Ring-opening metathesis polymerization on well defined silica nanoparticles leading to hybrid core-shell particles

The grafting and catalytic activity of a metathesis catalyst on well defined silica nanoparticles is described. The aim of this was to test the catalysis properties of a ligand-linked catalyst in ring-opening metathesis polymerization and also the possibility to obtain controlled hybrid materials. This was carried out by reaction of a synthesized hydroxy functionalized phosphine Cy2P(CH2)(10)OH with Cl2Ru(PPh3)(2)(=CH - Ph), leading to a metathesis catalyst bearing a hydroxy group at the end of a ligand. This group was reacted with well defined silica nanoparticles with a diameter of 200 nm, that had acyl chloride functions at their surface. The grafting density was calculated from thermogravimetry experiments and found to be around 7 mumol m(-2). The activity of the catalyst was tested for the ring-opening polymerization of norbornene. This showed that a fraction as high as 30% of the catalyst could initiate the polymerization and that the polymerization proceeded until completion. TEM characterization revealed that in diluted solutions, core - shell morphologies could be obtained. The efficiency of the polymerization may therefore lead to control of the thickness of the polymer coating.