Synthesis and Characterization of Acrylic acid Grafted Styrene- Maleic anhydride Copolymer

Modification of Styrene-maleic anhydride copolymer, synthesized in toluene using benzoyl peroxide (BPO) as initiator, through graft copolymerization of hydrophilic monomer, acrylic acid, (AAc), has been carried out in aqueous medium by chemical and gamma radiation methods. Optimum conditions pertaining to maximum percentage of grafting were evaluated as a function of different reaction parameters. In case of chemical method, maximum percentage of grafting of AAc, (95%), was obtained using 14.56 x 10 moles of AAc, 12.38 x 10 moles of BPO at 70C in 180 min. Gamma radiation induced grafting of AAc produced maximum grafting, (855%), at a total dose of 68.04 kGy using 21.83 x 10 moles of AAc. Swelling studies of the grafted styrene-maleic anhydride copolymers, SMA-g-poly (AAc), has been studied as a function of temperature, time and pH. Maximum swelling (3290%) was observed at 37C in 12h at 9 pH for the grafted sample prepared by radiation method. The graft copolymers have been characterized by FTIR, XRD and Thermo gravimetric analysis. From the XRD and TGA data, a correlation between crystallinity and thermal behavior of the grafted copolymer has been observed. The graft copolymer was used as a drug carrier and the release of an antibiotic drug, ampicillin, was studied at pH 3.5 and pH 7.5.