Title

Physical and chemical treatments of adhesive metal-polymer/biopolymer systems

Date of Completion

January 1993

Keywords

Chemistry, Analytical|Chemistry, Polymer|Chemistry, Radiation

Degree

Ph.D.

Abstract

Adhesion is very important in a number of technological applications. The development of new adhesives and modification of substrate surfaces are major areas of research. Bioadhesives are of increasing interest in microsurgery. The interaction of a bioadhesive and implantation materials is of paramount significance. Adhesion is determined by the top few monolayers of surfaces. Hence, the surface modification is critical for successful adhesion. In this thesis, studies of orientation of a unique bioadhesive on implantation metal surfaces, microwave plasma modification and ion irradiation of polymer surfaces and metallization of polymer surfaces are presented.^ Molecular organization of mussel adhesive protein on the titanium and iron foil surfaces was determined. Angle resolved X-ray photoelectron spectroscopy was employed to determine the orientation of adhesive protein on the metal substrates. The orientation of the polymer was such that the majority of the nitrogen atoms face away from the metal/adhesive interphase on a titanium substrate and towards the metal/adhesive interphase on an iron substrate.^ Surface modification of tetrafluoroethylene and perfluoroalkoxyvinyl ether copolymer (PFA) and poly(ethylene terephthalate) (PET) surfaces was induced by argon, nitrogen, air, carbon monoxide, hydrogen and nitrogen/hydrogen plasmas using microwave generator. The surfaces were analyzed by X-ray photoelectron spectroscopy, fast atom bombardment mass spectroscopy and scanning electron microscopy. The surfaces were modified extensively involving peeling, etching, cross-linking and generation of new functional groups. Increase of plasma power increased the extent of modification. Downstream plasma treatment was determined to be more effective compared to upstream plasma treatment.^ Irradiation of PFA and PET surfaces with argon and nitrogen ions was explored. Chemical alteration similar to argon and nitrogen plasma treatments was observed. The study showed that the extent of surface modification is determined by irradiation time, ion beam energy and the type of ions employed. Comparison of plasma treatments and ion irradiation showed that ions rather than ultraviolet radiation induced the surface modification observed in plasma treatments.^ Plasma enhanced metallo-organic chemical vapor deposition (PEMOCVD) was used to deposit metal oxides on polytetrafluoroethylene (PTFE) surfaces. Cobalt, tungsten and molybdenum carbonyls were used as organometallic precursors. Argon/hydrogen plasmas resulted in the formation of metallic species. Metal oxide films deposited by PEMOCVD on PTFE enhanced the adhesion of thermally deposited copper films. ^

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