Sustainable atmospheric-pressure plasma treatment of cellulose triacetate (CTA) films for electronics

Abstract

Surface treatments of cellulose triacetate (CTA) films via atmospheric pressure plasmas containing helium and either O2 or C3F6 as plasma reactive gas were performed to study their effects on moisture barrier, transmittance, thermal, surface chemistry, and morphological properties. Plasma treated CTA films were characterized using X-ray photoelectron spectroscopy (XPS), attenuated total reflectance-Fourier transform infrared spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscopy analytical techniques. Both surface chemical and morphological changes were correlated with water vapor transmission rates (WVTRs) and contact angle measurements. XPS spectra showed that the relative chemical composition of the C 1s spectra after O2 plasma treatments exhibits an increase in the relative amount of C—C bonds, which may be due to a change in surface cross-linking. ToF-SIMS spectra showed the depth of treatment of atmospheric plasma treatment of CTA films at about 100 nm. The WVTR of the CTA film was reduced up to 20% after sustainable atmospheric O2/helium plasma, while no significant changes were observed in light transmittance. Thus, the use of sustainable atmospheric plasmas to enhance moisture barrier while maintaining other critical properties such as light transmittance, thermal stability, and morphology of a CTA film could provide significant benefits to the electronics industry.