Process for making hybrid acrylic star polymers with polysiloxane cores

Claim 1

An improved process for the preparation of a silicon-containing branched organic polymer including the steps of forming a linear addition arm polymer having a polyalkoxysilyl group as a substituent in an end portion of the molecules thereof, and then reacting by polycondensation the polyalkoxysilyl groups with each other to couple the polymer molecules with one another wherein the improvement comprises: 1) forming a linear acrylate and/or methacrylate block copolymer of molecules having two end portion by a group transfer polymerization process of acrylate and/or methacrylate monomers using a group transfer polymerization initiator in which one end portion of the copolymer molecules is formed containing as a substituent at least one crosslinkable polyalkoxysilyl group and the other end portion of the molecules is formed containing no crosslinkable polyalkoxysilyl substituent; and then 2) crosslinking the alkoxysilyl groups with one another among the copolymer molecules by a polycondensation reaction to form a copolymer having a crosslinked polysiloxy core and more than 4 linear polyacrylate and/or polymethacrylate arms attached thereto.