ABNORMAL PH SENSITIVITY OF POLYACRYLATE-POLYURETHANE HYDROGELS

A series of polyacrylate-polyurethane networks (PUA) were synthesized and their pH-sensitive behaviors were studied. An unexpected swelling- deswelling behavior was observed as the composition changed. Dynamic m echanical thermal analysis and differential scanning calorimetry were used to initially explain this phenomenon. By applying small-angle X-r ay scattering and wide-angle X-ray diffraction simultaneously, a speci fic multiphase-transition process could be clearly detected, which mad e the mechanism of the observed abnormal pH sensitivity more explicit. (C) 1998 John Wiley & Sons, Inc.