Fabrication of fast responsive, thermosensitive poly(N-isopropylacrylamide) hydrogels by using diethyl ether as precipitation agent

An effective strategy was developed and demonstrated to improve the properties of thermosensitive poly(N-isopropvlacrylamide) (PNIPAAm) hydrogel by using diethyl ether as a precipitation agent during the polymerization/crosslinking. Results reveal that the modified PNIPAAm hydrogels have the heterogeneous network structures and decreased LCSTs in a comparison with the normal PNIPAAm hydrogel. The modified PNIPAAm hydrogels also exhibit significantly improved sensitive properties, including fast response and stable, rapid, large magnitude oscillatory shrinking-swelling upon temperature cycles around lower critical solution temperature. In addition, fish DNA, used as a model drug, is loaded into the modified PNIPAAm hydrogels, the controlled release behaviors of the drug loaded hydrogels at different temperatures (22 and 37) are further examined. (C) 2007 Wiley Periodicals, Inc.