Inorganic clusters in organic polymers and the use of polyfunctional inorganic compounds as polymerization initiators

Silicon oxide or metal oxide clusters or small particles with polymerizable organic groups covalently bonded to their surface can be copolymerized wit h organic monomers by Various polymerization techniques. Whereas the prepar ation and properties of the polymers reinforced by R8Si8O12 have already be en well investigated, analogous materials with incorporated transition meta l oxide clusters are only beginning to show their potential as an interesti ng new class of inorganic-organic hybrid polymers. In the second part of th e article, approaches are reviewed in which the inorganic building block se rves as an initiator for polymerization reactions. This results in material s in which the organic polymer is grafted from an inorganic core. Most work has been done with surface-modified silica particles. Free radical polymer izations and atom transfer radical polymerizations with macroinitiators are summarized. The latter method results in polymeric particles in which an i norganic core is surrounded by an organic polymer shell. A new approach is the use of polyfunctional inorganic molecules or molecular clusters as init iators.