Characterization of interfaces in core-shell polymers by advanced solid-state NMR methods

Cork-shell latexes based on poly(butyl acrylate) and poly(methyl methacrylate) and latexes of poly(butyl acrylate) and polystyrene were synthesized at high and low temperatures. In both cases the shell content was 33% in weight. Transmission electron microscopy and advanced NMR techniques have been used to investigate the structure of the system, and particular emphasis was put on the characterization of the interface between the two components. This interface can sensitively be analyzed using H-1 spin-diffusion techniques. Dynamic gradients at the interface are detected with varying filter strengths of the dipolar filter selecting mobile components and 2D wideline separation (WISE) NMR spectra in which structural and dynamic information are correlated. These experiments show distinct differences in the interface structure of systems synthesized at different temperatures and those with poly(methyl methacrylate) or polystyrene in the shell, respectively.