IMPROVING THE HYDROPHOBICITY OF
KITCHENWARE THROUGH THE COVALENT
BONDING OF PHOSPHONIC ACIDS
Emily Chen, Marcus Elias, Jonathan Lin, Nathaniel Okun
Olabade Omole, Matthew Piccolella, Suraj Shukla
Dominique Voso, Jonathan Wu, Peter Xiong, Tania Yu
Advisor: Dr. Michael Avaltroni
Assistant: Liz Day
What is Teflon®?
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Polytetrafluoroethylene
Highly hydrophobic
Gold standard for non-stick cookware
Durable, easy-to-clean
Dangerous
Remains in the body for 20 years
Lab studies on rats reveal liver damage, cancer, etc.
Carcinogenic at high temperatures, flu-like symptoms
Other Current Methods
 Siloxanes
 Used in Rain-X
 Long molecules with silicon group at head
 The industry standard to coat surfaces
 Unreliable, can be easily removed by water
 Physical attraction to a surface doesn’t work well for oxide
surfaces
 Material needs to be bonded covalently
What is a SAM?
 Self-Assembled Monolayers – thin film (10 nm) that is
physically (electrostatic) or chemically (covalent)
bound to a surface
 Bind to oxide surfaces
 µ-oxo groups: bridged oxygens on a surface, unreactive
 Hydroxyl groups: -OH groups, more reactive
 Can be achieved with phosphonic acids
What is a Phosphonic Acid?
 Phosphonate group with n-carbon chain attached at
the head
 Covalently bonds at two locations on an oxide surface,
creating a self-assembled monolayer
 “Controlled Corrosion”
 tightly bound
 permanently attached
 completely covers surface
Possible Applications of SAMPs
 Water repellents for electronics
 Stents for the heart
 Orthopedic Implants
 Non-Stick Cookware
Our Hypotheses
 Longer carbon chain lengths will cause more
hydrophobic surfaces
 Washing the samples will increase hydrophobicity
 The oven heating method will be the most effective
 Aluminum will improve the most
Materials and Methods
 Household materials tested
 Tile, glass, aluminum
 Coatings
 Phosphonic acids with C-6, C-8, C-10, C-12, C-14, C-16,
and C-18 tails
 Different heating methods
 Oven, heat gun, iron
Materials and Methods
 Preparing Materials
 Cleaned each material using a warm bath of ethanol
 Sanded the aluminum
 Preparing Solutions
 0.0001 mol of each acid dissolved in 100. mL of 50%
toluene and 50% ethanol by volume as solvent
 Mixed polarity provides best bonding
 Applying
 Spray bottle to apply, one spray to each surface
 Rolled each surface with a Mayer Rod to ensure even
coating
Materials and Methods
 Bonding
 Phosphonic acid was bonded to the surface either
by oven (24 hours at 120°C), iron (5 minutes on
highest setting), or heat gun (3 minutes on highest
setting)
 Wear Testing
 Distilled water for 5 minutes
 Rubbed with 50:50 soap-water solution
Goniometer
 Used to measure the hydrophobicity of the surfaces
 5 microliter droplet added to each surface
 Uses infrared light and a high definition camera to
take an image of a water droplet
 Used computer applications to measure the base
angles
Results
 Oven Trials
 C-6,8,10,12,14,16,18 were applied to the three materials
with the oven heating method
 Two wear tests
 Water rinse
 Soap-water rub
 Found that Increases in alkyl groups correspond to
increases in hydrophobicity (verified our hypothesis)
 Tile Samples with Oven Heating
80
70
CONTACT ANGLE (DEGREES)
60
Untreated
50
40
Water
30
20
Soap
10
0
Tile Control
Tile C6
Tile C8
Tile C10
Tile C12
Tile C14
Tile C16
Tile C18
Oven Trial Results
 Improvement in hydrophobicity
 Changes in hydrophobicity from the control to the C-18
samples
 Glass increased 60.00o (201.9%)
 Tile increased 17.71o (33.76%)
 Aluminum increased 30.77o (49.94%)
 Wear Tests
 Changes in the hydrophobicity of the C-18 samples
before and after soap washes
 Glass increased 4.80o (6.60%)
 Tile decreased 4.72o (6.73%)
 Aluminum decreased 50.90o (55.10%)
Oven Trial Results
 Found that aluminum had best overall results (though
not the best improvement)
 Comparing C-18 samples
Aluminum: 92.37o (hydrophobic)
Glass: 72.78o
Tile: 70.17o
Heating Methods Results
 Used C-18 on all three surfaces
120
CONTACT ANGLE (DEGREES)
100
Tile C18
80
60
Glass C18
40
20
Aluminum
C18
0
Oven
Heat Gun
Iron
Heating Method Results
 The oven proved to be the best and most consistent
 Even, constant spread of heat
 Relatively low temperatures
 The iron is still a viable option
 Economically feasible
 Time constraints
 Only slightly lower results
 The heat gun was consistently ineffective
 High temperatures decomposed the phosphonic acids
Corollary Trials and Results
 The group then decided to use the iron
with phosphonic acids C-14,16, & 18
 Hypothesized that the second coating
would fill in the “gaps” in coating and
create even coverage
Corollary Trial Results
 The effects of a second coating
 Glass- 7.35° increase (11.57%)
 Tile- 11.44° increase (15.79%)
 Aluminum- 2.22° increase (2.90%)
 The group then decided to examine how the wear
tests would affect the double-coated samples
Wear Tests on Double-Coated, C-18 Samples
115
CONTACT ANGLE (DEGREES)
95
Control
75
Untreated
55
35
Soap
15
-5
Tile
Glass
Aluminum
Opportunities for Future
Research
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Multiple coatings
Different solvents
Various heating methods
Different carbon-chain lengths
Other testing surfaces
Increasing accuracy and precision
Sources of Error
 Possible Systematic Errors
 Uneven heating coverage from the heat gun
 Cross-contamination (Mayer Rod, heating iron etc.)
 Human error
 Slightly different procedures
 Not the exact same amount of solution was applied to each sample
 Concentration of phosphonic acid solutions
 Possible Random Errors
 Slight equipment malfunctions
 The scale used only measured weight to the third significant figure
In Conclusion
 C-18 was the most effective at increasing
hydrophobicity
 Glass was the most receptive surface for covalent
bonding
 Constant, relatively low heat, was the most effective
heating method
Acknowledgements
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Dr. Avaltroni
Dr. Miyamoto
Liz Day
The NJGSS Staff
 Janet Quinn
 Anna Mae Dinnio-Bloch
 John and Laura Overdeck
 The Crimmins Family Charitable Foundation
 NJGSS Alumni and Parents 1984 – 2012