Trialkylsilanes as reagents for the UV-induced surface modification of polybutadiene

A photochemical process for the modification of polymer surfaces using organosilane compounds has been developed. The process is based upon the UV irradiation of polybutadiene in the presence of liquid ethyldimethylsilane (C2H5)(CH3)2Si-H and gaseous trimethylsilane (CH3)3Si-H. UV irradiation was carried out with a medium pressure Hg lamp and a 193 nm ArF* excimer laser. The modified polymer surfaces were investigated by infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), contact angle measurements and atomic force microscopy (AFM). It is found that the photoassisted surface modification with trialkylsilanes leads to the introduction of trialkylsilyl groups onto the surface of the target polymer. From quantitative XPS data the composition of the modified polymer suface (C, O and Si) was determined. The surface modification with trialkylsilanes results in a significant lowering of surface tension γ of polybutadiene. The silane/UV process was found to be very sensitive to small amounts of oxygen in the process gas. Summing up, it is demonstrated that UV irradiation in the presence of gaseous silane compounds is a convenient way to introduce organosilicon groups onto the surface of technical polymers.