Concepts like the “frictionless surface” enabled Newton to lay the groundwork for modern physics. He may never have imagined that his ideal could actually be achieved, but now, thanks to a group of tribologists (scientists who study interacting surfaces in relative motion), the prospect of eliminating friction between two interacting surfaces has come to fruition. And there are a number interesting ways in which frictionless surfaces promise to improve our daily lives. Here are 10 crazy uses for frictionless surfaces:
1. Sharkskin Swimsuits
Want to swim like a shark? Then you’ll need skin like a shark. While you can’t change your body’s skin, you can don a high-tech bodysuit like the LZR Racer from Speedo. This swimsuit uses polyurethane panels to trap air and compress the body to increase buoyancy and reduce drag. The suit’s fabric is coated with hydrophobic nanoparticles that actually repel water and decrease friction along the swimmer’s body.
2. Non-Stick Gum
How many times have you stepped on inappropriately discarded gum on city streets and sidewalks? Not only is it annoying, but it also costs money for cities to remove it. But that may soon change, thanks to scientists at UK-based polymer company, Revolymer. They’ve created a revolutionary gum called Rev7 that can be easily removed from a range of surfaces, including paved sidewalks, carpets, textiles and clothing.
To give Rev7 its nonstick properties, a chemical is added to the gum base that is both hydrophilic (water-loving) and hydrophobic (water-hating or oil-loving). The polymer’s affinity for oil makes the gum soft and pliable, but its attraction to water means the gum always has a film of water around it, even when it’s not being chewed. It’s this film of water that allows Rev7 to be peeled away from any surface.
3. Anti-Barnacle Boat Hulls
Barnacles are a major concern for seafaring vessels like navies, marinas and commercial fishing boats. They form when small saltwater crustaceans adhere to a hull or propeller and decrease the vessel’s efficiency—a process known as “biofouling.” It’s a serious problem that costs the U.S. Navy $56 million per year for just one class of vessel: Arleigh Burke-class guided missile destroyers.
But now, scientists have created a micro-textured material (which contains tiny peaks and valleys ranging in size from 1 to 100 micrometers) that reduces barnacle settlement by 92 percent. The research may lead to the first nonstick, barnacle-blasting vessel of the future.
4. Clog-Free Pipes
How annoying is it when a pipe clogs? This pesky plumbing predicament begins when debris clings to the inside of a pipe and then acts as a nucleus upon which other material collects. For example, if you pour grease into the kitchen sink, it sticks to the sides of the pipe, and then food particles stick to the grease. As the obstruction grows over time, water backs up behind the blockage. For now, there are Sani Sticks, Drano, and Roto-Rooter. But in the future, we may well see the dawn of clogless pipes, thanks to frictionless coatings being developed by more than one company.
For example, chemical manufacturers commonly use tubing lined with polytetrafluoroethylene, or PTFE, which you know by its common brand name—Teflon (the same material that coats nonstick frying pans). When used in pipes and tubing, PTFE prevents fouling and clogs.
5. Self-Cleaning Cars
Everyone loves the look of a fresh-out-of-the-showroom, new car, truck, van, or SUV. But maintaining that lustrous look is a time-consuming and somewhat expensive proposition. Until now, all anyone could do was wish for a self-cleaning car. Thanks to some researchers at the Eindhoven University of Technology in the Netherlands, we may be closer to that than you think.
Dutch scientists have taken an existing water-resistant product, which was embedded with nanocapsules in its surface (already in use on some vehicles), and have improved it. To extend the self-cleaning/healing properties of the coating, the scientists have redesigned its nanostructure so that the capsules reside on stalks. When one capsule/stalk gets disturbed, another underlying stalk rises up and positions itself at the surface to restore the factory finish.
So, somewhere down the road, you just may be able to say goodbye to road tar and bird droppings that mar your vehicle’s finish.
6. Graffiti-Repelling Walls
While some graffiti is artistic, the vast majority of it is viewed by many people to be an eyesore. But, it’s everywhere. No longer a “city” thing, graffiti can be found in numerous suburban areas as well, and even in small towns across America. Eradicating it can be a time-consuming and expensive process that costs millions of dollars and rarely restores buildings, bridges, tunnels, and train cars to their former glory without totally repainting the surface. And, unfortunately, some of the cleaning and removal methods that are used produce a bigger eyesore than the graffiti itself.
But now, graffiti has a bigger foe than the police and cleaning crews combined: the graffiti-repelling wall, which features a non-stick material that either resists paint adhesion or makes removal far easier because the paint doesn’t interact with the protected surface. Scientists have fashioned one such material to mimic the leaves of the lotus flower. A wall or sign coated in such a material promises to foil graffiti artists and save cities millions of dollars every year.
7. Bacterial-Resistant Surfaces
You might think that fastidious cleaning is the answer to bacterial buildup on surfaces we touch every day. But biofilms (microbes—bacteria, fungi, and certain viruses—that attach to surfaces) stubbornly resist scrubbing. Bacterial-based biofilms also tend to shrug off the effects of antibiotics, and antibiotics are completely ineffective against viruses. This poses a health hazard for everyone, particularly those who work in healthcare settings.
A biofilm begins its life when a few devil-may-care microorganisms adhere to a countertop, surgical instrument or soap dispenser, either by way of gluey adhesion molecules or structures known as pili. Once attached, this small group of cells secretes an extracellular polymeric substance, or EPS, which acts like cement to hold the cells—and their progeny—permanently in place. If you can interrupt this attachment process, you can stop the biofilm from forming. No biofilm—no health hazard.
The good news is that scientists in the UK have discovered a solution. By coating laboratory surfaces and medical devices with an acrylate polymer (similar to those used in the plastics industry), researchers have been able to prevent bacteria from establishing a foothold on surfaces. In fact, the result was a 97 percent reduction in the adherence of the Staphylococcus aureus bacterium.
8. Non-Stick Condiment Bottles
Scientist Kripa Varanasi’s wife, Manasa, was trying to make a snack for their young son. She was struggling to spoon out some honey from a jar, frustrated by how hard it was to get the last bits of sticky sweetness to dislodge from the bottom of the container.
Finally, she turned to her husband. “You work on slippery things,” she said. “Why can’t you make a slippery bottle?”
Varanasi, an associate professor of mechanical engineering, had a hunch that focusing on interfaces would prove useful. As he worked on real-world problems in a variety of industries, he indeed began to notice a common thread: inefficiencies often arose from the way materials behave at interfaces, the places where a solid surface makes contact with liquids, gases, or other solids.
Varanasi found that small changes at those interfaces could produce big results. He and his student, David Smith, realized that by creating a surface with a sufficiently fine microscale or nanoscale texture, they could harness capillary forces—the same thing that lets water rise up inside a tree’s tiny internal passageways—to hold a lubricant securely in place. After a lot of experiments, they found combinations that achieved just that: they could pattern the surface by scoring or etching (or, later, by spraying a special coating), and then a layer of oil or other lubricant applied to that surface would be anchored solidly in place in its tiny crevices. It worked, and the coatings proved to be amazingly durable. And Varanasi’s company, LiquiGlide, was born.
The ketchup bottle—a vessel that famously retains its contents despite pounding, shaking, and coaxing—was what really caught people’s attention. And with that consumer-oriented approach, the company branched out. Now, LiquiGlide tests and tweaks customized versions of its coatings to work with a wide variety of thick, viscous liquids. One industry that could benefit from LiquiGlide’s coatings is paint manufacturing. Paint manufacturers lose up to 30 percent of their production runs when paint sticks to mixing tanks and has to be washed away with a large volume of water that becomes contaminated in the process.
9. Non-Stick Submarines
For more than 200 years, scientists have looked for ways to eliminate one of the submarine’s most vexing problems: friction drag, a force that opposes forward motion as water sticks to the surface of the outer hull. According to some estimates, this “skin friction” accounts for roughly 65 percent of the drag on submarines.
One of the first ways in which scientists battled this was with a polymer injection system. But now, they’ve come up with a better solution: a revolutionary new nanotechnology. Under a microscope, tiny needles spaced apart by just a couple millionths of a meter are visible. The needles rest, like a layer of grass, on a surface of Teflon. When water hits the material, it encounters air trapped in the spaces between the needles. As a result, it makes the material extremely slippery—99 percent less sticky than a normal Teflon surface without the nano-sized needles. Submarines coated in the nanotechnology would have far less friction drag and would require less fuel to propel them.
10. De-Icing System for Planes
When airplane wings become coated with even a thin layer of snow or ice, their ability to keep a plane in the air is greatly diminished. In fact, by some estimates, ice buildup can reduce lift by as much as 25 percent, which is why ground and flight crews worry so much about de-icing during wintertime air travel.
Several types of nanotechnology may soon enable planes to be built with a surface so smooth that ice would not be able to form on the plane’s wings. Scientists from GE Global Research have developed a nanotextured, superhydrophobic (or water-repellent) coating that dramatically reduces ice adhesion on wing surfaces.
And a team at North Carolina State University is experimenting with a nonstick polymer that works together with an elastic substrate. The polymer gets applied to the substrate when the elastic material is stretched slightly. When the tension is relieved, the substrate pulls the polymer molecules together into a superdense configuration. Airplane wings coated with the friction-free polymers resist being coated by anything—even ice.