The present invention discloses a process for producing a core-shell
polymer that comprises: (1) preparing a monomer solution which is
comprised of (a) at least one monomer, optional one crosslinking monomer
(b) a conjugate acid of a surfactant with a pKa of less than 14, and (c)
a controlled free radical polymerization agent; (2) preparing an aqueous
medium which is comprised of (a) water, and (b) a conjugate base of a
weak acid wherein the pKb of the base is less than 14; and (3) mixing the
monomer solution with the aqueous medium under conditions that result in
the in-situ formation of an emulsifier to produce a polymerization
medium, and (4) initiating free radical polymerization within the
polymerization medium to produce a core polymer, wherein the core
contains a free radical control agents, (5) adding a second monomer to
the polymerization medium containing the core polymer, and (6) allowing
polymerization to proceed in the presence of the free radical control
agent to produce the core-shell polymer.