VUV processing of polymers: Surface modification and deposition of organic thin films

N-rich organic surfaces have been obtained by means of vacuum ultraviolet (VUV) processing, via the functionalization of low-density polyethylene (LDPE) surfaces and also by polymerization of hydrocarbons (CH4 and C2H4) mixed with ammonia (NH3). The fundamental mechanisms involved in grafting reactions, as well as in the polymerization of these binary mixtures are discussed as a function of wavelength, λ, of the VUV sources. The surface compositions and deposition rates are characterized by X-ray photoelectron spectroscopy (XPS) and by UV–vis spectroscopic ellipsometry, respectively. We show that photochemical reactions can be optimized by judiciously selecting λ of the VUV source, so that maximum absorption and photo-dissociation can be achieved.