Study And Preparation Of Graphene And Clay Nanocomposite Hydrogels

Hydrogels with excellent swelling/deswelling, responsiveness to external stimuli and biocompatibility properties have not only been widely used in our daily life, but also a good application prospect in drug delivery, chemical separation and so on. However, conventional polymeric hydrogels crosslinked by organic crosslinkers are usually mechanically weak, limiting the application of hydrogels to some extent. So, in recent years, finding a way to overcome this limitation and enhance the hydrogels has become a challenging problem in the scientific community. In the present paper, semi-interpenetrating polymer network (semi-IPN) and double network (DN) organic/inorganic nanocomposite hydrogels with excellent mechnical properties are prpepared by using inorganic clay or inorganic graphene oxide (GO) as crosslinker. The main work is as follows:1. pH-and temperature-responsive semi-IPN magnetic nanocomposite hydrogels (NC hydrogels) were prepared by using linear sodium alginate (SA), N-isopropylacrylamide (NIPAM) as monomer, Fe3O4nanoparticles as additive and inorganic clay as an effective multifunctional crosslinker. The effects of crosslinker and SA contents on various physical properties were investigated. Comparing with conventional chemically hydrogels crosslinked by N,N’-methylenebisacrylamide (BIS), the NC hydrogels exhibit high swelling ratios and good mechanical property.2. GO sheets were first prepared via an oxidation reaction in aqueous solution and then modified with3-(trimethoxysilyl)propylmethacrylate (TMSPMA) via the silanization. pH-and temperature-responsive semi-IPN nanocomposite hydrogels (PNIPAM/SA/GO hydrogel) with surface-functionalized GO as the crosslinker, NIPAM as the monomer and sodium alginate (SA) as an additive. The effects of crosslinker and SA contents on various physical properties were investigated. Comparing with conventional chemically hydrogels crosslinked by organic BIS, the PNIPAM/SA/GO hydrogels exhibit high swelling ratios and good mechanical property.3. On the basis of above studies, we prepared pH-and temperature-responsive DN hydrogels (PNIPAM/AA/GO hydrogel) with poly(N-isopropylacrylamide)(PNIPAM) as a tightly crosslinked1st network, poly(acrylic acid)(PAA) as a loosely crosslinked2nd network and graphene oxide (GO) as an additive. GO sheets were first prepared via an oxidation reaction and then dispersed in NIPAM aqueous solution via the silanization. Free-radical polymerization of NIPAM was carried out at20℃in a water bath, and then subjected to UV light, leading to the formation of pH-and temperature-responsive PNIPAM/AA/GO DN hydrogels. The effects of GO sheets and AA contents on various physical properties were investigated. Comparing with conventional chemically hydrogels crosslinked by organic BIS, the PNIPAM/AA/GO hydrogels exhibit fast deswelling and good mechanical property.