This invention discloses a process for synthesizing a modified crosslinked elastomeric particle which comprises a two-step polymerization of a conjugated diolefin monomer and a vinyl aromatic monomer by emulsion polymerization, wherein the particle is synthesized by the steps of (1) polymerizing a conjugated diolefin monomer, alone or in combination with a vinyl aromatic monomer, and optionally a crosslinking monomer, to create a crosslinked elastomeric core having residual double bonds and an outer surface; (2) polymerizing a monomer of a vinyl aromatic monomer, alone or in combination with a diolefin monomer, to create a polymeric shell, wherein the polymeric shell is grafted to the outer surface of the polymeric core by reacting with the residual double bonds of the polymeric core; and (3) coagulating the core-shell emulsion latex solution to recover the particles.