Cleaning and Functionalization of Polymer Surfaces and Nanoscale Carbon Fillers by UV/Ozone Treatment: A Review

Dry oxidizing methods have been widely used to modify surface properties of polymer and ceramic substrates. Compared to other dry oxidizing methods, ultraviolet light/ozone (UV/O-3) treatment has hitherto attracted less attention, mainly due to relatively weak oxidizing power. With optimized processing conditions, however, UV/O-3 treatment can be better capable of offering desired effects associated with appropriate surface modifications. Incorporation of nanoscale reinforcements, e. g., carbon nanotubes (CNTs) and graphite, into a polymer matrix creates a new class of composites that possess unique mechanical and functional capabilities. A proper surface treatment is critical to dispersing the reinforcements in the matrix, hence to provide adequate adhesion between the reinforcements and the matrix. In this article, a review is provided on the underlying mechanisms of and the advantages arising from UV/O-3 treatment of polymer substrates and nanoscale carbon materials. Special focus is placed on the relationship between the changes in chemical composition, morphology, functional groups of the treated surface and the corresponding improvements in adhesion and wettability of the substrate, dispersion of nano-reinforcements, as well as the properties of the nanocomposites made therefrom.