-4 polyester forming a S sub(A) phase.