Keywords: nanocomposites, layered mineral, in situ polymerisation, polydimethylsiloxane, poly(&, #949, -caprolactone), syndiotactic polystyrene, nanotechnology, nanofillers
The in situ polymerisation for the elaboration of nanocomposites materials with controlled properties
The paper deals with the development of experimental processes, which allow the synthesis of organic-inorganic hybrid materials based on polysiloxane, prepared in the presence of HTiNbO5 nanolayered synthetic mineral, via in situ intercalative polymerisation of cyclosiloxanes and sol-gel technique from alkoxysilanes. A comparative study of these different systems demonstrated the influence of the preparation process on the nanocomposite structure and the evaluation of their different properties pointed out the drastic influence of the chemical grafting. Nanocomposites based on poly(ε-caprolactone) (PCL) have been also prepared by coordination catalysis through metallic catalyst previously grafted onto mineral sheets. The grafting reaction of the polymer chains is possible directly from the mineral oxide without preliminary intercalation by quaternary ammonium ions as usually described in the literature. Only a few examples are known for nanocomposites directly prepared from non-modified mineral. All the nanocomposites had greater mechanical properties and thermal stability than pure PCL. A biodegradation study of these materials has been carried out to evaluate the influence of the nanofiller on the matrix biodegradability. The nanofiller is claimed to play a catalytic role on the PCL degradation. Finally, a preliminary study has shown that coordination catalysis with an intercalation of metallocenes compounds can be used to prepare nanocomposites based on syndiotactic polystyrene in the presence of organo modified montmorillonite.