Search

Semi‐interpenetrating polymer networks (semi‐IPNs) composed of chitosan and polyacrylamide (PAAm) hydrogels have been prepared, and the effect of changing pH, temperature, ionic concentration, and applied electric fields on the swelling of the hydrogels was investigated. The swelling kinetics increased rapidly, reaching equilibrium within 60 min. The semi‐IPN hydrogels exhibited a relatively high swelling ratios of 385%–569% at T=25°C. The swelling ratio increased with decreasing pH below pH=7 due to the dissociation of ionic bonds. The swelling ratio of the semi‐IPN hydrogels was pH, ionic concentration, temperature, and electric field dependent. Differential scanning calorimetry (DSC) was used to determine the volume of free water in the semi‐IPN hydrogels, which was found to increase with increasing PAAm content. [ABSTRACT FROM AUTHOR]

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]