A novel class of nanocomposite hydrogels (NC gels) with a unique organic / inorganic network structure was synthesized by in-situ free-radical polymerization of N-isopropylacrylamide (NIPA) or N,N-dimethylacrylamide (DMAA) in the presence of inorganic clay (hectorite). Since NC gels are composed of a unique organic / inorganic network structure, which consists of exfoliated clay platelets uniformly dispersed in an aqueous medium with a number of flexible polymer chains linking them together, NC gels exhibit high transparency, high degrees of swelling, and superb mechanical properties with extraordinarily large deformations. Also, NC gels formed from thermo-sensitive polymers, e.g. PNIPA, exhibit rapid temperature-response in transparency and gel volume (de-swelling) at the lower critical solution temperature (LCST). All the properties of NC gels are very different from those of conventional, chemically-crosslinked hydrogels (OR gels). Here, we evaluated various properties of NC gels from a biomaterials point of view, such as mechanical toughness (capable of sewing), absorption (water and saline), purification and extraction, drying (effect of cover film), coexistence of absorption and drying, sterilization (by autoclave and γ-ray irradiation), preliminary implantation (implanted to rabbit intramuscularly) and blood compatibility. These results indicate that NC gels are promising as soft biomaterials with blood compatibility as well as high transparency, absorbing power and mechanical properties.

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