Surface initiated polymerization (SIP) on nanoparticle surfaces: Demonstration of first principles and preparation of nanocomposite materials

To investigate the grafting of polymer chains onto nanoparticles (metal, semi-conductor, inorganic, etc) and nanostructured (patterned) surfaces, we have investigated anionic surface initiated polymerization (SIP) on a variety of surfaces. Understanding the surface chemistry issues involved is critical for future applications and protocols. SIP of polystyrene from Silicate and clay nanoparticles surfaces have been made by the living anionic polymerization method with 1, 1-diphenylethylene (DPE) initiation sites attached to nanoparticle surfaces using chlorosilane and amino functional groups. Model studies were initially done on flat Si-wafer surface and recently with Au surfaces. For the nanoparticles, the grafted polymers were cleaved and characterized by FTIR, NMR, AFM, TGA and SEC. Polymers grafted from nanoparticle surfaces show higher polydispersity and lower molecular weight than those formed in solution. We observed that diffusion of the monomer, stability of the initiator attachment to the surface, and aggregation of the particles controls the properties of the grafted polymers on particle surfaces. On the other hand, the use of the anionic polymerization method on surfaces allows the possibility of combining a variety of polymers (organic) with various nanoparticle and surfaces (inorganic) for the preparation of hybrid nanocomposite materials.