Semi-interpenetrating polymer networks (semi-IPNs) composed of polyacrylic acid (PAA), and chitosan or N-(3-chloro-2-hydroxypropyl)trimethylammonium chloride (Quat-188) modified chitosan were synthesized. To fabricate the semi-IPN, acrylic acid (AA) was polymerized and crosslinked in the presence of unmodified and Quat-188 modified chitosan. The wet strength of the semi-IPNs improved with the increase in molecular weight of chitosan, chitosan to PAA ratio and by Quat-188 modification. Both

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... ied and unmodified semi-IPNs swelled in buffer solutions. Swelling was pH dependent. The mode of encapsulation and release of two different types of drugs from these semi IPNs was studied. Effects of various parameters on encapsulation and release of AgNO3 and mafenide acetate from these semi-IPNs were investigated. The semi-IPN hydrogel encapsulated 10 mmol/L AgNO3 (100% of added drug) in 5min and released 4% of it in 2h. In case of mafenide acetate, pH dependent encapsulation and controlled release was observed. It was observed that drug-semi IPN interaction strongly influences the encapsulation and release behavior. Freezable water associated with the hydrogels also played an important role for the encapsulation and release of drug.