Interpenetrating polymer networks (IPNs) composed of poly(vinyl alcohol) (PVA) and poly(N-isopropylacrylamide) (PNIPAAm) were prepared by the sequential-IPN method. The thermal characterization of the IPNs was investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). Depression of the melting temperature (T-m) of the PVA segment in IPNs was observed with increasing PNIPAAm content using DSC. DEA was employed to ascertain the glass-transition temperature (T-g) of IPNs. From the result of DEA, IPNs exhibited two T-g values, indicating the presence of phase separation in the IPNs. The thermal decomposition of IPNs was investigated using TGA and appeared at near 200degreesC. (C) 2003 Wiley Periodicals, Inc.