CHARACTERIZATION OF INTERPHASES IN CORE-SHELL LATEXES BY SOLID-STATE NMR

Concepts for the characterization of composite latex particles by adva nced solid-state NMR methods are discussed. The techniques are based o n H-1 spin-diffusion experiments usually applied to detect heterogenei ties in polymers and polymer blends. In latexes, they allow one to cha racterize the morphology, including substructures in the interphase be tween core and shell. Motional heterogeneities within the phases are a lso detected. The techniques are used to characterize an extended seri es of core-shell particles composed of poly(n-butyl acrylate) (PBuA) a nd poly(methyl methacrylate) (PMMA) synthesized in semicontinuous two- step emulsion polymerization processes. The influence of process param eters such as synthesis temperature, crosslinking density in the core, shell content, particle size, and annealing are investigated.