Phase behaviour and structural characterization of poly(1,3-propylene adipate)s with cyanoazobenzene side groups
作者:
E. L. TASSI,
M. PACI,
P. L. MAGAGNINI,
B. YANG,
O. FRANCESCANGELI,
F. RUSTICHELLI,
期刊:
Liquid Crystals
(Taylor Available online 1998)
卷期:
Volume 24,
issue 3
页码: 457-465
ISSN:0267-8292
年代: 1998
DOI:10.1080/026782998207299
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The phase behaviour and the structure of three poly(1,3-propylene adipate)s containing cyanoazobenzene side groups bonded to the backbone unit through flexible spacers with 6, 8 and 10 methylene groups have been studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and X-ray diffraction (XRD) analysis. The polyadipates behave as enantiotropic side group liquid crystalline polymers. XRD analysis has shown that the organized phase of these polyadipates possesses a crystalline or a tilted structure of the SmF or SmG type. The temperature of fusion of this phase (Tm= 45-48 C) is almost independent of the length of the side group spacers. The crystalline phase can be obtained only by prolonged annealing at room temperature because crystallization from kinetically hindered. The range of thermodynamic stability (Ti- Tm) of the mesophase formed on melting increases with the length of the side group flexible spacers. The structure of the mesophase, determined by XRD, is of the smectic A type, and is characterized by a relatively large longitudinal displacement of the side groups, which is responsible for the unusually weak low angle Bragg reflections.
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