Nature of radical reactivity of organic plasma-exposed glass surface studied by the electron spin resonance spin-trapping technique
In order to investigate the nature of radical ractivity of a plasma-exposed glass surface, we have carried out a number of reactions for phenyl-N-t-butylnitrone (PBN) spin-adduct formation in various organic plasma-exposed glass ampoules. Certain plasma-exposed glass surfaces where an ultrathin film was deposited afforded the PBN spin adduct in such reactions. Spin-adduct formation continued to occur for a long period of time if an appropriate solvent was chosen as an activator, demonstrating that such a glass surface can undergo a constant slow release of radical species. A kinetic study indicated that the rate-determining step for the formation of the spin adduct is the stage when an active radical species is leached out of the ultrathin film. Thus the mechanism by which the ultrathin film immobilizes the active radical species and permits its slow release is ascribed to the presence of weakened σ-bonds in the film and their facile bond fission by physicomechanical action of the solvents used.