A nuclear magnetic resonance study on the adsorption of poly(methyl methacrylate) at a solid/liquid interface

Abstract

AbstractThe adsorption and desorption behaviour of tactic poly(methylmethacrylate) (PMMA) chain on silica gel from chloroform solution are investigated by using high‐resolution NMR spectroscopy.The conformation of PMMA chains adsorbed on silica and the effects of polar additives on polymer adsorption are discussed.It is shown that the adsorption of PMMA on silica surface is so strong as to restrict highly the polymeric motion of PMMA at segmental level. The conformation of PMMA adsorbed on silica gel surface is considered to be a uniformly adsorbed and relatively compressed form. The NMR technique is very effective to estimate the fraction of segments of which the segmental motion is restricted because of the adsorption on silica gel.The methanol/silica interaction is stronger than the PMMA/silica interaction, and methanol reduces rapidly PMMA adsorption on silica. The rate of adsorption displacement of PMMA by methanol is relatively rapid and PMMA almost reaches the equilibrium adsorption value within 30 min at room temperature.