Dispersions of nanosilica in biocompatible copolymers

Dispersions of nanosilica in matrices of biocompatible copolymers were prepared by melt blending. Copolymers with variable molecular size at fixed hydrophilic/hydrophobic ratio and nanosilicas with different interfacial areas were studied. For comparison, a nanoclay was also investigated. The interfacial area played a relevant role in conferring peculiar properties on the nanohybrids. Amazingly, the macromolecule adsorbed on the nanosilica surface maintains some crystallinity which was quantitatively evaluated. In contrast, all the macromolecule anchored to the nanoclay surface is amorphous. The change of the crystalline state was reflected in the dielectric and the electrical conductivity properties. The micro-morphology revealed grape-like structures the size of which decreases with the silica content. These agglomerates were invoked to be responsible for the drastic change of the macromolecule thermal degradation. The copolymer/nanoclay showed a rather compact microstructure and a thermal degradation similar to that of pure macromolecule. (C) 2009 Elsevier Ltd. All rights reserved.