Design, Synthesis, and Characterization of a Combined Main-Chain/Side-Chain Liquid Crystalline Polymer Based on Mesogen-Jacketed Liquid Crystal Polymer via Atom Transfer Radical Polymerization

A novel combined main-chain/side-chain liquid crystalline polymer based on mesogen-jacketed liquid crystal polymers (MJLCPs) containing two biphenyls per mesogenic core of MJLCPs main chain, poly(2,5-bis{[6-(4-butoxy-4'-oxy-biphenyl)hexyl]oxycarbonyl} styrene) (P1-P8) was successfully synthesized via atom transfer radical polymerization (ATRP). The chemical structure of the monomer was confirmed by elemental analysis, H-1 NMR, and C-13 NMR. The molecular characterizations of the polymer with different molecular weights (P1-P8) were performed with H-1 NMR, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). Their phase transitions and liquid-crystalline behaviors of the polymers were investigated by differential scanning calorimetry (DSC) and polarized optical microscope (POM). We found that the polymers P1-P8 exhibited similar behavior with three different liquid crystalline phases upon heating to or cooling in addition to isotropic state, which should be related to the complex liquid crystal property of the side-chain and the main-chain. Moreover, the transition temperatures of liquid crystalline phases of P1-P8 are found to be dependent on the molecular weight. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7310-7320, 2008