Controlled Thiol-Ene Functionalization of Polyferrocenylsilane-block-Polyvinylsiloxane Copolymers

A general route for the controlled functionalization of polyferrocenylsilane-block-polyvinylsiloxane copolymers, which should be transferable to other silicone-based materials, is developed utilizing the photoinitiated thiol-ene reaction. Poly(ferrocenyldimethylsilane)(54)-block-poly(methylvinylsiloxane)(510) (PFDMS54-b-PMVS510) is synthesized via sequential living anionic polymerization and quantitatively functionalized with a range of thiols, with the aim of tuning the solubility of the resulting materials for self-assembly studies or incorporating more complex functionality for subsequent applications. When functionalization is attempted using a deficit of thiol, the photoinitiator 2,2-dimethoxy-2-phenylacetophenone, used to accelerate the radical reaction, is found to cause significant cross-linking of the polysiloxane chain. Reproducible percentage thiol-ene functionalization of the polysiloxane block can be achieved by the use of PFDMS53-b-PMVS58/PDMS444 (PDMS = polydimethylsiloxane), prepared by the copolymerization of cyclic siloxane monomers, [Me(CHCH2)SiO](3) and [Me2SiO](3), to tune the vinyl group incorporation pre-functionalization.