Preparation and characterization of end-alkoxysilylated polystyrene and the grafting behaviors onto inorganic pigments. II. Utilization of 4-triethoxysilyl-α-methylstyrene

Abstract

Novel polystyrene was prepared with triethoxysilyl (TES) groups at the end of the chain, and the grafting behaviors of the resulting polymer onto silica, alumina, and titania were studied. TES groups were introduced by the reaction between living polystyryl anion and 4-triethoxysilyl-α-methylstyrene (1) in THF at 195 K. The end-functional polymer was characterized by GPC, 1 H-NMR, and TLC. It was confirmed that the polymer had several units of 1 at the chain end and a fairly narrow molecular weight distribution. TES groups in the present polymer were found to be hydrolyzed with both acids and bases such as mono-n-butylphosphate (MBP) and tetrabutylammonium hydroxide (TBAH), respectively. The polymer was effectively grafted onto silica and alumina in toluene in the presence of MBP and TBAH, respectively. The amount of graft, estimated by thermogravimetry, changed with the selection of substrates and catalysts ; about 2 mg/m 2 at the highest. The change in the amount of graft can be explained by the amount of effective acidic- or basic-hydroxyl groups on the substrate surfaces. However, titania received the largest amount of graft in the absence of catalyst. This may be because the strong acidic sites on the surface of titania act as a hydrolytic catalyst. The present polymer is expected to find wide application as a macromolecular dispersant for various types of inorganic pigments.