SYNTHESIS AND CHARACTERIZATION OF HYDROPHILIC THERMOTROPIC BLOCK COPOLYETHERESTERS

The block copolyetheresters with a hard segment of poly(hexamethylene p,p'-bibenzoate) and a soft segment of poly(ethylene oxide) were prepared by melt polycondensation of dimethyl-p,p'-bibenzoate, 1,6-hexanediol, and polyethylene glycol (PEG) with molecular weights of 400, 1000, 2000, or 4000. These block copolyetheresters were characterized by intrinsic viscosity, GPC, FT-IR, H-1-NMR, and water absorption. The thermotropic liquid crystalline properties were investigated by DSC, polarized microscope, and x-ray diffraction. The block copolyetheresters exhibit smectic liquid crystallinity due to the polyester segment. The transitions are dependent on the molar content and the molecular weight of PEG used. The block copolyetheresters show high water absorption due to the hydrophilic nature of the poly(ethylene oxide) segment. The water absorption increases with increasing PEG content. As the molecular weight of PEG increases, the water absorption increases significantly. The results indicate that the water absorption of the poly(ethylene oxide) segment in the block copolymers is affected by the presence of polyester segments. (C) 1995 John Wiley and Sons, Inc.