Synthesis and characterization of polyhedral oligomeric silsesquioxane hybrid co-crosslinked poly(N-isopropylacrylamide-co-dimethylaminoethyl methacrylate) hydrogels

Polyhedral oligomeric silsesquioxane hybrid temperature and pH double-responsive hydrogels with organic-inorganic co-crosslinked networks are synthesized by in situ, free-radical polymerization of N-isopropylacrylamide and dimethylaminoethyl methacrylate in the presence of both organic crosslinker N,N-methylenebis(acrylamide) (BIS) and inorganic crosslinker octavinyl polyhedral oligomeric silsesquioxane (OvPOSS) in tetrahydrofuran media. The resulting hydrogels (OR-OvP gels) display obvious temperature and pH double responsiveness, OvPOSS particles dispersed in polymer make a dominant effect on the properties of gels. With the increase of OvPOSS, the aggregation of particles on nano- or microscale happens and causes a considerable change on the properties of gels, such as the lower critical solution temperature and better compression strength. Specially, the interconnected microporous structure of gels ascribed to the microphase separation results in faster deswelling rate, which makes the gel become attractive. Besides, the crosslink by BIS intensifies the heterogeneity of gels significantly, which could also be used to adjust the properties of gels. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1494-1504