Novel Interpenetrating Networks (IPNs) Hydrogels Prepared In Situ by Liquid‐Phase Photopolymerization

Abstract

AbstractNovel interpenetrating networks (IPNs) hydrogels responsive to temperature were prepared in situ by liquid‐phase photopolymerization. The first network of the IPNs (poly isopropyl acrylamide) were formed with a special kind of hectorite (Laponite XLS) modified by tetrasodium pyrophosphate as cross‐linker and 2‐oxogultaric acid as photoinitiator. The samples were subsequently immersed in an acrylamide (AAm) aqueous solution for at least one day for preparing IPNs hydrogels, in which acrylamide aqueous solution containing N,N′‐Dimetyl acrylamide (MBAA) as cross‐linker and 2‐oxogultaric acid as photoinitiator. Then the second networks were in situ formed by introducing ultraviolet light irradiated PNIPAAm gels. The swelling/deswelling behaviors of IPNs hydrogels were measured. Compared with the corresponding nanocomposite PNIPAAm hydroges(NC hydrogels), chemically cross‐linked PNIPAAm and PAAm IPNs hydrogels, the results indicate that the new IPN hydrogel has a faster deswelling rate above its LCST (≈32 °C). The effect was explained as being an additional contribution of the PAAm chains in IPN hydrogels, which may act as a water‐releasing channel when the hydrophobic aggregation of PNIPA takes place.