Preparation of fast responsive,temperature-sensitive poly(N-isopropylacrylamide) hydrogel

A new poly(N-isopropylacrylamide) (PNIPA) hydrogel was prepared by decreasing the temperature of polymerization/crosslinking reaction below the freezing point (–18°C). This PNIPA hydrogel shows a large swelling ratio at room temperature and exhibits a fast deswelling and reswelling rate in response to external temperature changes. These properties are attributed to the macroporous and regularly arranged network of this PNIPA hydrogel.