THE INFLUENCE OF DRYING METHOD ON THE PHYSICAL-PROPERTIES OF SOME GRAFT-COPOLYMERS FOR DRUG-DELIVERY SYSTEMS

Graft copolymers of methyl methacrylate (MMA) on various natural subst rates (carboxymethyl cellulose, hydroxypropyl cellulose, carboxymethyl starch and hydroxypropyl starch) were prepared in aqueous medium by t he eerie ion initiator method. Products were dried in two differents w ays: in ovens (O products) and by lyophilization (L products). The ext ent of graft copolymerization was measured in terms of grafting effici ency (GE), grafting (G), total conversion (CT) and crude grafting (CG) . As would be expected, by both drying methods almost identical values of grafting yields were obtained. Using scanning electron microscopy (SEM) some morphological particle size differences between O and L pro ducts were observed. These differences lead to different physical prop erties (particle size, moisture uptake, density and swelling capacity) of O and L products. Copyright (C) 1997 Elsevier Science Ltd. All rig hts reserved.