BY: G R O U P 1 8

CANDLE SOOT AS A TEMPLATE FOR A TRANSPARENT ROBUST

SUPERAMPHIPHOBIC COATING

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

INTRODUCTION

Examples of Hydrophobic materials

• Polyethylene• Polypropylene• Nylon 10,10

Examples of Oleophobic materials

• 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

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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

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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

• 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.

FURTHER RESEARCH

http://www.chemspider.com/Chemical-Structure.10328917.html

• 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.

FURTHER RESEARCH

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