New polymeric systems with controlled release action: a light scattering investigation

New controlled release water soluble formulations of sorbic (2,4-hexadienoic) acid (SA) were prepared and their inhibitory activity on mycelium growth of Fusarium oxysporum f.sp. radicis-cucumerinum was evaluated. The new products are epoxidized polymers of polyvinylpyrrolidone (PVP) containing covalently bonded SA (polymeric esters of SA) and complexes of PVP with hydrogen bonded SA, characterized by controlled release of SA. It was shown that the polymeric complexes of SA with PVP were more effective fungicidal agents than SA polymeric esters. In all cases the activity of polymeric derivatives (esters and complexes) was increasing by lowering the molecular weight of the polymeric carriers. We have performed static and dynamic light scattering measurements in a series of PVP/SA water soluble polymeric derivatives. The light scattering data suggest that the polymer structure and/or solution conformation may be important determinants of the inhibitory effect (bioactivity).