Photoinitiated polymerization of styrene from self-assembled monolayers on gold

We report the synthesis of grafted polystyrene (PS) films on gold via a surface-initiated polymerization strategy. The polymerization proceeded by a "grafted-from" strategy in which the polystyrene grew by free-radical polymerization from a surface-bound photoinitiator. These experiments exploited the spontaneous formation of alkanethiolate monolayers on gold to immobilize the alkylthiol photoinitiator to the gold substrate. The polymerization was initiated by irradiation with UV light (lambda = 300 nm) and resulted in the formation of a PS film. This film was found to be 25-30 nm thick by contact-mode AFM and ellipsometry. Water contact angles, X-ray photoelectron spectroscopy, and reflection-absorption infrared spectroscopy confirmed the monolayer formation and the presence of polystyrene, and all data was consistent with a grafted polymer film.