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Plasma and Technology
- 1. Plasma and Technology Farzad Rezaei 01/01/2017
- 3. Plasma – the 4th State of Matter
- 4. 4th State of Matter? Conductive Collective Response Magnetically Active
- 6. E E 1) 2) Electron Avalanche ≡ Electron Multiplication Electron Impact Ionization Electron-Neutral Collision Cathode(-) Anode(+) Ionized Gas (Plasma) http://en.wikipedia.org/wiki/John_Sealy_Townsend#media viewer/ John Sealy Townsend (1868-1957) http://www.arjenboogaard.nl/Irving%20Langmuir.html Irving Langmuir (1881-1957) Gases Under Electric Discharge
- 7. Chemistry in Plasma Electron-impact ionization: e + N -> N+ + 2e Electron-impact excitation e + N -> N* + e De-excitation by photon emission N* -> N + hν Free radical formation: e + R-R -> 2R + e
- 11. Atmospheric Pressure Plasma System For Polymer and Textile Industries
- 12. Atmospheric Pressure Plasma Lab Conveyor Plasma Chamber 30 cm Plasma lines – helium gas
- 13. 300 400 500 600 700 800 900 1000 Wavelength [nm] O O He He Plasma Color and Chemistry 300 400 500 600 700 800 900 1000 N2 (B-A) Wavelength [nm] N+ 2 N2 (C-B) 300 400 500 600 700 800 900 1000 Wavelength [nm] O O He H He OH N+ 2
- 14. Wetting Behavior
- 15. Surface Modification via Plasma Plasma
- 16. Surface Wettability 0 20 40 20 30 40 50 60 70 80 90 100 water [degrees] Plasma Dose [J cm-2 ] He He/O0.8% 2 He/N0.5% 2 Control Contact angle: 25 Contact angle: 87 Polyester film substrate
- 17. Surface Roughness Surface of control sample After exposing to the plasma
- 19. Functional Coatings Formation of free radicals: e + R-R -> 2R + e Plasma state polymerization (deposition) R + n(M=M) -> R-(M-M)n-1M-M Water and oil repellent side Polymerizable side Water or Oil Drop
- 20. Coating and Curing Textiles Spraying precursor Exposing to plasma 0 20 40 60 80 100 120 140 0 30 80 100 120 140 160 180 F6-75vF6-100vF6-50vF6-25v Theta(water)[degrees] time [s] Control sample
- 21. Wetting Behavior After Curing with Plasma
- 22. Benefits of Plasma for Textile Applications Affected area on the surface Bulk Surface Specific Process Environmentally friendly Efficient Scalable Multifunctional
- 23. THANK YOU!
Editor's Notes
- When talking about plasma, of course besides this plasma globe, the first thing come to a mind is either plasma TV or blood plasma. Except that the blood plasma is completely different than the two other examples here, indeed, these all are actually plasmas and some how their name is co-related and I will talk about it briefly in this presentation.
- The plasma that I am going to talk about today is known as the fourth state of matter. Plasmas are highly energetic gases that contain ionized particles. To be considered a totally new state of matter, this excited gas must manifest properties that no other gases posses.
- These properties include: plasma is conductive, it collectively responds to stimuli, and it is also magnetically active. Indeed, the northern light is due to interaction of plasma gas with magnetic field of the earth.
- Besides the northern light, majority of the mass of universe is composed of plasmas. Stars are in fact massive amounts of gases that are extremely hot that are in plasma state. Well, this is great, but obviously we cannot hold such extremely hot materials in our lab and industries. But we can take advantage of the properties of plasmas to make cold plasmas on the planet earth.
- Industrially, we can make plasma by exciting a gas using electric field.
- There are many other aspect of plasma that make this gas very useful material for technological applications. Here are some of the most important reaction that takes place in a plasma.
- Because of the energy level of their atoms and molecules, different gases emit light at different wavelength. This is a very useful characteristics that we can use to analyze a plasma using its optical emission.
- Besides lighting industries, plasma has been used in many different application areas. The most significant application of plasmas is in microelectronic industries. Plasmas also have been used in thin film coating, microfluidics, printing, medical and textile industries that makes plasmas a multifunctional technology.
- As I mentioned, the most significant application of plasma is in microelectronics. Plasma has been used to create patterns on silicon substrates in miniaturized scales. This micrograph shows a trench having 200 nm with and 4 micrometer depth that is created by plasma. The fact that plasma enables creation of such small features has lead to shrinkage of the size of our current computers.
- Wetting Behavior is a scientific term to describe how liquids behave in contact with solids (or vice versa).
- Plasma is a powerful tool to alter chemical and physical properties of a surface. The high energy molecules produce in the plasma can react with the target surface. The reaction of these high energy particles with the surface can lead to a surface etching and surface functionalization. The new surface have different wetting behavior.
- And here we can see this alteration of the wetting behavior. The photographs on the right show a drop of water on the surface of a polymer film before and after exposure to the plasma. We can see that after treating the surface, the water drop tend to spread on the surface compared to untreated surface. Controlling the wetting properties of a solid is particularly important for technologies such as printing and coating.
- These images are atomic force micrographs taken from a polymeric film before and after exposure to the plasma. We can clearly notice the change of surface roughness of the polymer after the plasma treatment. An increase in surface roughness provides higher surface area for interacting with liquids or solids that come into contact with the surface. This is also important for adhesion properties of the film.
- In a completely opposite direction to what I just talked about, plasma can be used to reduce the surface wettability.
- The high energy particles produced in plasma can polymerize chemicals that contain inert side chains. Fluorocarbons are of most inert chemicals that have minimum interaction with other materials including aliphatic oils and water. Treating materials such as textiles with such chemicals give them the ability of repelling water and oil.
- Here how we can do this: first we spray the textile with the inert chemical and then expose it to the plasma source. On the right we can see how the treatment changed the wetting properties of the textile. The photographs on the bottom show water droplet on an untreated fabric that overtime is absorbed to the fabric. The images on the top show that the water droplet beads up on the surface and is not absorbed by the substrate.
- This image also shows that the untreated fabric easily can be stained, on the other hand, the stained water does not wet the fabric. The far right micrograph is taken using scanning electron microscope and shows the fabric structure after coating it with plasma.
- For concluding this presentation, here are some of the advantages of using plasma for textile industries:
- For concluding this presentation, here are some of the advantages of using plasma for textile industries: