Preparation of intelligent calcium alginate/PNIPAAm interpenetrating network hydrogel beads

A thermo- and pH-sensitive interpenetrating network hydrogels beads were prepared with both calcium alginate and PNIPAAm hydrogels which were synthesized by free-radical aqueous solution polymerization using APS (ammonium persulphate)/Na₂S₂O₅ (Sodium pyrosulfite) as redox initiators in a simultaneous interpenetrating network process. The effects of the initiator concentration, monomer concentration, NIPAAm/alginate ratio, the solution pH values on the gel swelling performance in different temperatures and pH solutions were discussed. Results show that the IPN hydrogel beads exhibit thermo- and pH-sensitive swelling ratio characteristics. Therefore, the IPN hydrogels may be useful in the field of controlled drug delivery.