화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.112, No.42, 13225-13230, 2008
Induced Smectic Phase in Mixtures of Hyperbranched Polyester and Liquid Crystal Mesogens
The phase diagram of a mixture consisting of hyperbranched polyester (HBPEAc-COOH) and eutectic nematic liquid crystals (E7) has been established experimentally by means of differential scanning calorimetry and polarized optical microscopy subjected to prolonged annealing. The observed phase diagram is an upper azeotrope, exhibiting the coexistence of nematic + isotropic phase in the vicinity of 90 similar to 110 degrees C above the clearing temperature of neat E7 (60 degrees C). With decreasing temperature, a focal-conic fan shaped texture develops in the composition range of 63 similar to 93 wt % of the annealed E7/HBPEAc-COOH blends, suggestive of induced smectic phase in the mixture. Wide angle X-ray diffraction (WAXD) technique revealed the existence of higher order mesophase(s).