Creating the New Teflon: The Use of Phosphonic Acids to
Download
Report
Transcript Creating the New Teflon: The Use of Phosphonic Acids to
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®?
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
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
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