Studies of the end-capping of living anionic poly(ferrocenyldimethylsilane) with 1,1-diphenylethylene

The efficiency of capping poly(ferrocenyldimethylsilane) (PFDMS) with 1,1-diphenylethylene (DPE) at room temperature and at 50 °C is reported. The capping of living anionic PFDMS chains was investigated by synthesizing short PFDMS oligomers of 10 repeat monomer units for which the end groups can be probed by 1H NMR. DPE is known to mediate the reactivity of the PFDMS, permitting the synthesis of block copolymers unobtainable by direct, sequential, living anionic polymerization such as poly(ferrocenyldimethylsilane)-block-poly(methylmethacrylate) (PFDMS-b-PMMA) and poly(ferrocenyldimethylsilane)-block-poly(2-vinylpyridine) (PFDMS-b-P2VP). However, at room temperature addition of the DPE is slow. We report that carrying out the capping of living PFDMS chains at elevated temperatures (50 °C) avoids the need to use a second reagent to facilitate the addition of DPE, or follow more complex synthetic routes.