Synthesis and Characterization of Mesogen-Jacketed Liquid- Crystal Polymers Based on 2,5-Bis(4-alkoxyphenyl)styrene

Content Provider	Semantic Scholar
Author	Yu, Zhenning Tu, Hui-Lin Wan, Xinhua Chen, Xiaofang Zhou, Qi-Feng
Copyright Year	2003
Abstract	A series of novel mesogen-jacketed liquid-crystal polymers, poly(2,5-bis(4- alkoxyphenyl)-styrene) (P-n, n 1-11), were prepared via free-radical polymerization of newly synthesized monomers, 2,5-bis(4-alkoxyphenyl)styrene (M-n, n 1-11). The influence of the alkoxy tail length on the liquid-crystalline behaviors of the monomers and the polymers was investigated with differential scanning calorimetry (DSC), ther- mogravimetry, polarized optical microscopy (POM), and wide-angle X-ray diffraction (WAXD). The monomers with n 1- 4, 9, and 11 were monotropic nematic liquid crystals. All other monomers exhibited enantiotropic nematic properties. Their melting points (T m's) decreased first as n increased to 6, after which Tm increased slightly at longer spacer lengths. The isotropic-nematic transition temperatures decreased regu- larly with increasing n values in an odd- even way. The glass-transition temperatures (T g's) of the polymers first decreased as the tail lengths increased and then leveled off when n 7. All polymers were thermally stable and entered the mesophase at a temperature above T g. Upon further heating, no mesophase-to-isotropic melt transition was observed before the polymers decomposed. WAXD studies indicated that an irre- versible order- order transition for the polymers with short tails (n 5) and a reversible order- order transition for those with elongated tails (n 6) occurred at a temperature much higher than T g. However, such a transition could not be identified by POM and could be detected by DSC only on heating scans for the polymers with long tails (n 7).
Starting Page	1454
Ending Page	1464
Page Count	11
File Format	PDF HTM / HTML
DOI	10.1002/pola.10689
Volume Number	41
Alternate Webpage(s)	http://www.chem.pku.edu.cn/wanxh/pdf/03-01.pdf
Alternate Webpage(s)	https://doi.org/10.1002/pola.10689
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article