Fluorescence Studies of Polymer Diffusion Across Interface

We investigate the influence of surface properties on the kinetics of polymer diffusion across interfaces of films prepared from several different types of poly(n-butyl methacrylate) [PBMA] core-shell latex particles. A series of core-shell PBMA microspheres containing different amounts of methacrylic acid groups in their shell were prepared by three- stage emulsion polymerization. PBMA latex with poly(ethylene oxide) [PEO] chains at the surface was prepared by dispersion copolymerization of BMA with PEO macromonomer. Each pair of latex, one labeled with a donor (phenanthrene), the other, with an acceptor (anthracene), allows us to use direct non-radiative energy transfer experiments to follow polymer interdiffusion in their latex films. The interdiffusion was found to be significantly retarded but not suppressed, either by the presence of the acid groups in the latex shell, or by their salts. Neutralization of the acid groups by Ba2+ had a larger effect than Na+ on slowing down the polymer diffusion. On the other hand, PEO chains at the latex surface was found to promote interdiffusion in the early stages of film formation and aging.