The surface properties modification of polyethylene by enhanced glow discharge plasma immersion ion implantation

Polymers are frequently surface modified to achieve special surface characteristics such as antibacterial properties, wear resistance, anti-oxidation, wetting property and good appearance [1]. The application of plasma immersion ion implantation (PIII) to polymers is of practical interest as PIII offers advantages such as low costs, small instrument footprint, large area, and conformal processing capability [2,3]. In addition, PIII does not alter the appearance of polymers such as polyethylene (PE) [4]. Oxygen is an element which can improve the polyethylene wetting property by plasma immersion ion implantation. However, the insulating nature of most polymers usually leads to nonuniformity plasma implantation and the surface properties can be adversely impacted. As an alternative technique to conventional plasma immersion ion implantation (PIII), enhanced glow discharge plasma immersion ion implantation (EGD-PIII) does not require external plasma sources [5-7]. In our previous research, the electron density is quite uniform approaching the negatively biased substrate. A region with a uniform incident dose can be achieved using a pulse width of 40 μs and it becomes smaller with expanding plasma sheaths according to numerical simulation. Furthermore, the low energy component is smaller and the retained dose increases in EGD-PIII compared with traditional PIII [8]. Hence, the implantation efficacy of EGD-PIII is better than that of PIII, especially from the perspective of impact energy uniformity. In this work, the oxygen implanted into polyethylene is conducted by EGD-PIII. Two samples were prepared by conventional PIII and EGD-PIII for comparison. The wetting property is determined by contact angle measurement. The depth profile of oxygen is acquired by x-ray photoelectron spectroscopy (XPS) to investigate the uniformity of retained dose.