IMPROVING THE HYDROPHOBICITY OF KITCHENWARE THROUGH THE COVALENT BONDING OF PHOSPHONIC ACIDS Emily Chen, Marcus Elias, Jonathan Lin, Nathaniel Okun Olabade.

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 AvaltroniAssistant: Liz Day

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

What is Teflon®?

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

Other Current Methods

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 SAM?

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

What is a Phosphonic Acid?

Water repellents for electronics Stents for the heart Orthopedic Implants Non-Stick Cookware

Possible Applications of SAMPs

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

Our Hypotheses

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

Materials and Methods

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

Goniometer

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)

Results

Tile Samples with Oven Heating

Tile Control Tile C6 Tile C8 Tile C10 Tile C12 Tile C14 Tile C16 Tile C180

10

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50

60

70

80

Untreated Water

Soap

CO

NTA

CT A

NG

LE (

DEG

REES

)

Improvement in hydrophobicity Changes in hydrophobicity from the control to

the C-18 samplesGlass 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 washesGlass 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 samplesAluminum: 92.37o (hydrophobic)Glass: 72.78o

Tile: 70.17o

Oven Trial Results

Used C-18 on all three surfaces

Heating Methods Results

_x0004_Oven Heat Gun _x0005_ Iron0

10

20

30

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50

60

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80

90

100

Tile C18

Glass C18

Aluminum C18CO

NTA

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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

The effects of a second coatingGlass- 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

Corollary Trial Results

Wear Tests on Double-Coated, C-18 Samples

_x0004_Tile _x0006_ Glass Aluminum-5

15

35

55

75

95

115

Control Untreated

Soap

CO

NTA

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DEG

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Multiple coatings Different solvents Various heating methods Different carbon-chain lengths Other testing surfaces Increasing accuracy and precision

Opportunities for Future Research

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

Sources of Error

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

In Conclusion

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

Acknowledgements