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 prepa red by melt polycondensation of dimethyl-p,p'-bibenzoate, 1,6-hexanedi ol, and polyethylene glycol (PEG) with molecular weights of 400, 1000, 2000, or 4000. These block copolyetheresters were characterized by in trinsic viscosity, GPC, FT-IR, H-1-NMR, and water absorption. The ther motropic liquid crystalline properties were investigated by DSC, polar ized microscope, and x-ray diffraction. The block copolyetheresters ex hibit smectic liquid crystallinity due to the polyester segment. The t ransitions are dependent on the molar content and the molecular weight of PEG used. The block copolyetheresters show high water absorption d ue to the hydrophilic nature of the poly(ethylene oxide) segment. The water absorption increases with increasing PEG content. As the molecul ar weight of PEG increases, the water absorption increases significant ly. The results indicate that the water absorption of the poly(ethylen e oxide) segment in the block copolymers is affected by the presence o f polyester segments. (C) 1995 John Wiley and Sons, Inc.