title: In situ synthesis of polysulfides covalently bonded to silica.
abstract: Silanol groups, triple bond SiOH, on the surface of silica were esterified with unsaturated alcohols and long-chain alcohols bearing thiol groups. The modified silicas obtained were used as substrates for a vulcanization-analogous reaction with sulfur catalyzed by zinc dimethyldithiocarbamate. Surface-esterified thiols could be smoothly converted to bridged polysulfides bonded to the silica surface, whereas the use of surface-esterified unsaturated alcohols led to removal of the surface-esterified alcohol from the silica surface. The materials were characterized by solid-state NMR and thermal and microanalytical analysis. The linking of surface-esterified alkenols and thiols by sulfide bridges was investigated by a numerical model for a flat surface. This showed that for a typical density of 3-4 micromol/m(2) surface groups, a statistical maximum of 70-75% of groups could be linked by S(n) bridges (n=2-4).
authors.affiliation: Industrial Research Limited, P.O. Box 31-310, Lower Hutt, New Zealand. g.ossenkamp@irl.cri.nz
authors.forename: Gabriel C
authors.initials: GC
authors.lastname: Ossenkamp
authors.forename: Tim
authors.initials: T
authors.lastname: Kemmitt
authors.forename: Jim H
authors.initials: JH
authors.lastname: Johnston