Degree of Wettability and Aging of PVC and PET Polymers Treated by Plasma Immersion or Deposition

Abstract

The wettability, aging characteristics, and optical transmittance in the visible region following Plasma Immersion (PI) or Plasma Immersion Ion Implantation (PIII) treatment of polymers were studied. In addition, structural and chemical modifications of the polymers were examined. The polymers investigated were white Polyvinyl chloride (PVC) and Polyethylene terephthalate (PET). Initially, plasmas of nitrogen (N₂) were employed, aiming to produce hydrophilic surfaces. In contrast, sulfur hexafluoride (SF₆) plasma treatments produce high surface fluorination, which tends to increase hydrophobicity. Isopropyl alcohol (IPA) was mixed with SF₆ or N₂ to deposit a series of organic films. Aging effects over 30 days on the contact angle, q, were measured for the polymer surfaces. Conventional plasma immersion (PI) tended to decrease of θ for N₂ plasma treatments, with or without IPA, and to increase θ values ​​for samples immersed in IPA/SF₆ plasma.  The highest value of θ was 140º for IPA/SF₆ plasma treatments, while the smallest θ was 20º for N₂ or IPA/N₂ treatments. There was an ideal condition under which θ was stable upon aging. The results obtained suggest the developed treatment enables the preparation of polymers with distinct wettability properties depending of the nature of the plasma with overall reasonable aging stability. Moreover, the opaque character of these materials makes them interesting for the production of bags, boxes, bottles, food packaging, among others.