Synthesis of poly(N-isopropylacrylamide) hydrogels by radiation polymerization and cross-linking

A typical thermal reversibility of phase transition in agueous solution is shown by poly (N- isopropylacrylamide) [poly (NIPAAm)]. This is because it precipitates from solution above a critical temperature called the lower critical solution temperature (LCST) and dissolves below this temperature. The acquired hydrogel collapses above LCST, while it swells and expands below LCST (when it is crosslinked). In the paper, the idea is to apply a radiation-induced polymerization method for the synthesis of poly(NIPAAm) hydrogels. This method offers unique advantages for synthesis. Results show that the new method has synthesized poly (NIPAAm) hydrogels. Below LCST, the gels synthesized by lower doses swell to a higher extent than the more cross-linked gels. Above LCST, the swelling percentage increased until about 50 KG sub( gamma ) and then decreased with an increase in the dose.