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

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

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

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

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

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

www.ramehart.com

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)

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

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

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

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

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

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

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

Assessment of the work Analysis The paper presents a practical approach to making a superamphiphobic coating 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

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

Further research How to make Fluorosilane remain stabile at higher temps As we have shown in our Work Performed, Fluorosilane began to break down at 400˚C- meaning coating lost its superamphibhobic properties For our superamphiphobic material to more use,we need to increase to temperature range in which Fluorosilane remains 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

Further research Sand Abrasion The Sand Abrasion Test showed that the superamphiphobic material 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

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.

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