Application of extremely non-equilibrium plasmas in the processing of nano and biomedical materials

Abstract

Some applications of extremely non-equilibrium oxygen plasma for tailoring the surface properties of organic as well as inorganic materials are presented. Plasma of low or moderate ionization fraction and very high dissociation fraction is created by high frequency electrodeless discharges created in chambers made from a material of low recombination coefficient. The O atom density often exceeds 10 21 m −3 which allows for rapid functionalization of carbon-containing materials. Surface saturation with polar oxygen-rich groups is achieved in a fraction of a second and further exposure leads to etching. The etching is often non-uniform and results in nano-structuring of surface morphology. A combination of rich morphology and saturation with polar functional groups allows for a super-hydrophilic character of originally hydrophobic materials. Polymer composites are etched selectively so the polymer component is removed from the sample surface, leading to modified surface properties. Furthermore, such a treatment allows for distinguishing the distribution and orientation of fillers inside the polymer matrix. The exposure of inorganic materials to non-equilibrium oxygen plasma causes one-dimensional growth of metal oxide nanoparticles, thus representing a unique technique for the rapid catalyser-free growth of nanowires.

Surface Functionalization of Polyethylene Granules by Treatment with Low-Pressure Air Plasma

“…40 cm × 40 cm × 40 cm was made from aluminum. The native oxide layer forms on the aluminum surface, leading to rather inert properties against different plasmas of molecular gases, since the coefficient for heterogeneous surface recombination is low for various atoms [ 20 ]. The chamber had the volume of about 60 L and was pumped with a Roots pump backed by a two-stage rotary pump through a high efficiency particulate air (HEPA) filter, a butterfly valve, and bellows.…”

Modification of Physico-Chemical Properties of Acryl-Coated Polypropylene Foils for Food Packaging by Reactive Particles from Oxygen Plasma

“…Figure 3 represents the required treatment time for the fluences of 1 × 10 22 and 1 × 10 23 m –2 . From this figure, one can conclude that the required treatment time for receiving the fluence of 1 × 10 22 m –2 is only 6 ms at the atom density of 1 × 10 22 m –3 , which is typical for the extremely reactive oxygen plasma [ 39 ]. Such a short treatment time is achievable only when using pulsed discharges.…”

Atomic oxygen and hydrogen loss coefficient on functionalized polyethylene terephthalate, polystyrene, and polytetrafluoroethylene polymers

“…Different materials exhibit different ability for binding atoms onto their surfaces; therefore, the recombination coefficient depends on the type of a material. The literature survey indicates that the materials could be grouped to inert (recombination coefficient below 0.01) and catalytic (above 0.01, typically around 0.1) . The list of the inert materials includes some glasses, ceramics, and metals that form very stable oxides, like alumina.…”