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 bot...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, M n is believed to be polymerized easily by both free radical polymerization and ionic polymerization. The chemical structure of M n was proved by 1H NMR, mass spectrometry and elementary analysis. Their phase transition and liquid crystallinity were characterized by DSC and 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 not disappear until thermal decomposition started. Compared to other MJLCPs, the polymers reported here have much higher thermal stability. [WT5HZ]展开更多
文摘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, M n is believed to be polymerized easily by both free radical polymerization and ionic polymerization. The chemical structure of M n was proved by 1H NMR, mass spectrometry and elementary analysis. Their phase transition and liquid crystallinity were characterized by DSC and 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 not disappear until thermal decomposition started. Compared to other MJLCPs, the polymers reported here have much higher thermal stability. [WT5HZ]
