Candle soot as a template for a transparent robust superamphiphobic coating

1. Candle soot as a template for a transparent robust superamphiphobic coating By: group 18

2. Graphical abstract • Scientist have created a superamphiphobic coating using candle soot and a silica layer • This gives the surface both hydrophobic and oleophobic properties • Thermal stability: coating was able to maintain properties until 400°C • Abrasion stability: coating maintained properties until layer was less than 2μm thick www.huntsman.com

3. Introduction • Superamphiphobic- meaning a surface is both superhydrophobic and superoleophobic • Hydrophobic- material is resistant to water • Oleophobic- material is resistant to oil • Example of a superamphiphobic coating: http://www.youtube.com/watch?v=IPM8OR6W6WE

4. Introduction • In industry, it is desirable to have hydrophobic/oleophobic surfaces. Because liquid has a low affinity for the surface, the liquid beads up, taking dirt and other particles with it. • This makes the material self-cleaning http://www.nanovere.com/nanotechnology.html

5. Introduction Examples of Hydrophobic materials Examples of Oleophobic materials Low surface energy materials • Polyethylene • Polypropylene • Nylon 10,10

6. Basic principles • When a liquid meets a surface, it meets at an angle where the liquid/vapor interface meets the solid • This is called the contact angle • Hydrophilic surfaces cause the water droplet to spread out, resulting in a smaller contact angle (0-90°) • Hydrophobic surfaces have contact angles >90° Makin' contact. (2011, 03 04). Retrieved from http://materialsgirlny.tumblr.com/post/3638362998/makin-contact

7. www.ramehart.com

8. Basic principles • Roll-off angle: angle of a surface where a drop of liquid will start to move • Point where the force of gravity overcomes the force of surface tension Bharat Bhushan, Yong Chae Jung, Natural and biomimetic artificial surfaces for superhydrophobicity, self-cleaning, low adhesion, and drag reduction, Progress in Materials Science, Volume 56, Issue 1, January 2011, Pages 1-108, ISSN 0079-6425, 10.1016/j.pmatsci.2010.04.003. (http://www.sciencedirect.com/science/article/pii/S0079642510000289)

9. Work performed • Glass slide was held above a Paraffin candle and coated in its soot • Coating causes material to be superhydrophobic • However, the soot structure is fragile

10. Work Performed • Soot was coated with a layer of silica • Using chemical vapor deposition of tetraethoxysilane and catalized by ammonia • This process makes the coating stronger

11. Work performed • The coated glass was then calcinated at 600˚C to make it transparent • Coated with semi-fluorinated silane by CVD

12. Work performed • Results show high contact angle with both water and organic liquids relative to the original surface

13. Work performed • The coating began to break down: • Thermal stability test- • Fluorosilane began to break down at 400˚C- meaning coating lost its oleophobic properities • Silica network broke down at 1000˚C • Abrasion stability test- • Sand formed cavities in the coating, however, it maintained its superamphiphobic properties until the coating was less than 2µm thick Schematic of sand abrasion test

14. Conclusion • This superamphiphobic coating is simple to make and effective against water, oil, and other hexanes • It is self cleaning because dirt and other solid particulate roll off with the liquid • It maintains its properties until 400°C • It is transparent- opening up a wide range of applications Jiang, W., Hu, H., & Zhang , Y. (2013). Publications. Retrieved from http://www.chem.queensu.ca/people/faculty/Liu/publications.html

15. Assessment of the work • Possible improvements: • The explanation of soot as the reason for the coating’s superamphiphobic properties is never thoroughly explained • The experiment lacks control over other possible influencing variables • The paper never explicitly explains what gives a material oleophobic properties www.aculon.com

16. Assessment of the work • Analysis • The paper presents a practical approach to making a superamphiphobiccoating • From their test, the coating has a large number of useful applications ranging from goggles to large scale chemical production • Further research is required before the small scale process can be converted to a large scale commercialized product • The small scale lab set up isn’t necessarily practical on an industrial scale • Cost analysis would be necessary to ensure profitability

17. Further research • Methods of cost efficient mass production • As we know, in industry, one of the most important considerations is cost. • If a company does not have a method to mass produce material at a low cost then they will not make a profit. • Research in this area would include searching for commercially available materials that also have the correct characteristics to create superamphiphobic properties

18. Further research • How to make Fluorosilane remain stabile at higher temps • As we have shown in our Work Performed, Fluorosilanebegan to break down at 400˚C- meaning coating lost its superamphibhobic properties • For our superamphiphobic material to more use,weneed to increase to temperature range in which Fluorosilaneremains stable. • Many reactions take place at temperatures higher than 400˚C. For these reactions, it is desirable for an superamphiphobic material to remain intact as a coating and not break down and become a possible impurity. http://www.chemspider.com/Chemical-Structure.10328917.html

19. Further research • Sand Abrasion • The Sand Abrasion Test showed that the superamphiphobicmaterial is inevitably susceptible to wearing away. • Research should be performed to find ways to make superamphiphobic materials more resistant to wearing. • This is important because a more robust material leads to a longer lasting coating. http://www.trl.com/services/materialstesting/abrasion.html

20. Further Research • Roll off angle • There has been a lot of confirmed research in the area of Contact angle. • But, little to no information is given on Roll off Angle. • Research in this area would consist of experimentally finding correlations between Roll off Angle and specific qualities of materials. • End goal of statistical model for roll off angle.

21. References • Contact angle. (n.d.). Retrieved from http://membranes.edu.au/wiki/index.php/Contact_Angle • Deng, X., Mammen, L., Butt, H. & Vollmer, D. (2011, 12 01). Candle soot as a template for a transparent robust superamphiphobic coating. Science, 335, 6064. Retrieved from http://www.sciencemag.org/content/335/6064/67.abstract?sid=b8cea070-e429-4c98-897c-8c6b8adb8dc3 • Diversified Enterprises. (2009). Critical surface tension and contact angle with water for various polymers. Retrieved from http://www.accudynetest.com/polytable_03.html? • All uncited figures are taken from cited paper