Author/Authors :
Tokita، نويسنده , , Masatoshi and Shikinaka، نويسنده , , Kazuhiro and Hoshino، نويسنده , , Teruki and Fujii، نويسنده , , Kyohei and Mikami، نويسنده , , Jun and Koshimizu، نويسنده , , Noboru and Sakajiri، نويسنده , , Koichi and Kang، نويسنده , , Sungmin and Watanabe، نويسنده , , Junji and Shigehara، نويسنده , , Kiyotaka، نويسنده ,
Abstract :
A series of syndiotactic polymethylenes having an alkyloxycarbonyl side chain, with the alkyl carbon numbers 2, 6, 12, and 18 at every main-chain carbon atom, was synthesized by rhodium complex-catalyzed stereo-selective polymerization. Differential scanning calorimetry (DSC) and X-ray diffraction revealed that all polymers formed thermotropic liquid crystalline phases. The polymethylene having an ethoxycarbonyl side chain formed a nematic phase whereas those having hexyloxy-, dodecyloxy-, and octadecyloxy-carbonyl side chains formed hexagonal columnar phases. The tendency of these polymers to form liquid crystalline phases is due to the rod-like helical conformation in the polymer backbone, which is estimated to be seven units per two turns (7/2) with a unit height of 1.054 إ along the helix axis.
