A pH/Temperature-Sensitive s-IPN Based on Poly(vinyl alcohol), Poly(vinyl methyl ether-alt-maleic acid) and Poly(vinyl methyl ether) Prepared by Autoclaving

A novel semi-interpenetrating polymer network (s-IPN) based on the entrapment of a thermosensitive polymer, the poly(vinyl methyl ether) (PVME), within a crosslinked 3D structure of poly(vinyl alcohol) (PVA) and poly(vinyl methyl ether-alt-maleic acid) (COP) was synthesized by an autoclaving process. The preparation method avoids the use of toxic crosslinkers and allows the simultaneous sterilization of material. The PVA/COP/PVME hydrogel were characterized by Fourier transform infrared spectroscopy, thermal techniques, swelling kinetic measurements, scanning electron microscopy, and rheological analysis. The entrapment of PVME within the hydrated polymer framework significantly modified its transition temperature at pH 7.4 and pH 3 conditions. The swelling kinetics of the s-IPN were dependent on pH (7.4, 3 and 1), and temperature (25 and 37 °C). The interpenetrated polymer chains reduced the internal pore sizes of crosslinked network without altering its elastic, solid-like behavior. The loading and in vitro release of 5-fluorouracil, a chemotherapeutic agent, from hydrogel systems were studied at different temperature and pH values. The hydrogels showed a sustained drug release up to 5 h at 37 °C, in different pH media. The s-IPN exhibited a promising performance for a range of biomedical applications, in particular, for the controlled drug delivery in response to the pH and temperature conditions.[Figure not available: see fulltext.]