Characterization of Vinyl Polymer/Silica Colloidal Nanocomposites Using Solid State NMR Spectroscopy: Probing the Interaction between the Inorganic and Organic Phases on the Molecular Level

Abstract

Colloidal poly(4-vinylpyridine)/silica and polystyrene/silica nanocomposite particles comprising 38% and 48% silica by mass, respectively, have been characterized by solid-state NMR spectroscopy in order to probe the nature of the molecular interactions between the polymer and silica phases. For P4VP/silica nanocomposite particles, our results indicate hydrogen bond formation between the pyridine nitrogen and a surface hydroxyl proton. In contrast, a π-interaction between the aromatic ring and the silica surface is the most likely model for the PS/silica nanocomposite particles. Nonspecific binding interactions do not appear to play an important role in nanocomposite particle formation in either case. The high-resolution proton−carbon-13 and proton−silicon-29 correlation experiments used to extract this information are a novel combination of multipulse proton decoupling and Lee−Goldberg cross-polarization.