Study of wettability and optical transparency of pet polymer modified by plasma immersion techniques

Abstract

Polymers substrates have several distinct advantages, such as ruggedness, robustness, ultra-lightness, conformability, and impact resistance over glass substrates for optical applications. However, it is required high transparency, proper surface roughness, low gas permeability and high transparent electrode conductivity of the plastic substrate for commercial applications. In this work was analyzed the surface morphology of polymer samples modified by plasma immersion techniques. Polyethylene Terephthalate (PET) polymers were treated by different RF plasma immersion modes (at low and high energy ion implantation) and discharge conditions. Sulfur hexafluoride (SF6) and nitrogen (N2) gases were employed as a source of fluorine and inert plasma, respectively. Wettability surface shows that, it is possible to reach either high or low contact angle values, (10o < ? < 130o), depending on the plasma technique and gas employed. The surface morphology was measured with atomic operating on air. Both 10 µm × 10 µm and 1 µm × 1 µm images were acquired and the surface roughness was characterized in terms of the root mean square roughness, Rz, for both imaged areas. In general, the smoothness of PET was maintained for some plasma treatments. Optical Transmittance, T (?), was performed using a UV-Vis-NIR spectrometer ranging from 190 nm to 3300 nm. The results show that the low energy ion implantation is more efficient to promote the loss of T (?) at visible light, making the PET surface hydrophilic, even in fluorine plasmas. The treatments were satisfactory, daring to maintain, or even, to increase the PET transparency at visible light in restrict conditions.