Drug release from pH-sensitive interpenetrating polymer networks hydrogel based on poly (ethylene glycol) macromer and poly (acrylic acid) prepared by UV cured method

Acrylate-terminated poly (ethylene glycol) (PEG) macromer was prepared by the reaction of PEG with acryloyl chloride. Photopolymerization of PEG macromer resulted in the formation of cross-linked PEG network. Interpenetrating polymer networks (IPNs) based on PEG and poly(acrylic acid) (PAA) was obtained via template polymerization of AA to the PEG network by UV curing. The swelling degree of the IPNs hydrogel increased with an increase of pH value due to the association-dissociation between carboxylic acid of PAA and ether of PEG through hydrogen bonding. The swelling-deswelling behavior proceeded reversibly for the IPNs upon changing pH. Release of indomethacin from the IPNs demonstrated ''on-off'' regulation with pH fluctuation.