Mesogen-Jacketed liquid crystalline polymers were synthesized in various chiral conditions using 1) (\|)\|menthol as a reaction solvent (additive),2) (\|)\|dimenthyl peroxydicarbonate as a chiral free radical initiator,3) menthyl methacrylate as a comonomer for copolymerization,4) (-)-sparteine-fluorenyllithium as a chiral anionic initiator and 5) a chiral monomer.In the polymerization using a chiral initiator or a chiral solvent,the helix-sense-selection was not found.In the case of the copolymerization,the chiral monomeric unit incorporated into the polymer chain was found to induce liquid crystallinity.Chiral mesogen-Jacketed polymer was also synthesized from chiral monomer 5.However,this polymer did not form a liquid crystal phase although it met the model of Mesogen-Jacketed liquid crystalline polymers.
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]
