Living anionic surface initiated polymerization (LASIP) of isoprene from silica nano- and glass particles

Living anionic surface initiated polymerization (LASIP) of isoprene from initiator modified silica nano- and glass particles is conducted. In order to prepare polyisoprene-silica composites, the surfaces of the particles are modified with three coupling agents, each bearing a diphenyl ethylene (DPE) moiety with different alkyl-spacer lengths, thus separating the DPE moiety in different distance from the particles’ surfaces. Surface initiated polymerization reactions from modified particle surfaces are performed by using n-BuLi to activate the DPE units and benzene as solvent via LASIP. Grafted polyisoprene-silica composites are analyzed via TGA, resulting in grafting densities of the produced inorganic-polymer composites in the range from 0.10 to 0.24 chains/nm2. Analysis via GPC reveals polydispersity values ranging from 1.1 to 1.7. The final microstructure of the grafted polyisoprene is investigated via NMR, revealing 15% 1,2, 35% cis-1,4 and 50% trans-1,4, irrespective of the spacer length of the DPE bearing coupling agent.