关键词: 甲壳型液晶高分子, Suzuki偶合反应, Wittig反应, 4, 4&prime, -二烷氧基-2&prime, -甲基-对-三联苯, 2, 5-二(4&prime, -烷氧基苯基)苯乙烯

Abstract: This paper describes the synthesis and free radical polymerization of 2,5-bis(4′-alkyloxyphenyl)styrene(M-n) for mesogen jacketed liquid crystal polymers(MJLCPs), where p terphenyl subsituted by alkoxy groups at both ends was used as mesogenic unit. Because of the absence of the polar linkage groups, such as —COO— or —CONH— as employed in the previous reported MJLCPs, Mn is believed to be polymerized easily by both free radical polymerization and ionic polymerization. The chemical structure of Mn was proved by ¹H NMR, mass spectrometry and elementary analysis. Their phase transition and liquid crystallinity were characterized by DSCand POM. Although M-1, M-2, M-3 and M-4 exhibited monotropic nematic mesophase, M-5 displayed enantiotropic nematic mesophase presumably because of its decreased melting transition temperature. All monomers were easily polymerized to moderately high molecular weight polymers. At elevated temperature above T_g, poly[2,5-bis(4′-alkoxyphenyl)styrene] showed a very stable mesophase. The formed birefrigence did noTdisappear until thermal decomposition started. Compared to other MJLCPs, the polymers reported here have much higher thermal stability.

Key words: Mesogen-jacketed liquid crystal polymer(MJLCP), Suzuki coupling reaction, Wittig reaction, 4,4′-Dialkoxy-2′-methyl-p-terphenyl, 2,5-Bis(4′-alkoxyphenyl)styrene