Polymer etching by atmospheric‐pressure plasma jet and surface micro‐discharge sources: Activation energy analysis and etching directionality

Abstract

Treatments of polymer films using either a MHz atmospheric pressure plasma jet (APPJ) or an atmospheric pressure surface micro-discharge (SMD) plasma are investigated. While the typical approach to determine relevant reactive species is to correlate surface effects with gas phase species measurement, this does not capture potential synergistic or other complex effects that may be occurring. Activation energy and directionality of the etching process can characterize what is occurring at the surface for these processes in more detail. The APPJ source shows an apparent activation energy of ∼0.18 eV at 8 mm distance and up to ∼0.34 eV at 16 mm distance for a temperature range of 20-80°C tested with thin polymer films. The APPJ source shows directional etching at 8 mm distance with less anisotropy the more distance is increased. The SMD source has an apparent activation energy of ∼0.8-0.9 eV at a distance of 3 mm. The SMD also only shows isotropic etching behavior. However the SMD surface chemistry changes significantly to less oxidation with increased temperature while the APPJ source induced modifications remain very similar with temperature change. The lower apparent activation energy of the APPJinduced etching reactions as compared with low pressure work (0.5 eV) and observation of line-of-sight contribution to etching suggests the involvement of a directional species at closer distances facilitating the etching which falls off with increasing distance. The high activation energy of the SMD suggests that species with less capability for etching is responsible compared to the APPJ and low pressure plasma. The high surface oxidation from low temperature SMD treatments shows that the surface is being oxidized but not sufficiently to reach the desorption step of the etching process.

Interaction of long‐lived reactive species from cold atmospheric pressure plasma with polymers: Role of macromolecular structure and deep modification of aromatic polymers

“…Although the etch rate is only a few nanometers per hour at room temperature, we measured higher etch rates up to approximately 1 nm/min at 70°C. This increase of the etch rate at elevated temperature has been generically observed for plasma etching of polymers in both low pressure and atmospheric pressure, and the temperature dependence of the etching reaction rate constant can be expressed as: where is the pre‐exponential factor, is the Boltzmann constant and T is the substrate temperature. The apparent activation energy is an empirically fitted parameter that represents the energy required for the etching reaction to take place.…”

Turbulence and entrainment in an atmospheric pressure dielectric barrier plasma jet

“…Atmospheric pressure plasma jets have been widely used in many healthcare and materials processing applications, ranging from etching and deposition to microbial decontamination and cancer therapy. [1][2][3][4][5] Perhaps the most widely used plasma jet configuration is based on the dielectric barrier discharge employing a noble gas such as helium or argon; typically, the gas is flushed through a dielectric capillary and subjected to an applied voltage using one or more electrodes placed inside and/or outside of the capillary. On the application of a time-varying voltage of sufficient magnitude to cause a breakdown, a discharge forms within the capillary and propagates as a fast-moving ionization wave along the noble gas channel, ultimately exiting the capillary and extending into the surrounding quiescent air.…”

“…Atmospheric pressure plasma jets have been widely used in many healthcare and materials processing applications, ranging from etching and deposition to microbial decontamination and cancer therapy . Perhaps the most widely used plasma jet configuration is based on the dielectric barrier discharge employing a noble gas such as helium or argon; typically, the gas is flushed through a dielectric capillary and subjected to an applied voltage using one or more electrodes placed inside and/or outside of the capillary.…”

Study on atmospheric air glow discharge plasma generation based on multiple potentials and aramid fabric surface modification

“…Low temperature plasma surface modification technology has broad application prospects because of its remarkable advantages such as high efficiency, low energy consumption, environmental protection, and it only acts on the surface of fibers without affecting the properties of the main stems of fibers . Furthermore, low temperature plasma generated by glow discharge is considered to be the best choice for material surface modification because of its good discharge uniformity, abundant active particles, and appropriate power density …”