Moderating the reactivity of living anionic poly(ferrocenyldimethylsilane) with a diphenylethylene chain end:: Synthesis and characterization of polystyrene-polyferrocenylsilane graft copolymers

The synthesis and characterization of poly(styrene-g-ferrocenyldimethylsilane), the first organic-organometallic graft copolymer, are reported. This was permitted by the discovery that 1,1diphenylethylene (DPE) can effectively cap the living anionic polyferrocenylsilane generated by the ringopening polymerization (ROP) of the dimethyl-substituted [1]ferrocenophane 1 using n-BuLi as the initiator. The resultant living DPE-capped polymer was then reacted with the chloromethyl functionalities of poly(styrene-co-chloromethylstyrene) (PS-co-PCMS) (3) to afford the polystyrene-polyferrocenylsilane graft copolymers 5a and 5b. These graft copolymers were then analyzed using differential scanning calorimetry and wide-angle X-ray scattering which indicated that the materials are essentially amorphous, with at most a very low degree of crystallinity. Cyclic voltammetry of 5b in CH2Cl2 showed a well-resolved wave voltammogram with a redox coupling DeltaE of ca. 0.23 V, characteristic of the presence of significant Fe --- Fe interactions in the grafted organometallic side chains. Polymer 5b was also characterized by thermogravimetric analysis which indicated that the material is thermally stable to weight loss up to ca. 300 degreesC.