Degradation of fluorine-containing organic thin films and organohalides mediated by ionizing radiation: Nitrogen-based surface modification of polymers and metallization of nitrogen-containing polymers.

摘要

The surface modification of organic thin films and polymers has been studied using X-rays, electrons, ions, excited neutrals and metal atoms (metallization). The resulting chemical modification within the surface region has been studied to better understand the role of individual reactive species with the organic interfaces. Similarly, the role of electrons in organohalide remediation has been studied to better understand the remediation process occurring in organohalide/ice films.; During the initial period of X-ray irradiation of semi-fluorinated self-assembled monolayers (SAMs), electron-stimulated C-F, C-C and S-X (X = copper or gold substrate) bond breaking events are responsible for the changes in the chemical composition of the SAM. Irradiation-induced changes to the film's chemical and structural properties, that included the chemical transformation of a fraction of the initial thiolate species, were most pronounced in these initial stages of irradiation, prior to the development of a highly cross-linked carbonaceous overlayer. The mechanism of the carbon-fluorine bond breaking within the film has been found to be consistent with a series of single C-F bond breaking events.; The surface reactions of reactive neutral nitrogen species and nitrogen ions with polyethylene have also been studied. Neutral nitrogen species, generated using a modified nitrogen plasma, resulted in the incorporation of predominantly imine groups. Nitrogen ion bombardment yielded amine groups as the dominate species.; The reactivity of vapor-deposited metal atoms with nylon 6, nitrogen ion implanted polyethylene and a nitrile-terminated SAM have also been studied using in situ X-ray Photoelectron Spectroscopy. Iron deposition resulted in the formation of iron-nitrogen linkages for all systems studied and iron-oxygen linkages in the case of nylon 6. Similarly, Nickel deposition resulted in nickel-nitrogen linkages for all the systems studied, however it did not react with the oxygen. Copper deposition resulted in the formation of copper-nitrogen linkages on nylon 6, but was unreactive with all other systems studied. Gold was unreactive on all of the substrates studied. The relative reactivity of different polymer functional groups has been rationalized on the basis of their respective bond strengths while metal reactivity trends are correlated with the strength of new metal-oxygen and metal-nitrogen bonds that can form during metallization.; The electron-stimulated chemical reactions within carbon tetrachloride/water(ice) films produced CO₂, CO and HCl as the final neutral reaction products in the degradation of CCl₄, while COCl₂ and C₂ Cl₄ were produced as reactive intermediates. The CCl ₄ concentration effects on the film were shown to vary the partitioning of products and intermediates within the film but did not induce new species production. A reaction mechanism is postulated based on the reactivity of the trichloromethyl radical and the dichlorocarbene intermediates.