Richard R. Thomas

Chemical and physical modification of fluoropolymer surfaces for adhesion enhancement: a review

—The primary goal of surface modification of fluoropolymers is to improve adhesion to these low surface energy materials. Both classical methods and newer processes have been used as a means to this end. Various methods of modifying fluoropolymer surfaces include wet chemical etching, electrochemical reduction, grafting, application and removal of metals, ion and electron beam techniques, and plasma modification. In addition to the modification procedure, it is necessary to evaluate the effectiveness of the chosen method by subsequent analysis of the modified surface. Physical analytical methods include contact angle and wettability measurements, lap shear and composite tensile shear strengths, peel strengths, and surface topographical determinations. Chemical analyses used include infrared, Raman, Rutherford backscattering, ultraviolet-visible, wide angle X-ray scattering, X-ray fluorescence, and X-ray photoelectron spectroscopies as well as thermal desorption mass spectrometry. Each of the modification ...

Characterization of a Surface Chemically-Modified Polyimide

The polyimide, PMDA-ODA, has been surface (sub-surface) modified by base hydrolysis followed by protonation to leave a thin film of polyamic acid over a fully cured polyimide. The modified polyimide is characterized, in this study, by a variety of techniques including X-ray photoelectron spectroscopy, capacity (titratable amic acid groups/volume of modified polyimide) and contact angle measurements as a function of pH. XPS data clearly showed the formation of the Pd 2 +-carboxylic acid complex on the modified polyimide. Contact angle data, for various pH water, gathered on the modified polyimide, indicated the presence of carboxylic acid groups which ionize and are more hydrophilic when the pH of the probe liquid was greater than 7.