HYDROPHILIC THERMOTROPIC BLOCK COPOLYETHERESTERS WITH POLY(PENTAMETHYLENE P,P'-BIBENZOATE) SEGMENTS

Block copolyetheresters 1 with poly(pentamethylene p,p'-bibenzoate) se gments and poly(ethylene oxide) segments were prepared by melt polycon densation of dimethyl p,p'-bibenzoate, 1,5-pentanediol, and poly(ethyl ene glycol) (PEG) with molecular weights of 400, 1000, or 2000. The H- 1 NMR analysis shows that the feed mole ratio of PEG to dimethyl p,p'- bibenzoate determines the composition of the block copolyetheresters. The differential scanning calorimetry (DSC) results indicate that some block copolyetheresters exhibit a monotropic smectic liquid-crystalli ne phase due to the poly(pentamethylene p,p'-bibenzoate) segments. The transitions depend on the content and the molecular weight of the PEG . The block copolyetheresters 1 show high water absorption due to the hydrophilic nature of the poly(ethylene oxide) segments. The water abs orption increases with increasing PEG content. As the molecular weight of PEG increases, the water absorption increases significantly.