CORE-1ST SYNTHESIS OF STAR POLYMERS WITH POTENTIALLY IONOGENIC BRANCHES

Star-shaped macromolecules have been synthesized anionically by initiating the polymerization of a suitable monomer from "living" multifunctional cores. These cores result from the anionic polymerization of a small amount of divinylbenzene under very specific conditions in dilute tetrahydrofuran (THF) solution. The main advantage of this method is to allow functionalization at the outer end of the branches. Star block copolymers can also be synthesized by this method, provided the polymerization of the second monomer can be initiated by the carbanions of the first one. An alternate method has been attempted. Initiating cores comprising short polystyrene arms resulted from an arm-first synthesis. These cores were used to initiate the polymerization of tert-butyl acrylate, the branches being grown from the cores. This latter method has the advantage of allowing a better control of the functionality of the cores and yielding rather well-defined polymers. The monomer used in this work was tert-butyl acrylate, a monomer which can be polymerized anionically to living polymers if lithium chloride is present in the reaction medium as indicated by Teyssie. Star-shaped poly(tert-butyl acrylate) samples were obtained as well as star block copolymers, the branches of which are polystyrene-poly(tert-butyl acrylate) block copolymers. These species were characterized adequately.