Preparation and characterization of light-cured methacrylate/montmorillonite nanocomposites

V.L.MUCCI, C.J. PEREZ, C. I. VALLO

POLYMER INTERNATIONAL

JOHN WILEY & SONS LTD

Año: 2010 vol. 60 p. 247 - 254

0959-8103

Polymer–clay nanocomposites were prepared from dimethacrylate monomers, commonly used in dental restorative resins, and different amounts of an organically modified silicate (Montmorillonite). Rheological characterization showed that the clay modified methacrylate suspensions displayed a shear thinning behavior even at low filler concentrations. The photopolymerization process was hardly affected by the presence of the silicate filler, thus 2 mm thick samples containing 3 wt% clay were extensively cured. Transmission Electron Microscopic revealed that the Montmorillonite platelets were either packed together in a disordered arrangement (intercalated) or dispersed as isolated nanoparticles (exfoliated). Nevertheless, for all formulations even at low clay loading, intermediate size aggregates of about 1 ì were present and their fraction increased as the filler amount increased. They presence of the clay was found to have no major effect on the flexural modus and compressive yield strength the nanocomposites. Moreover, water uptake of nanocomposites containing 3 wt% clay was about 10-15 % higher than that in unfilled monomers. Modification in the clay surface with alternative organic cations is certainly necessary in order to increase compatibility between the clay and the surrounding monomer and to achieve an optimal dispersion of the clay into the polymer matrix.