Structural design of PNIPA-based intelligent hydrogels via porous silica templates

Abstract

Intelligent temperature-sensitive hydrogels have been synthesized using a hierarchically organized, porous silica gel as template. The organic gels were obtained by three-dimensional copolymerization of N-isopropylacrylamide and N,N'-bis(acryloyl)cystamine in the free volume of a monolith of a porous silica gel. After characterization, the silica matrix was dissolved in alkali. Unexpectedly, the remaining organic polymer showed similar properties to a gel obtained in homogeneous solution. The shape of the inorganic mould was retained in the purely organic hydrogel even after dissolution of the inorganic part and it showed the ability to collapse under enhanced temperatures. The collapse rate of the gel prepared via the template synthesis was much higher compared to gels prepared conventionally.