PTFE-polystyrene core-shell nanospheres and nanocomposites

PTFE latexes with particles in the submicrometer size range were employed as seeds in the emulsifier-free styrene emulsion polymerization to obtain PTFE-polystyrene (PS) core-shell nanospheres. Stable latexes were generally obtained. Neither residual PTFE nor secondary nucleation was observed, thus leading to PTFE-PS core-shell latexes. By appropriately choosing the ratio between the styrene monomer and the PTFE seed in the reaction mixture, it is possible to obtain spheres with predetermined sizes and narrow size distribution. In all cases, a slightly hemispherical morphology was observed. Peculiar effects related to the high degree of segregation of PTFE cores and their small size, and possibly to the PTFE/PS interface, were observed.