High strength nanocomposite hydrogels with outstanding UV-shielding property

A novel series of nanocomposite hydrogels (TAD gels) with high mechanical strength and excellent UV-shielding property were prepared by in situ free-radical copolymerization of acrylamide (AM) and N,N-dimethylacrylamide (DMAA) in aqueous solutions of TiO₂ nanoparticles (TiO₂ NPs). It was found that the TiO₂ NPs were uniformly dispersed in the copolymer matrix and acted as inorganic crosslinking agents in TAD gels owing to their hydrogen bonding interactions with polymer chains. The TAD gels exhibited excellent mechanical properties such as large elongations at break, high elastic moduli, and ultimate stresses, all of these properties as well as swelling ratios of TAD gels could be easily controlled by changing the AM ratios and TiO₂ contents in the initial solutions. In addition, the TAD gels with low AM ratios could be prepared into thin films in a customized Teflon model and these films showed high transparency in visible light but could completely block the UV light with wavelength below 366 nm and prevent the methylene blue from degradation under UV irradiation.