Preparation of polystyrene-polyisoprene core-shell nanoparticles for reinforcement of elastomers

Latex-formed core-shell nanoparticles composed of cross-linked polystyrene (PS) core and polyisoprene (PI) shell were successfully synthesized by means of a two-stage emulsion polymerization. The PS core possessed a Z-average diameter of 50.3 nm, and the PS-PI particles took a spherical shape with a Z-average size of 50-70 nm in diameter. Shell thickness was controlled by varying isoprene loading. Necessary interphase interactions between the core and shell domains were also achieved by grafting and swelling polymerization. Latex compounding method was employed to prepare the filled elastomer compounds. As expected, the PS-PI core-shell nanoparticles exhibited excellent reinforcement to elastomeric matrix, enhancing the tensile strength of the styrene-butadiene rubber by approximately 400%. The lower density, better interfacial interactions, and latex compounding process would benefit the PS-PI nanoparticles reinforced elastomer nanocomposites in energy saving.