Preparation of hydrophilic polymeric nanolayers attached to solid surfaces via photochemical and ATRP techniques

Three different hydroxyl functional propylene/10-undecen-1-ol (PP-OH) copolymers were attached photochemically to a photoreactive benzophenone derivative that was bound to SiO₂ surfaces via a silane anchor. As a result of the photochemical reaction, thin layers of the PP-OH polymers were covalently bound to the surface. The thickness of the layers was a function of the molecular weight of the polymer. Poly(2-hydroxyethymethacrylate) (PHEMA) nanolayers were successfully grafted onto the PP-OH-modified silicon wafers (PP-OHMSW) via surface-initiated atom-transfer radical polymerization (ATRP) in aqueous media at ambient temperature. Kinetic studies revealed an increase in thickness with reaction time, indicating that the polymerization process has some "living" character. Contact angle measurements showed a reduction in the water contact angles of the resulting PP-OHMSW-PHEMAs, indicating a more hydrophilic surface tension state. The coupling of ATRP initiator to the hydroxyl groups on the PP-OH polymers, the surface-initiated ATRP, and the grafting of PHEMA onto the PP-OHMSW were confirmed by Fourier transform infrared spectroscopy (FT-IR). The grafted polymeric layers provide a platform for further surface modification through the functionalization of the hydroxyl groups of the PHEMA polymers.