THE INTERACTION OF WATER WITH POLYURETHANES CONTAINING BLOCK COPOLYMER SOFT SEGMENTS

The saturation water uptake and nonfreezing water, determined as a function of temperature in a polyurethane containing the pure polyethylene oxide soft segment (I) and in polyurethanes containing block copolymer polyethylene oxide/polypropylene oxide soft segments (II), show significantly different behavior. In sample I, the water content and nonfreezing water are only weakly dependent on temperature from 276 to 333 K. In the samples based on II, with various ratios of the hydrophilic and hydrophobic segments, there is a strong decrease in solubility with temperature and a steep drop above 303 K. The nonfreezing water exhibits a parallel trend. This behavior is interpreted in terms of the temperature-dependent phase compatibility of the polyethylene oxide and polypropylene oxide segments of II.