Linear and star block copolymers of styrenic macromonomers by anionic polymerization

We describe the synthesis of a number of linear and star block copolymers where at least one block consists of a polymacromonomer (molecular brush). The key to this general technique is the use of styrene-tipped macromonomers, which polymerize in a manner similar to styrene monomer. By this means well-defined styrenic macromonomers of polyisoprene, PI (sMMI), polybutadiene, PB (sMMB), and poly(styrene-b-isoprene), PSI (sMMSI), have been prepared by selective reaction of PILi, PBLi, and PSILi with the chlorine of 4-(chlorodimethylsilyl)styrene. These macromonomers and conventional monomers (styrene, isoprene, and butadiene) were homopolymerized or block copolymerized, by anionic polymerization high-vacuum techniques, to synthesize the following structures: PsMM-b-PM, PS-b-PsMM-b-PM, and PsMM1-b-PsMM2 where PsMM is PsMMI or PsMMB and PM is PS, PI, or PB. Furthermore, by utilizing the chlorosilane method, star polymers of the (PSMPsMMB) and (PsMMI-e-PDa type were synthesized. Attempts to prepare A ₃ and A ₄ star polymers with polymacromonomer arms were not entirely successful. All materials were characterized by size exclusion chromatography (SEC) with DRI and UV detectors, SEC with two-angle-laser-light- scattering detector (SEC/TALLS), and NMR spectroscopy. It was concluded that macromonomers can be used much like the conventional monomers under appropriate experimental conditions.