Low-density polyethylene films treated by an atmospheric Ar-O sub(2) post-discharge: functionalization, etching, degradation and partial recovery of the native wettability state

• Published in: Journal of physics. D, Applied physics Applied physics, 2014-02, Vol.47 (6), p.1-12
• Main Authors: Rich, S Abou, Dufour, T, Leroy, P, Nittier, L, Pireaux, J J, Reniers, F
• Format: Article
• Language: English
• Subjects: Argon; Atmospherics; Contact angle; Etching; Flow rate; Polyethylenes; Recovery; Wettability
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/47/6/065203

To optimize the adhesion of layers presenting strong barrier properties on low-density polyethylene (LDPE) surfaces, we investigated the influence of argon and argon-oxygen atmospheric pressure post-discharges. This study was performed using x-ray photoelectron spectroscopy, atomic force microscopy, optical emission spectroscopy (OES) and dynamic water contact angle (WCA) measurements. An ageing study is also presented to evidence the stability of the treated surfaces over 60 days. After 60 days of storage, we showed that whatever the O[sub 2] flow rate, the treated films registered a loss of their hydrophilic state since their WCA increased towards a common threshold of 800. This `hydrophobic recovery' effect was mostly attributed to the reorientation of induced polar chemical groups into the bulk of the material. Indeed, the relative concentrations of the carbonyl and carboxyl groups at the surface decreased with the storage time and seemed to reach a plateau after 30 days.