Radiation preparation and thermo-response swelling of interpenetrating polymer network hydrogel composed of PNIPAAm and PMMA

Interpenetrating polymer network (IPN) hydrogel composed of hydrophilic pol y(N-isopropylacrylamide) (PNIPAAm) and hydrophobic poly(methyl methacrylate ) (PMMA) were synthesized by sequential IPN method using gamma-rays from Co -60 source. Compared with pure PNIPAAm hydrogel, PNIPAAm/ PMMA IPN hydrogel not only behaved with obvious temperature sensitivity, but also had higher mechanical strength. The shrinking rate of the prepared IPN hydogel was sl ower than that of PNIPAAm hydrogel and the relative shrinkage was higher th an that of PNIPAAm hydrogel. The IPN hydrogel with less PMMA was not stable while with more PMMA it was quite stable. In addition, the release of Meth ylene Blue (MB) from the IPN hydrogel was slower than that from PNIPAAm hyd rogel as well. (C) 2000 Elsevier Science Ltd. All rights reserved.