Mesogen-jacketed liquid crystalline polymers via stable free radical polymerization

Stable free-radical polymn. was used in the controlled synthesis of poly(2,5-bis[(4-butylbenzoyl)oxy]styrene), PBBOS. This mesogen-jacketed liq.-cryst. polymer, which has mesogenic units attached directly to the backbone in a side-on mode, was found to exhibit thermotropic liq. crystallinity similar to more conventional main-chain architectures. Stable free-radical polymn. of PBBOS consistently produced mol. wt. distributions below the theor. limiting polydispersity of 1.5 calcd. for a conventional free radical polymn. process. Surprisingly, a comparison of the synthesis of polystyrene to the polymn. of PBBOS under nearly identical conditions showed that the PBBOS polymd. with a significantly higher reaction rate and monomer conversion efficiency. The nematic phase of these polymers was detd. to be stable over the temp. range spanning the polymer glass transition temp. up to the temp. for thermal decompn. The mol. arrangement of the PBBOS polymers was examd. by wide-angle x-ray diffraction and is described here.