Nanosized hairy grains: A model system to understand the reinforcement

We have prepared nanosized hairy grains by grafting long polydimethylsiloxane chains onto silica particles of radius approximate to 15 nm. The synthesis method allows the particles to keep in truly stable suspension at any stage of their preparation. In dilute suspension, these hairy grains behave as repulsive soft spheres. Above a certain concentration (of the order of 0.1 g/cm(3)), the polymer chains form bridges between the particles due to physical adsorption, which induces a gelation of the suspension. If the solvent is completely removed, a reinforced elastomer is formed. Its mechanical properties (which can be exceptionally good) are entirely determined by the design of the ultimate particles.