Plasma parameters effects on the properties, aging and stability behaviors of allylamine plasma coated ultra-high molecular weight polyethylene (UHMWPE) films

In this work, a dielectric barrier discharge (DBD) operated at medium to atmospheric pressure has been used for the deposition of thin polyallylamine (PAA) films on ultra-high molecular weight polyethylene (UHMWPE) substrates. The effect of treatment time (1-5 min), discharge power (5.7-24.0 W), monomer concentration (1-2 g/h) and pressure (10-100 kPa) on the films properties, aging and stability behaviors have been investigated. The used characterization techniques are X-ray photoelectron spectroscopy, water contact angle and optical reflectance spectroscopy. In this paper, it is shown that plasma treatment time does not affect the coatings chemistry; whereas plasma power, monomer concentration and pressure control the coatings properties. It is also shown that the deposition rate of the deposited films changes with varying WIFM values. At low WIFM values, high deposition rates of up to 2 nm/s are observed. Plasma treatments were also characterized by their amino efficiency ([NH2]/[C] in %) and amino selectivity ([NH2]/[N] in %). Depending on the used parameters, these varied between 12.3% and 20% and between 71.2% and 91.1%, respectively. For the aging study, coatings that preserved most of their hydrophilicity were obtained at power <= 11.3 W, monomer concentration >= 1.5 g/h and pressure >= 50 kPa. For the stability study, coatings that showed the highest [N] (%) and lowest percentage of thickness decrease were obtained at <= 2 min, 24.0 W,1 g/h and pressure <= 50 kPa. One can therefore control the deposition rate as well as the properties, aging and stability behaviors of the deposited coating by carefully choosing the plasma parameters. (C) 2017 Elsevier B.V. All rights reserved.