Physically crosslinked poly (vinyl alcohol)/poly (acrylic acid) hydrogels were prepared by freeze thaw processing. The hydrogels were formed in, either, water or a water/DMSO mixture and the chemical, mechanical, and thermal properties were determined by FTIR analysis, rotational rheometry and modulated DSC respectively. The results indicate that the hydrogels containing DMSO are significantly stronger than those containing water alone at temperatures between 20 and 40 degrees C. Materials with different characteristics can be created by varying the solvent and the polymer feed ratios. DSC analysis indicated that thermal transitions are present at temperatures that may make these hydrogels useful in temperature sensitive drug delivery systems. (c) 2006 Springer Science + Business Media, Inc.