Little information has been published concerning the interaction of gold with polymers. In the context of this lack of information, we decided to investigate the effect of Ar plasma treatment on the surface properties of poly(ethylene terephthalate) (PET) in order to examine its possible application for metal‐polymer adhesion improvement. The plasma treatment leads to an immediate increase of the PET's surface wettability, which however significantly depends on the sample aging, more specifically on the time elapsed after the treatment. X‐ray photoelectron spectroscopy (XPS) measurements revealed that the oxygen concentration in the surface‐near layers increases as a result of the treatment, but that it also changes with time for the samples in contact with the atmosphere, probably as a result of polar group rearrangements. Plasma initiated ablation and Au sputtering increases the surface roughness. The nanoindenter measurements revealed that the treatment increases the microhardness of treated PET. Contrary to hardness, the elastic modulus decreases. Scratch tests showed that the deformation of samples consisting of Au coatings deposited on both pristine and treated PET was elastic rather than plastic. We conclude from the nanoindenter data that the plasma modification does not affect the adhesion of gold on PET, but the X‐ray diffractometry (XRD) analysis showed that the Au film deposited on the as‐treated PET, and on PET aged for 14 d are the most stable.magnified image
Polyethyleneterephtalate (PET) and polytetrafluorethylene (PTFE) foils were modified by plasma discharge. The effect of plasma modification on polymer surface wettability and on properties of gold coatings were studied as a function of time from plasma exposure (aging time) and polymer substrate temperature. Thickness, sheet resistance, and surface topology of gold layers were studied. Aging of the plasmaexposed samples is accompanied by increase in contact angle, which is explained by rearrangement of the polymer segments in the polymer surface monolayer, and a decrease in the concentration of polar groups. The aging also leads to a decline in surface roughness R a measured by atomic force microscopy (AFM). Under deposition conditions, comparable thicknesses of deposited Au layers were prepared on pristine PET and plasma-treated PET and PTFE samples. The thinnest Au layers were evaporated onto pristine PTFE. The sheet resistance decreases with increasing thickness of Au layer. Plasma treatment leads to an increase of PTFE surface roughness, which becomes even more pronounced after Au deposition. A higher roughness shows that the PET samples are deposited with the Au layer at temperatures above the glassy transition temperature T g .
High density polyethylene (PE) was modified by argon plasma discharge and then coated with 50 nm thick gold layer. Surface morphology of as-modified PE samples and samples coated with Au was studied using atomic force microscopy technique. The surface polarity was characterized by contact angles measured by standard goniometry. A nanoindenter was used to examine the sample's mechanical properties (hardness, elasticity modulus, scratch behavior). The Au layers were characterized using X-ray diffraction. The plasma modification of PE leads to a strong decrease of the water contact angle, which further depends on the time elapsed after the plasma treatment.
Because of plasma-initiated ablation, a lamellar arrangement of PE polymeric chains becomes apparent on the plasma-treated samples. The roughness of as-modified PE decreases as a result of Au deposition. Plasma treatment increases PE microhardness but after subsequent Au deposition, both microhardness and elastic modulus decline.Scratch tests showed that while on Au-coated pristine PE samples mainly elastic deformation was observed, on plasma-treated and subsequently Au-coated samples plastic deformation and mechanical deterioration played a significant role. According to the XRD analysis, Au film deposited on the modified PE should be the most stable.
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