Plasma Reactions
Plasmas are very reactive gases consisting of excited or ionized atoms and molecules.
"In non-thermal equilibrium plasmas, free electrons are very hot,with temperatures at many thousands of Kelvin (K),whileneutral and ionic species remain cool. Because the free electrons have almost negligible mass, the total system heat content is low and the plasma operates close to room temperature,thus allowing the processing of temperature-sensitive materials, such as plastics or polymers, without imposing a damaging thermal burden. The hot electrons create, through high-energy collisions, a rich source of radicals and excited and/or unstable species with a high chemical potential energy capable of profound chemical and physical reactivity. This combination of low-temperature operation plus high reactivity makes non-thermal equilibrium plasma technologically important and a very powerful tool for manufacturing and material processing,as it is capable of achieving processes that, if achievable at all without plasma, would require very high temperatures or noxious and aggressive chemicals."
(Bunce, Parbhoo and Chevalier, US Patent 7,758,928, 7/20/2010)
Recent US Patents
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7/20/2010
7,758,928
Functionalisation of particles
Bunce, Parbhoo and Chevalier of Dow Corning have developed a method of treating powders with a functionalizing reagent with a neutral, excited atmospheric pressure plasma in a fluidized bed. The plasma is formed by glow discharge or dielectric barrier discharge. The powders may be metal, ceramic,or organic polymers. (RDC 9/16/2010)
Recent Journal Articles
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9/17/2010
Poly(ethylene oxide)-like Plasma Polymers Produced by Plasma-Assisted Vacuum Evaporation
(pages 445–458)Plasma Processes and Polymers 7 #6 (2010)
Choukourov et al showed that thermal decomposition of PEO under vacuum in combination with a glow discharge formed PEO-like plasma polymer films. Plasma-assisted vacuum evaporation leads to crosslinking within the films at the expense of the ether structure. (RDC 11/2/2010)
Reaction Chemistry of 1,4-Benzopyrone Derivates in Non-Equilibrium Low-Temperature Plasmas
(pages 466–473)Plasma Processes and Polymers 7 #6 (2010)
Grzegorzewsk showed that 1,4-Benzopyrone derivates exposed to different cold gas discharges reveal a structure-dependent degradation. Contact-angle measurements indicate a strong surface oxidation is Independent of the plasma source. (RDC 11/2/2010)
Surface Activation of Poly(methyl methacrylate) via Remote Atmospheric Pressure Plasma
(pages 482–493)Plasma Processes and Polymers 7 #6 (2010)
Gonzalez et al showed that treating PMMA surfaces with an atmospheric pressure oxygen/helium plasma decreased the surface methyl groups and increased the surface carboxyl groups leading to a 35 degree decrease in water contact angle and a ten-fold increase in bond strength. Activated oxygen atoms in the plasma oxidized the surface. (RDC 11/2/2010)
Determination of OH Groups at Plasma Oxidised Poly(propylene) by TFAA Chemical Derivatisation XPS: An Inter-laboratory Comparison
(pages 494–503)Plasma Processes and Polymers 7 #6 (2010)
Gross et al showed by an inter-laboratory study that agreement between laboratories on the fraction of C-OH groups in a plasma oxidized polypropylene sample is low. (RDC 11/2/2010)
Formation and Distribution of Silver Nanoparticles in a Functional Plasma Polymer Matrix and Related Ag+ Release Properties
(pages 619–625)Plasma Processes and Polymers 7 #7 (2010)
Körner et al produced polymer coatings with embedded silver particles by plasma polymerization of a carbon dioxide ethylene mixture using a silver electrode. Increasing the power, increased the silver content. (RDC 11/2/2010)