THERMALLY-INDUCED CORE-SHELL TYPE HYDROGEL BEADS HAVING INTERPENETRATING POLYMER NETWORK (IPN) STRUCTURE

Monodisperse hydrogel beads composed of calcium alginate and crosslink ed polyNIPAAm (N-isopropylacrylamide) were synthesized based on a simu ltaneous interpenetrating network process. With increasing the tempera ture above the phase transition temperature of polyNIPAAm, a core-shel l type of hydrogel beads was developed; polyNIPAAm-enriched core regio n and Ca-alginate-enriched outer shell layer were observed. The therma lly reversible formation of the core-shell double structure in the TPN hydrogel beads was applied for the temperature modulated drug release using indomethacin as a model drug.