5. Nanomaterials

Most nanomaterials currently available are nanocomposites or grafted materials (see figure 2 ). The former have two phases, as the nano-object is embedded in a matrix (mineral oxides or organic polymers) whose role is to shape the material. Silica is the most widely used matrix, due to its flexibility of use and wide range of compatibility with organic, inorganic and biological entities.

Grafted materials are obtained by forming a covalent bond between a nano-object and a solid support made of either silica or polymers. They correspond to a single phase: covalently bonded, matrix and nano-object are inseparable.