MICROWAVE RADIATION INDUCED SYNTHESIS OF HYDROXYPROPYL METHYLCELLULOSE-GRAFT- (POLYVINYLALCOHAL-CO-ACRYLIC ACID) POLYMERIC NETWORK AND ITS IN VITRO EVALUATION.

A microwave induced irradiation synthesis, was proposed for the preparation of hydroxypropyl methylcellulose-graft-(polyvinylalcohal-co-acrylic acid) hydrogels. The hydrogels were separately synthesized by using microwave irradiation method and conventional water bath heating method. Moreover, the prepared hydrogels were loaded with an antihypertensive drug, captopril. Chemical groups, thermal stability and surface morphology of these hydrogels were characterized by FT-IR, DSC and SEM. Swelling ratios of the gels were measured gravimetrically at'pH 1.2 and 7.4. Results showed that micrographs obtained from scanning electron microscopy (SEM), revealed that gels synthesized using microwave irradiation had more uniformly porous network structures. The uniformity in porosity was due to rapid and instantaneous penetration of microwave energy throughout the surface and they had higher swelling ratios in comparison to hydrogels synthesized by water bath method. Thermal analysis (DCS and TGA) depicted that crosslinked polymers were more stable. FT-IR analysis had confirmed the formation of the new polymeric network. X-ray diffractogram revealed that crystallinity of HPMC was reduced in hydrogel prepared by microwave radiation. It had also been observed that high crosslinking density diminish swelling of hydrogel. A stable network of hydroxypropyl methylcellulose (HPMC), poly(vinylalcohal) (PVA) and acrylic acid was developed in shorter time period under influence of microwave radiations.