1,1-Dimethylsilacyclobutane-Mediated Living Anionic Block Copolymerization of [1]Dimethylsilaferrocenophane and Methyl Methacrylate

An efficient synthesis is described of diblock copolymers from [1]dimethylsilaferrocenophane (FS) and methyl methacrylate (MMA). First, living anionic polymerization of FS is carried out in THF. When the FS polymerization is complete, 1,1-dimethylsilacyclobutane (DMSB) and 1,1-diphenylethylene (DPE) are added in order to modify the living PFS chain ends in an appropriate way for the subsequent growth of the second block. This combination of an accelerator (DMSB) and an end-capping agent (DPE) is shown to be necessary to suppress side reactions which otherwise lead to significant quantities of PFS homopolymers. When all the PFS chain ends bear an anionic DPE end group, block copolymerization of MMA follows. Under optimum conditions, PFS-b-PMMA block copolymers can be obtained in >90% yield (in addition to