A mesogen-jacketed liquid crystal polymer

poly{2

5-bis [(4′-hexyloxyphenyl) oxycarbonyl] styrene} (PHPCS)

with number-averaged molecular weight of 1.28×105 and polydispersity of 1.48 was prepared via 2

2

6

6-tetramethyl-piperidinyloxy mediated free radical polymerization．The thermotropic behavior was studied by a combination of differential scanning calorimetry

thermogravimetry

polarized optical microscope and wide-angle X-ray diffraction．PHPCS was not crystalline over the entire temperature region studied．On heating

PHPCS first became an isotropic melt at glass transition temperature (Tg) and then a mesophase at temperatures much higher than Tg．On subsequent cooling

the formed ordered phase disappeared above Tg．Contrary to theoretical predictions and previous experimental observations

the transition from isotropic melt to liquid crystalline phase was an endothermic process and the order-disorder transition took place with concurrence of heat release．