Aerobic radical polymerization of hydrogels triggered by acetylacetone-transition metal self-initiation

The performance of hydrogel radical polymerization under ambient conditions is a major challenge because oxygen is an effective radical quencher and the steps to remove or neutralize it are time consuming and laborious. A self-initiating system consisting of transition metals and acetylacetone has been successfully developed. The system is capable of initiating free radical polymerization of hydrogels at room temperature under aerobic conditions, which is attributed to carbon radicals generated by the oxidation of acetylacetone. Some of these carbon radicals reduce oxygen to generate hydroxyl radicals, which together induce self-coagulation of hydrogels. The polymerization system was effective for a variety of monomer and hydrogel swelling and shrinking schemes, and the reaction remained successful when exposed to saturated oxygen. In conclusion, the results demonstrate that the present strategy is an effective approach to addressing the challenge of deoxygenation in polymer synthesis, and provides a convenient method for synthesizing multifunctional hydrogels under ambient conditions.