CONICET | Buscador de Institutos y Recursos Humanos

Polymerclay nanocomposites were prepared from dimethacrylate monomers,commonly used in dental restorative resins, and different amounts of an organicallymodified silicate (Montmorillonite). Rheological characterization showed that the claymodified methacrylate suspensions displayed a shear thinning behavior even at lowfiller concentrations. The photopolymerization process was hardly affected by thepresence of the silicate filler, thus 2 mm thick samples containing 3 wt% clay wereextensively cured. Transmission Electron Microscopic revealed that the Montmorilloniteplatelets were either packed together in a disordered arrangement (intercalated) ordispersed as isolated nanoparticles (exfoliated). Nevertheless, for all formulations evenat low clay loading, intermediate size aggregates of about 1 μ were present and theirfraction increased as the filler amount increased. They presence of the clay was foundto have no major effect on the flexural modus and compressive yield strength thenanocomposites. Moreover, water uptake of nanocomposites containing 3 wt% claywas about 10-15 % higher than that in unfilled monomers. Modification in the claysurface with alternative organic cations is certainly necessary in order to increasecompatibility between the clay and the surrounding monomer and to achieve an optimaldispersion of the clay into the polymer matrix.