Methane/Nitrogen Mixture Plasma Assisted Surface Modification of Polymeric Materials

The aim of this study is to examine methane (CH4)/nitrogen (N-2) gas mixture plasma surface modification for various polymers including in polytetrafluoroethylene (PTFE), polystyrene (PS), polycarbonate (PC), and high-density polyethylene (HDPE). The static wetting properties of methane (CH4)/nitrogen(N-2) plasma deposited films on conventional polymers were investigated using the sessile droplet method. The change of hydrophilicity and surface free energy was monitored by static contact angle measurement. The static contact angle is an excellent indication of the change in surface state properties from plasma surface modification. A new quick image-capturing device enables static contact angle measurement 2 to 4 seconds after contact with the polymeric surface. Significant increases in the surface energies of PTFE, PS, PC, and HDPE by CH4/N-2 mixture gas plasma treatments were observed. The experimental results show the critical position of chemical species in the interaction between CH4/N-2 mixture gas plasma and the polymeric substrate, which can be controlled by surface modification to tailor the hydrophilicity of the polymers.