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ramé-hart instrument co. February 2014 Newsletter
|101 Superhydrophobic Surfaces|
We are in the midst of a superhydrophobic revolution. Twenty years from now we will look back at this era as the beginning of non-wetting, the time when we were just beginning to figure out how to make materials and surfaces that are self-cleaning and liquid-resistant. If you've been reading our newsletters, or if you browse through our back issues (http://www.ramehart.com/newsletters.htm), you will notice they are sprinkled with random stories of how people are making life better for themselves and others by making surfaces superhydrophobic - everything from ketchup bottles to my shower curtain, motorcycle windscreen, and sneakers. Our aim this month is to present a nearly comprehensive list of surfaces and applications that can benefit from becoming superhydrophobic. We are not aware of a list like this anywhere else. If you are, please let us know as we would like our list definitive. We acknowledge that there are many additional applications that are not in the list. If you are aware of any, please let us know so we can add them to our next such list. Here goes, in no particular order:
1. Self-cleaning clothes. We featured a story on superhydrophobic Army fatigues in our January newsletter: http://www.ramehart.com/newsletters/2013-12_news.htm. See also: http://youtu.be/WLIWoUv3j50
2. Shoes, boots, and sneakers. In August I told you about how I made my Puma Clyde sneakers superhydrophobic for less than $20: http://www.ramehart.com/newsletters/2013-08_news.htm. Work boots and all types of shoes can benefit from being made to repel water and mud. See also http://youtu.be/a_THjydSNZU.
3. Ketchup (and condiment) bottles (on the inside). Researchers from MIT are on top of this one: http://www.ramehart.com/newsletters/2013-01_news.htm.
4. Swimsuits made like shark skin. See item 5 here: http://www.ramehart.com/newsletters/2013-04_nes.htm. Perhaps we will revisit this topic in the near future.
5. Toilet plungers: http://youtu.be/VgrA5vNryQk
See http://youtu.be/IfUaKXasdD4 for items 7-13.
7. Blocks and bricks.
9. Bolts and hardware.
11. Tarps and drop clothes.
13. Concrete chutes.
See http://youtu.be/WLIWoUv3j50 for items 14-17.
14. Shipping cartons.
15. Smart phone and tablet screens.
17. Building materials (e.g., wood).
See http://youtu.be/hbXwcK_JaHc for items 18-20.
20. Hats. See also http://youtu.be/0xX_wBOEGvY.
21. Baby potties. See http://youtu.be/yn0Qd9eY-IM.
22. Umbrellas. See http://youtu.be/4hefDzQfqcY.
23. Boat paddles and oars. See http://youtu.be/48za8YTyF7k.
24. Handbags. See http://youtu.be/a_THjydSNZU.
26. Car bodies. See http://youtu.be/9qTxsKymXYw.
27. Tool chests. http://youtu.be/6mHm1xKs31g
28. Knives. See http://youtu.be/yTCaSzZ7MO0.
29. Solar panels. See http://www.ramehart.com/newsletters/2009-08_news.htm.
30. Motorcycle screens. See http://www.ramehart.com/newsletters/2011-02_news.htm.
31. Toll both sensors.
32. Traffic light cameras.
33. Frying pans.
34. Shower walls and curtains. See http://www.ramehart.com/newsletters/2008-10_news.htm.
35. Eyeglasses and goggles. See http://tinyurl.com/oe3r6ek.
36. Electronics. See http://tinyurl.com/n4pc327.
37. Shingles. http://tinyurl.com/kwzscvv.
38. Power lines. See http://www.ramehart.com/newsletters/2007-11_news.htm and http://tinyurl.com/m6skpcr.
39. Building exteriors. See http://tinyurl.com/2ut636o.
40. Rice makers (especially the inside of the pan).
41. Fake plastic plants. What the heck, if there are plants like the lotus flower which are naturally superhydrophobic, why not make fake ones that also repel water and have self-cleaning leaves? They even might look more real and less dusty than the old ones.
42. Deck and outdoor furniture.
43. Snow skis.
44. Commercial office building windows. Lower maintenance cost with self-cleaning properties.
45. Submarine propellers.
46. Wind turbines. See http://tinyurl.com/k25j3de.
48. Lenses for airport runway lights.
49. Sink fixtures and faucets.
50. Side view mirrors.
51. Traffic camera lens.
52. Deck umbrellas.
53. Motorcycle helmets.
54. Snow shovels.
55. Bicycle components.
57. Boat and ship hulls for less drag and fewer barnacles.
59. Snow boards.
62. Flashlight lenses.
63. BBQ grills.
64. Car wheels - especially cast aluminum.
65. Tents and tent materials.
67. Outdoor electrical outlets and switch covers.
68. Bridge pilings.
69. Power transformer casings.
70. Traffic signals and sensors.
71. Water fountains.
72. Boat propellers.
73. Cables used on suspension bridges.
74. Wooden and synthetic decks.
75. Stents and other medical devices. See http://www.google.com/patents/US8043359.
76. Tree limbs.
78. Sleeping bags.
80. Balls used for soccer, football, etc.
81. Military gear.
82. Seats on amusement park rides.
83. Motorcycle seats.
84. Horse saddles.
85. Helicopter rotor blades (to obtain anti-icing property). See http://tinyurl.com/ktg98su.
86. Aircraft body parts (for the same anti-icing benefits).
88. Ponchos (for hiking).
89. Outdoor stadium seats.
91. Gutters (on houses and commercial buildings).
92. Playground equipment.
93. Field notebooks.
94. Car top soft cargo bag.
95. Automotive headlight lens.
96. Satellite dishes.
97. Outdoor mail drop boxes.
98. Wristwatches and bands.
99. Park benches.
100. Roofing shingles and materials.
101. Statues and fountains.
|Nanotechnology and Superhydrophobicity|
|The driving force behind the superhydrophobic revolution is nanotechnology. Researchers are becoming increasingly adept at developing and improving methods for producing nanotopography and micro-nanostructured surfaces. The creation of surfaces and coatings that promote the Cassie-Baxter regime is followed by constant tweaking and improvement in order to minimize wetting, decrease contact angle hysteresis and increase contact angle which, to be superhydrophobic, is considered greater than 150°. Researchers turn to nature to find some of the finest examples of superhydrophobicity (e.g., the Lotus leaf). Manmade methods for mimicking these types of surfaces have led to accelerated development using plasma treatments, sol-gel methods, nanopin films, particle deposition, SAM coatings, and vapor deposition. These studies have also led to the development of surfaces with tunable wettability. It's an exciting time to be non-wetting and things are only getting more superhydrophobic by the day. Stay tuned for more developments in this corner of the world of surface science.|