Swelling Characterizations of the Interpenetrating Polymer Network Hydrogels Composed of Polymethacrylic Acid and Alginate.

A temperature- and pH-responsive interpenetrating polymer network (IPN) hydrogels constructed with polymethacrylic acid (PMAAc) and sodium alginate (SA) by sequential IPN method was studied. The characterizations of IPN hydrogels were investigated by fourier transform infra-red spectroscopy (FT-IR), differential scanning calorimetry (DSC) and swelling tests under various conditions. IPN hydrogels exhibited a relatively high swelling ratio in the range of 183-916% at 25°C. The swelling ratio of PMAAc/SA IPN hydrogels depended on pH, temperature and ionic concentration. DSC was used for the quantitative determination of the amounts of freezing and non-freezing water. The amount of free water increased with increasing PMAAc content in the IPN hydrogels. [ABSTRACT FROM AUTHOR]