Synthesis and characterization of four-armed star mesogen-jacketed liquid crystal polymer

The synthesis of four-armed star mesogen-jacketed liquid crystal polymer was achieved by atom transfer radical polymerization in chlorobenzene solution using pentaerythritol terakis(2-bromoisobutyrate) (PT-Br) as an initiator and CuBr/sparteine complex as a catalyst. The results show that the number average molecular weigh is creased linearly vs. monomer conversion, and that the polydispersities were quite narrow (<1.19), which is the character of controlled polymerization. The structure was experimentally confirmed by ¹H NMR. The liquid-crystalline behavior of the four-armed star polymer was studied using DSC and POM. Only the polymer with a M_n,GPC beyond 3.68×10⁴ g/mol formed a liquid crystalline phase which was quite stable with a high clearing point.