UV assisted surface modification of polystyrene in the presence of trialkylsilanes

Abstract

A process for the photochemical modification of polystyrene (PS) surfaces employing organosilane compounds has been developed. Polystyrene was irradiated in presence of trialkylsilanes [ethyldimethylsilane (EDMS), trimethylsilane (TrMS)]. UV irradiation was carried out with a medium pressure (MP) Hg lamp and a 193 nm ArF* excimer laser. FT-IR and X-ray photoelectron spectroscopy (XPS) evidenced that after irradiation alkylsilyl groups were covalently bond to the polymer surface. Contact angle measurements proved a significant lowering in surface energy of polystyrene as a result of the photomodification process. When EDMS was used as photoreactive reagent, the introduction of Si-H groups onto the polymer surface was also found. The introduction of Si-H bonds onto polymer surfaces provides new possibilities for further surface functionalization. Atomic force microscopy (AFM) showed that Hg lamp irradiation does not exert significant changes in surface topography, while 193 nm excimer laser irradiation leads to surface corrugation. Summing up, it is demonstrated that organosilanes can be employed in UV reactions to attach silyl and also Si-H groups onto polystyrene surfaces. Possible reaction mechanisms are discussed. © 2005 WILEY VCH Verlag GmbH & Co. KGaA, Weinheim.