Effects of aging on radiofrequency-sputtered polyethylene film

The effects of aging on polyethylene film deposited by radiofrequency sputt ering on a quartz crystal microbalance were examined by measuring its reson ance frequency and conductance, and by measuring the contact angle of the f ilm to distilled water. The film sputtering was observed using in situ opti cal emission spectroscopy. The fabricated film was observed using atomic fo rce microscopy, and analyzed using Fourier transform-infrared and electron spin-resonance-spectroscopies. The longer the film was exposed to air, its weight increased and the film became softer. Increase in hydrophilicity of the surface, decrease in spin concentration in the film, and enrichment of the oxygenated moieties in the film were observed. These indicate that the film structure is reconstructed by the reactions between radical sites in t he film and reactive species in the air, such as oxygen and water, and by t he movement of hydrophilic moieties inside the film towards the surface. Wh en stored in vacuum, the film hardened and oxidation slowered. (C) 1999 Joh n Wiley & Sons, Inc.