Synthesis of hairy acrylic core-shell particles as toughening agents for epoxy networks

Hairy poly(butyl acrylate) (PBuA) core-shell particles with a crosslinked s hell were prepared by soap-free emulsion polymerization. The incorporation of the hairy structure was obtained either by surface polymerization of a m ethacrylate (MMA) terminated to poly(ethylene oxide) (PEO), or by physical adsorption of poly(ethylene oxide) poly(propylene oxide) (PPO)-poly(ethylen e oxide) triblock copolymers. The particle shell was crosslinked during the synthesis so as to keep the integrity and morphology of the particle upon curing the epoxy network. particle sizes and size distributions were determ ined both by quasi-elastic light scattering and transmission electron micro scopy. particle morphology was investigated by electron and atomic force mi croscopies. The presence of the poly(ethylene oxide) layer was evidenced by direct analysis of the latexes by means of H-1 NMR spectroscopy. Mixing of the core shell rubber particles with the reactive epoxy and processing of the toughened-epoxy networks are described. The influence of the hairy laye r (with regards to density and PEO chain length) on particle dispersion wit hin the epoxy network, the resulting rheological behaviour of the core-shel l (CS)/prepolymer epoxy blends, and mechanical properties of the modified e poxy were examined and discussed.