Quantitative measurement of core coverage in core-shell particles by solid-state1H NMR spin-diffusion experiments

Abstract

The shell material core coverages of two-phase core-shell particles are determined quantitatively by NMR spin-diffusion experiments. A simple relation is derived between the specific surface (ratio of core surface and core volume) and the core coverage of acrylic core-shell particles in the solid state. Through calibration with a reference sample of known core coverage, the core coverage of the other samples can then be evaluated. The values of core coverages determined by spin-diffusion become more accurate as the core coverage becomes smaller. In a series of poly(methyl methacrylate) (PMMA) and poly(butyl acrylate) core-shell latices, the core coverage was found to vary between 43 and 80%. Additionally, information about the global particle morphologies is derived from a quantitative comparison of the specific surface and the particle diameter measured by dynamic light scattering.