An Optimized Two-Step Nitrogen-Based Plasma Treatment Procedure under Atmospheric-Pressure Condition and its Surface Amination Mechanism

Abstract

Atmospheric pressure nitrogen-based dielectric barrier discharge (DBD) jet with two-step plasma treatment procedure has been verified to be very effective in facilitating nitrogen-containing group incorporation on Polylactide (PLA) surface. It includes: 1) pretreatment plasma treatment by a nitrogen discharge with a trace amount of oxygen, and 2) ammonia plasma treatment by a nitrogen discharge with a small amount of ammonia. In this study, the optimized operation condition of two-step plasma procedure is investigated under different concentrations of added gases (0-1% oxygen; 0-10% ammonia). XPS analysis shows that approximate to 0.19 of N/C ratio can be achieved by means of the optimized two-step plasma procedures. Furthermore, a surface amination mechanism is proposed based on the observations of Optical Emission Spectra (OES), Atomic Force Microscope (AFM), and X-ray Photoelectron Spectra (XPS) analyses.