In an effort to curb global warming, Purdue University engineers have created the whitest paint yet. Coating buildings with this paint may one day cool them off enough to reduce the need for air conditioning, the researchers say.
In October , the team created an ultra-white paint that pushed limits on how white paint can be. Now they’ve outdone that. The newer paint not only is whiter but also can keep surfaces cooler than the formulation that the researchers had previously demonstrated.
“If you were to use this paint to cover a roof area of about 1,000 square feet, we estimate that you could get a cooling power of 10 kilowatts. That’s more powerful than the central air conditioners used by most houses,” said Xiulin Ruan, a Purdue professor of mechanical engineering.
This is nicely done. Researcher Xiulin Ruan is standing close to a structure that could be said to resemble the sun while in shirtsleeves and sunglasses and holding up a sample of his whitest paint in April (not usually a warm month in Indiana).
The researchers believe that this white may be the closest equivalent of the blackest black, “Vantablack,” [emphasis mine; see comments later in this post] which absorbs up to 99.9% of visible light. The new whitest paint formulation reflects up to 98.1% of sunlight – compared with the 95.5% of sunlight reflected by the researchers’ previous ultra-white paint – and sends infrared heat away from a surface at the same time.
Typical commercial white paint gets warmer rather than cooler. Paints on the market that are designed to reject heat reflect only 80%-90% of sunlight and can’t make surfaces cooler than their surroundings.
The team’s research paper showing how the paint works publishes Thursday (April 15 ) as the cover of the journal ACS Applied Materials & Interfaces.
What makes the whitest paint so white
Two features give the paint its extreme whiteness. One is the paint’s very high concentration of a chemical compound called barium sulfate [emphasis mine] which is also used to make photo paper and cosmetics white.
“We looked at various commercial products, basically anything that’s white,” said Xiangyu Li, a postdoctoral researcher at the Massachusetts Institute of Technology who worked on this project as a Purdue Ph.D. student in Ruan’s lab. “We found that using barium sulfate, you can theoretically make things really, really reflective, which means that they’re really, really white.”
The second feature is that the barium sulfate particles are all different sizes in the paint. How much each particle scatters light depends on its size, so a wider range of particle sizes allows the paint to scatter more of the light spectrum from the sun.
“A high concentration of particles that are also different sizes gives the paint the broadest spectral scattering, which contributes to the highest reflectance,” said Joseph Peoples, a Purdue Ph.D. student in mechanical engineering.
There is a little bit of room to make the paint whiter, but not much without compromising the paint.”Although a higher particle concentration is better for making something white, you can’t increase the concentration too much. The higher the concentration, the easier it is for the paint to break or peel off,” Li said.
How the whitest paint is also the coolest
The paint’s whiteness also means that the paint is the coolest on record. Using high-accuracy temperature reading equipment called thermocouples, the researchers demonstrated outdoors that the paint can keep surfaces 19 degrees Fahrenheit cooler than their ambient surroundings at night. It can also cool surfaces 8 degrees Fahrenheit below their surroundings under strong sunlight during noon hours.
The paint’s solar reflectance is so effective, it even worked in the middle of winter. During an outdoor test with an ambient temperature of 43 degrees Fahrenheit, the paint still managed to lower the sample temperature by 18 degrees Fahrenheit.
This white paint is the result of six years of research building on attempts going back to the 1970s to develop radiative cooling paint as a feasible alternative to traditional air conditioners.
Ruan’s lab had considered over 100 different materials, narrowed them down to 10 and tested about 50 different formulations for each material. Their previous whitest paint was a formulation made of calcium carbonate, an earth-abundant compound commonly found in rocks and seashells.
The researchers showed in their study that like commercial paint, their barium sulfate-based paint can potentially handle outdoor conditions. The technique that the researchers used to create the paint also is compatible with the commercial paint fabrication process.
Patent applications for this paint formulation have been filed through the Purdue Research Foundation Office of Technology Commercialization. This research was supported by the Cooling Technologies Research Center at Purdue University and the Air Force Office of Scientific Research [emphasis mine] through the Defense University Research Instrumentation Program (Grant No.427 FA9550-17-1-0368). The research was performed at Purdue’s FLEX Lab and Ray W. Herrick Laboratories and the Birck Nanotechnology Center of Purdue’s Discovery Park.
Vantablack’s 99.9% light absorption no longer qualifies it for the ‘blackest black’. A newer standard for the ‘blackest black’ was set by the US National Institute of Standards and Technology at 99.99% light absorption with its N.I.S.T. ultra-black in 2019, although that too seems to have been bested.
I have three postings covering the Vantablack and blackest black story,
The third posting (December 2019) provides a brief summary of the story along with what was the latest from the US National Institute of Standards and Technology. There’s also a little bit about the ‘The Redemption of Vanity’ an art piece demonstrating the blackest black material from the Massachusetts Institute of Technology, which they state has 99.995% (at least) absorption of light.
From a science perspective, the blackest black would be useful for space exploration.
I am surprised there doesn’t seem to have been an artistic rush to work with the whitest white. That impression may be due to the fact that the feuds get more attention than quiet work.
Dark side to the whitest white?
Andrew Parnell, research fellow in physics and astronomy at the University of Sheffield (UK), mentions a downside to obtaining the material needed to produce this cooling white paint in a June 10, 2021 essay on The Conversation (h/t Fast Company), Note: Links have been removed,
… this whiter-than-white paint has a darker side. The energy required to dig up raw barite ore to produce and process the barium sulphite that makes up nearly 60% of the paint means it has a huge carbon footprint. And using the paint widely would mean a dramatic increase in the mining of barium.
Parnell ends his essay with this (Note: Links have been removed),
Barium sulphite-based paint is just one way to improve the reflectivity of buildings. I’ve spent the last few years researching the colour white in the natural world, from white surfaces to white animals. Animal hairs, feathers and butterfly wings provide different examples of how nature regulates temperature within a structure. Mimicking these natural techniques could help to keep our cities cooler with less cost to the environment.
The wings of one intensely white beetle species called Lepidiota stigma appear a strikingly bright white thanks to nanostructures in their scales, which are very good at scattering incoming light. This natural light-scattering property can be used to design even better paints: for example, by using recycled plastic to create white paint containing similar nanostructures with a far lower carbon footprint. When it comes to taking inspiration from nature, the sky’s the limit.
I love the video (wish the narrator had a more conversational style rather than the ‘read aloud’ style so many of us adopted in school),
Joel Goldberg’s April 28, 2021 news article (short read) in Science magazine online describes the research (Note: A link has been removed),
Behold the salt monsters. These twisted mineral crystals—formed from the buildup of slightly salty water in power plant pipes—come in many shapes and sizes. But the tiny monsters are a big problem: Each year, they cost the world’s power plants at least $100 billion because workers have to purge the pipes and scrub the crystals from filters.
Now, a solution may be at hand. Engineers can reduce the damage by coating the insides of the pipes with textured, water-repellant [hydrophobic] surfaces …
This paper is open access. As research papers go, this is quite readable, from the Introduction (Note: Links have been removed),
Many of the uses for water are intimately familiar to us. Drinking water, wash water, water for agriculture, and even water used for recreation have an omnipresent and essential impact on our lives. However, water’s impact and importance extend far beyond these everyday uses. In many developed countries, thermoelectric power production is one of the largest sources of water consumption (1), where it is used to cool reactors and transport heat. In 2015, 41% of all surface water withdrawals in the United States went toward cooling in thermoelectric power plants (2). Thermoelectric power accounts for 90% of all electricity generated within the United States and encompasses many forms of power production, including nuclear, coal, natural gas, and oil.
A Dec. 7, 2020 news item on Nanowerk announced a new technology for rapid COVID-19 testing (Note: A link has been removed),
As the COVID-19 pandemic continues to spread across the world, testing remains a key strategy for tracking and containing the virus. Bioengineering graduate student, Maha Alafeef, has co-developed a rapid, ultrasensitive test using a paper-based electrochemical sensor that can detect the presence of the virus in less than five minutes.
The team led by professor Dipanjan Pan reported their findings in ACS Nano (“Rapid, Ultrasensitive, and Quantitative Detection of SARS-CoV-2 Using Antisense Oligonucleotides Directed Electrochemical Biosensor Chip”).
“Currently, we are experiencing a once-in-a-century life-changing event,” said Alafeef. “We are responding to this global need from a holistic approach by developing multidisciplinary tools for early detection and diagnosis and treatment for SARS-CoV-2.”
I wonder why they didn’t think to provide a caption for the graphene substrate (the square surface) underlying the gold electrode (the round thing) or provide a caption for the electrode. Maybe they assumed anyone knowledgeable about graphene would be able to identify it?
There are two broad categories of COVID-19 tests on the market. The first category uses reverse transcriptase real-time polymerase chain reaction (RT-PCR) and nucleic acid hybridization strategies to identify viral RNA. Current FDA [US Food and Drug Administration]-approved diagnostic tests use this technique. Some drawbacks include the amount of time it takes to complete the test, the need for specialized personnel and the availability of equipment and reagents.
The second category of tests focuses on the detection of antibodies. However, there could be a delay of a few days to a few weeks after a person has been exposed to the virus for them to produce detectable antibodies.
In recent years, researchers have had some success with creating point-of-care biosensors using 2D nanomaterials such as graphene to detect diseases. The main advantages of graphene-based biosensors are their sensitivity, low cost of production and rapid detection turnaround. “The discovery of graphene opened up a new era of sensor development due to its properties. Graphene exhibits unique mechanical and electrochemical properties that make it ideal for the development of sensitive electrochemical sensors,” said Alafeef. The team created a graphene-based electrochemical biosensor with an electrical read-out setup to selectively detect the presence of SARS-CoV-2 genetic material.
There are two components [emphasis mine] to this biosensor: a platform to measure an electrical read-out and probes to detect the presence of viral RNA. To create the platform, researchers first coated filter paper with a layer of graphene nanoplatelets to create a conductive film [emphasis mine]. Then, they placed a gold electrode with a predefined design on top of the graphene [emphasis mine] as a contact pad for electrical readout. Both gold and graphene have high sensitivity and conductivity which makes this platform ultrasensitive to detect changes in electrical signals.
Current RNA-based COVID-19 tests screen for the presence of the N-gene (nucleocapsid phosphoprotein) on the SARS-CoV-2 virus. In this research, the team designed antisense oligonucleotide (ASOs) probes to target two regions of the N-gene. Targeting two regions ensures the reliability of the senor in case one region undergoes gene mutation. Furthermore, gold nanoparticles (AuNP) are capped with these single-stranded nucleic acids (ssDNA), which represents an ultra-sensitive sensing probe for the SARS-CoV-2 RNA.
The researchers previously showed the sensitivity of the developed sensing probes in their earlier work published in ACS Nano. The hybridization of the viral RNA with these probes causes a change in the sensor electrical response. The AuNP caps accelerate the electron transfer and when broadcasted over the sensing platform, results in an increase in the output signal and indicates the presence of the virus.
The team tested the performance of this sensor by using COVID-19 positive and negative samples. The sensor showed a significant increase in the voltage of positive samples compared to the negative ones and confirmed the presence of viral genetic material in less than five minutes. Furthermore, the sensor was able to differentiate viral RNA loads in these samples. Viral load is an important quantitative indicator of the progress of infection and a challenge to measure using existing diagnostic methods.
This platform has far-reaching applications due to its portability and low cost. The sensor, when integrated with microcontrollers and LED screens or with a smartphone via Bluetooth or wifi, could be used at the point-of-care in a doctor’s office or even at home. Beyond COVID-19, the research team also foresees the system to be adaptable for the detection of many different diseases.
“The unlimited potential of bioengineering has always sparked my utmost interest with its innovative translational applications,” Alafeef said. “I am happy to see my research project has an impact on solving a real-world problem. Finally, I would like to thank my Ph.D. advisor professor Dipanjan Pan for his endless support, research scientist Dr. Parikshit Moitra, and research assistant Ketan Dighe for their help and contribution toward the success of this study.”
I’m not sure where I found this notice but it is most definitely from the American Chemical Society: “This paper is freely accessible, at this time, for unrestricted RESEARCH re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.”
A simple method for making clear coatings that can block heat and conduct electricity could radically cut the cost of energy-saving smart windows and heat-repelling glass [electrochromic windows?].
The spray-on coatings developed by researchers at RMIT are ultra-thin, cost-effective and rival the performance of current industry standards for transparent electrodes.
Combining the best properties of glass and metals in a single component, a transparent electrode is a highly conductive clear coating that allows visible light through.
The coatings – key components of technologies including smart windows, touchscreen displays, LED lighting and solar panels – are currently made through time-consuming processes that rely on expensive raw materials.
The new spray-on method is fast, scalable and based on cheaper materials that are readily available.
The method could simplify the fabrication of smart windows, which can be both energy-saving and dimmable, as well as low-emissivity glass, where a conventional glass panel is coated with a special layer to minimise ultraviolet and infrared light.
Lead investigator Dr Enrico Della Gaspera said the pioneering approach could be used to substantially bring down the cost of energy-saving windows and potentially make them a standard part of new builds and retrofits.
“Smart windows and low-E glass can help regulate temperatures inside a building, delivering major environmental benefits and financial savings, but they remain expensive and challenging to manufacture,” said Della Gaspera, a senior lecturer and Australian Research Council DECRA Fellow at RMIT.
“We’re keen to collaborate with industry to further develop this innovative type of coating.
“The ultimate aim is to make smart windows much more widely accessible, cutting energy costs and reducing the carbon footprint of new and retrofitted buildings.”
The new method can also be precisely optimised to produce coatings tailored to the transparency and conductivity requirements of the many different applications of transparent electrodes.
Global demand for smart glazing
The global market size for smart glass and smart windows is expected to reach $6.9 billion by 2022, while the global low-E glass market is set to reach an estimated $39.4 billion by 2024.
New York’s Empire State Building reported energy savings of $US2.4 million and cut carbon emissions by 4,000 metric tonnes after installing smart glass windows.
Eureka Tower in Melbourne features a dramatic use of smart glass in its “Edge” tourist attraction, a glass cube that projects 3m out of the building and suspends visitors 300m over the city. The glass is opaque as the cube moves out over the edge of the building and becomes clear once fully extended.
First author Jaewon Kim, a PhD researcher in Applied Chemistry at RMIT, said the next steps in the research were developing precursors that will decompose at lower temperatures, allowing the coatings to be deposited on plastics and used in flexible electronics, as well as producing larger prototypes by scaling up the deposition.
“The spray coater we use can be automatically controlled and programmed, so fabricating bigger proof-of-concept panels will be relatively simple,” he said.
That is an impressive level of transparency. As per usual, here’s a link to and a citation for the paper (should you wish to explore further),
According to an August 4, 2020 news item on ScienceDaily the ‘Ice-phobic’ properties of moths’ eyes have inspired a new technology,
Researchers have been working for decades on improving the anti-icing performance of functional surfaces. Ice accumulation on aircraft wings, for instance, can reduce lifting force, block moving parts and cause disastrous problems.
Research in the journal AIP [American Institute of Physics] Advances, from AIP Publishing, investigates a unique nanostructure, modeled on moth eyes, that has anti-icing properties. Moth eyes are of interest because they have a distinct ice-phobic and transparent surface.
The researchers fabricated the moth eye nanostructure on a quartz substrate that was covered with a paraffin layer to isolate it from a cold and humid environment. Paraffin wax was chosen as a coating material due to its low thermal conductivity, easy coating and original water repellency.
“We evaluated the anti-icing properties of this unique nanostructure covered with paraffin in terms of adhesion strength, freezing time and mimicking rain sustainability,” said Nguyen Ba Duc, one of the authors.
Ice accumulation on energy transmission systems, vehicles and ships in a harsh environment often leads to massive destruction and contributes to serious accidents.
The researchers found the moth eyes nanostructure surface coated in paraffin exhibited greatly improved anti-icing performance, indicating the advantage of combining original water repellency and a unique heat-delaying structure. The paraffin interfered in the icing process in both water droplet and freezing rain experiments.
The number of air blocks trapped inside the nanostructure also contributed to delaying heat transfer, leading to an increase in freezing time of the attached water droplets.
“We also determined this unique nanostructure sample is suitable for optical applications, such as eyeglasses, as it has high transparency and anti-reflective properties,” said Ba Duc.
The high transparency and anti-reflective effects were due to the nanostructure being modeled on moth eyes, which have these transparent and anti-reflective properties.
As rainy season approaches in the Pacific Northwest of Canada and the US, there’s some good news about a sustainable water- and oil-repellent fabric. Sadly, it won’t be available this year but it’s something to look forward to.
An August 10, 2020 news item on phys.org announces the news from the University of British Columbia (UBC) about a greener, water-repellent fabric,
A sustainable, non-toxic and high-performance water-repellent fabric has long been the holy grail of outdoor enthusiasts and clothing companies alike. New research from UBC Okanagan and outdoor apparel giant Arc’teryx is making that goal one step closer to reality with one of the world’s first non-toxic oil and water-repellent performance textile finishes.
Outdoor fabrics are typically treated with perfluorinated compounds (PFCs) to repel oil and water. But according to Sadaf Shabanian, doctoral student at UBC Okanagan’s School of Engineering and study lead author, PFCs come with a number of problems.
“PFCs have long been the standard for stain repellents, from clothing to non-stick frying pans, but we know these chemicals have a detrimental impact on human health and the environment,” explains Shabanian. “They pose a persistent, long-term risk to health and the environment because they take hundreds of years to breakdown and linger both in the environment and our bodies.”
According to Mary Glasper, materials developer at Arc’teryx and collaborator on the project, these lasting impacts are one of the major motivations for clothing companies to seek out new methods to achieve the same or better repellent properties in their products.
To solve the problem, Shabanian and the research team added a nanoscopic layer of silicone to each fibre in a woven fabric, creating an oil-repellent jacket fabric that repels water, sweat and oils.
By understanding how the textile weave and fibre roughness affect the liquid interactions, Shabanian says she was able to design a fabric finish that did not use any PFCs.
“The best part of the new design is that the fabric finish can be made from biodegradable materials and can be recyclable,” she says. “It addresses many of the issues related to PFC-based repellent products and remains highly suitable for the kind of technical apparel consumers and manufacturers are looking for.”
Arc’teryx is excited about the potential of this solution.
“An oil- and water-repellent finish that doesn’t rely on PFCs is enormously important in the world of textiles and is something the whole outdoor apparel industry has been working on for years,” says Glasper. “Now that we have a proof-of-concept, we’ll look to expand its application to other DWR-treated textiles used in our products and to improve the durability of the treatment.”
Kevin Golovin, principal investigator of the Okanagan Polymer Engineering Research & Applications Lab where the research was done, says the new research is important because it opens up a new area of green textile manufacturing.
He explains that while the new technology has immense potential, there are still several more years of development and testing needed before people will see fabrics with this treatment in stores.
“Demonstrating oil repellency without the use of PFCs is a critical first step towards a truly sustainable fabric finish,” says Golovin. “And it’s something previously thought impossible.”
The research is funded through a grant from the Natural Sciences and Engineering Research Council of Canada (NSERC), with support from Arc’teryx Equipment Inc.
A research team led by UCLA materials scientists has demonstrated ways to make super white paint that reflects as much as 98% of incoming heat from the sun. The advance shows practical pathways for designing paints that, if used on rooftops and other parts of a building, could significantly reduce cooling costs, beyond what standard white ‘cool-roof’ paints can achieve.
The findings, published online in Joule, are a major and practical step towards keeping buildings cooler by passive daytime radiative cooling — a spontaneous process in which a surface reflects sunlight and radiates heat into space, cooling down to potentially sub-ambient temperatures. This can lower indoor temperatures and help cut down on air conditioner use and associated carbon dioxide emissions.
“When you wear a white T-shirt on a hot sunny day, you feel cooler than if you wore one that’s darker in color — that’s because the white shirt reflects more sunlight and it’s the same concept for buildings,” said Aaswath Raman, an assistant professor of materials science and engineering at UCLA Samueli School of Engineering, and the principal investigator on the study. “A roof painted white will be cooler inside than one in a darker shade. But those paints also do something else: they reject heat at infrared wavelengths, which we humans cannot see with our eyes. This could allow buildings to cool down even more by radiative cooling.”
The best performing white paints currently available typically reflect around 85% of incoming solar radiation. The remainder is absorbed by the chemical makeup of the paint. The researchers showed that simple modifications in a paint’s ingredients could offer a significant jump, reflecting as much as 98% of incoming radiation.
Current white paints with high solar reflectance use titanium oxide. While the compound is very reflective of most visible and near-infrared light, it also absorbs ultraviolet and violet light. The compound’s UV absorption qualities make it useful in sunscreen lotions, but they also lead to heating under sunlight – which gets in the way of keeping a building as cool as possible.
The researchers examined replacing titanium oxide with inexpensive and readily available ingredients such as barite, which is an artist’s pigment, and pow[d]ered polytetrafluoroethylene, better known as Teflon. These ingredients help paints reflect UV light. The team also made further refinements to the paint’s formula, including reducing the concentration of polymer binders, which also absorb heat.
“The potential cooling benefits this can yield may be realized in the near future because the modifications we propose are within the capabilities of the paint and coatings industry,” said UCLA postdoctoral scholar Jyotirmoy Mandal, a Schmidt Science Fellow working in Raman’s research group and the co-corresponding author on the research.
Beyond the advance, the authors suggested several long-term implications for further study, including mapping where such paints could make a difference, studying the effect of pollution on radiative cooling technologies, and on a global scale, if they could make a dent on the earth’s own ability to reflect heat from the sun.
The researchers also noted that many municipalities and governments, including the state of California and New York City, have started to encourage cool-roof technologies for new buildings.
“We hope that the work will spur future initiatives in super-white coatings for not only energy savings in buildings, but also mitigating the heat island effects of cities, and perhaps even showing a practical way that, if applied on a massive, global scale could affect climate change,” said Mandal, who has studied cooling paint technologies for several years. “This would require a collaboration among experts in diverse fields like optics, materials science and meteorology, and experts from the industry and policy sectors.”
Here’s a link (also in the news release) to and a citation for the paper,
Canada’s stores of fresh water are not as plentiful as once thought, and threaten to pinch the economy and pit provinces against each other, a federal document says.
An internal report drafted last December  by Environment Canada warns that climate change and a growing population will further drain resources.
“We can no longer take our extensive water supplies for granted,” says the report, titled A Federal Perspective on Water Quantity Issues.
The Canadian Press obtained the 21-page draft report under the Access to Information Act.
It suggests the federal government take a more hands-on role in managing the country’s water, which is now largely done by the provinces. Ottawa still manages most of the fresh water in the North through water boards.
The Conservatives promised a national water strategy in last fall’s throne speech but have been criticized since for announcing only piecemeal projects.
The Tories, like the previous Liberal government, are also behind in publishing annual reports required by law that show how water supplies are used and maintained.
The last assessment posted on Environment Canada’s website is from 2005-06.
The internal draft report says the government currently does not know enough about the country’s water to properly manage it.
‘This is not a crisis yet. Why would we expect any government, regardless of political leaning or level, to do anything about it?’
“Canada lacks sound information at a national scale on the major uses and user[s] of water,” it says.
“National forecasting of water availability has never been done because traditionally our use of the resource was thought to be unlimited.”
Canada has a fifth of the world’s supply of fresh water, but only seven per cent of it is renewable. The rest comes from ice-age glaciers and underground aquifers.
One per cent of Canada’s total water supply is renewed each year by precipitation, the report says.
Moreover, government data on the country’s groundwater reserves is deemed “sparse and often inadequate.”
That’s in contrast to the United States, which has spent more than a decade mapping its underground water reserves. Canada shares aquifers with the U.S., and the report says: “Our lack of data places Canada at strategic disadvantage for bilateral negotiations with the U.S.”
A comprehensive review [World Wildlife Federation: a national assessment of of Canada’s freshwater Watershed Reports; 2017] freshwater ecosystems reveals rising threats from pollution, overuse, invasive species and climate change among other problems. Yet, the biggest threat of all may be a lack of information that hinders effective regulation, Ivan Semeniuk reports. …
Some of that information may be out of date.
Getting back on topic, here’s one possible solution to better managing our use of water.
Every day, more than 141 billion liters of water are used solely to flush toilets. With millions of global citizens experiencing water scarcity, what if that amount could be reduced by 50%?
The possibility may exist through research conducted at Penn State, released today (Nov. 18) in Nature Sustainability.
“Our team has developed a robust bio-inspired, liquid, sludge- and bacteria-repellent coating that can essentially make a toilet self-cleaning,” said Tak-Sing Wong, Wormley Early Career Professor of Engineering and associate professor of mechanical engineering and biomedical engineering.
In the Wong Laboratory for Nature Inspired Engineering, housed within the Department of Mechanical Engineering and the Materials Research Institute, researchers have developed a method that dramatically reduces the amount of water needed to flush a conventional toilet, which usually requires 6 liters.
Co-developed by Jing Wang, a doctoral graduate from Wong’s lab, the liquid-entrenched smooth surface (LESS) coating is a two-step spray that, among other applications, can be applied to a ceramic toilet bowl. The first spray, created from molecularly grafted polymers, is the initial step in building an extremely smooth and liquid-repellent foundation.
“When it dries, the first spray grows molecules that look like little hairs, with a diameter of about 1,000,000 times thinner than a human’s,” Wang said.
While this first application creates an extremely smooth surface as is, the second spray infuses a thin layer of lubricant around those nanoscopic “hairs” to create a super-slippery surface.
“When we put that coating on a toilet in the lab and dump synthetic fecal matter on it, it (the synthetic fecal matter) just completely slides down and nothing sticks to it (the toilet),” Wang said.
With this novel slippery surface, the toilets can effectively clean residue from inside the bowl and dispose of the waste with only a fraction of the water previously needed. The researchers also predict the coating could last for about 500 flushes in a conventional toilet before a reapplication of the lubricant layer is needed.
While other liquid-infused slippery surfaces can take hours to cure, the LESS two-step coating takes less than five minutes. The researcher’s experiments also found the surface effectively repelled bacteria, particularly ones that spread infectious diseases and unpleasant odors.
If it were widely adopted in the United States, it could direct critical resources toward other important activities, to drought-stricken areas or to regions experiencing chronic water scarcity, said the researchers.
Driven by these humanitarian solutions, the researchers also hope their work can make an impact in the developing world. The technology could be used within waterless toilets, which are used extensively around the world.
“Poop sticking to the toilet is not only unpleasant to users, but it also presents serious health concerns,” Wong said.
However, if a waterless toilet or urinal used the LESS coating, the team predicts these types of fixtures would be more appealing and safer for widespread use.
To address these issues in both the United States and around the world, Wong and his collaborators, Wang, Birgitt Boschitsch, and Nan Sun, all mechanical engineering alumni, began a start-up venture.
With support from the Ben Franklin Technology Partners’ TechCelerator, the National Science Foundation, the Department of Energy, the Office of Naval Research, the Rice Business Plan Competition and Y-Combinator, their company, spotLESS Materials, is already bringing the LESS coating to market.
“Our goal is to bring impactful technology to the market so everyone can benefit,” Wong said. “To maximize the impact of our coating technology, we need to get it out of the lab.”
Looking forward, the team hopes spotLESS Materials will play a role in sustaining the world’s water resources and continue expanding the reach of their technology.
“As a researcher in an academic setting, my goal is to invent things that everyone can benefit from,” Wong said. “As a Penn Stater, I see this culture being amplified through entrepreneurship, and I’m excited to contribute.”
This paper is behind a paywall. However, the researchers have made a brief video available,
There you have it. One random thought, that toilet image reminded me of the controversy over Marcel Duchamp, the Fountain, and who actually submitted a urinal for consideration as a piece of art (Jan. 23, 2019 posting). Hint: Some believe it was Baroness Elsa von Freytag-Loringhoven.
There’s a very good November 11, 2019 article by Natalie Angier for the New York Times on carbon nanotubes (CNTs) and the colour black,
On a laboratory bench at the National Institute of Standards and Technology was a square tray with two black disks inside, each about the width of the top of a Dixie cup. Both disks were undeniably black, yet they didn’t look quite the same.
Solomon Woods, 49, a trim, dark-haired, soft-spoken physicist, was about to demonstrate how different they were, and how serenely voracious a black could be.
“The human eye is extraordinarily sensitive to light,” Dr. Woods said. Throw a few dozen photons its way, a few dozen quantum-sized packets of light, and the eye can readily track them.
Dr. Woods pulled a laser pointer from his pocket. “This pointer,” he said, “puts out 100 trillion photons per second.” He switched on the laser and began slowly sweeping its bright beam across the surface of the tray.
On hitting the white background, the light bounced back almost unimpeded, as rude as a glaring headlight in a rearview mirror.
The beam moved to the first black disk, a rondel of engineered carbon now more than a decade old. The light dimmed significantly, as a sizable tranche of the incident photons were absorbed by the black pigment, yet the glow remained surprisingly strong.
Finally Dr. Woods trained his pointer on the second black disk, and suddenly the laser’s brilliant beam, its brash photonic probe, simply — disappeared. Trillions of light particles were striking the black disk, and virtually none were winking back up again. It was like watching a circus performer swallow a sword, or a husband “share” your plate of French fries: Hey, where did it all go?
N.I.S.T. disk number two was an example of advanced ultra-black technology: elaborately engineered arrays of tiny carbon cylinders, or nanotubes, designed to capture and muzzle any light they encounter. Blacker is the new black, and researchers here and abroad are working to create ever more efficient light traps, which means fabricating materials that look ever darker, ever flatter, ever more ripped from the void.
The N.I.S.T. ultra-black absorbs at least 99.99 percent of the light that stumbles into its nanotube forest. But scientists at the Massachusetts Institute of Technology reported in September the creation of a carbon nanotube coating that they claim captures better than 99.995 of the incident light.
… The more fastidious and reliable the ultra-black, the more broadly useful it will prove to be — in solar power generators, radiometers, industrial baffles and telescopes primed to detect the faintest light fluxes as a distant planet traverses the face of its star.
Psychology and metaphors
It’s not all technical, Angier goes on to mention the psychological and metaphorical aspects,
Psychologists have gathered evidence that black is among the most metaphorically loaded of all colors, and that we absorb our often contradictory impressions about black at a young age.
Reporting earlier this year in the Quarterly Journal of Experimental Psychology, Robin Kramer and Joanne Prior of the University of Lincoln in the United Kingdom compared color associations in a group of 104 children, aged 5 to 10, with those of 100 university students.
The researchers showed subjects drawings in which a lineup of six otherwise identical images differed only in some aspect of color. The T-shirt of a boy taking a test, for example, was switched from black to blue to green to red to white to yellow. The same for a businessman’s necktie, a schoolgirl’s dress, a dog’s collar, a boxer’s gloves.
Participants were asked to link images with traits. Which boy was likeliest to cheat on the test? Which man was likely to be in charge at work? Which girl was the smartest in her class, which dog the scariest?
Again and again, among both children and young adults, black pulled ahead of nearly every color but red. Black was the color of cheating, and black was the color of cleverness. A black tie was the mark of a boss, a black collar the sign of a pit bull. Black was the color of strength and of winning. Black was the color of rage.
Then, there is the world of art,
For artists, black is basal and nonnegotiable, the source of shadow, line, volume, perspective and mood. “There is a black which is old and a black which is fresh,” Ad Reinhardt, the abstract expressionist artist, said. “Lustrous black and dull black, black in sunlight and black in shadow.”
So essential is black to any aesthetic act that, as David Scott Kastan and Stephen Farthing describe in their scholarly yet highly entertaining book, “On Color,” modern artists have long squabbled over who pioneered the ultimate visual distillation: the all-black painting.
Was it the Russian Constructivist Aleksandr Rodchenko, who in 1918 created a series of eight seemingly all-black canvases? No, insisted the American artist Barnett Newman: Those works were very dark brown, not black. He, Mr. Newman, deserved credit for his 1949 opus, “Abraham,” which in 1966 he described as “the first and still the only black painting in history.”
But what about Kazimir Malevich’s “Black Square” of 1915? True, it was a black square against a white background, but the black part was the point. Then again, the English polymath Robert Fludd had engraved a black square in a white border back in 1617.
Clearly, said Alfred H. Barr, Jr., the first director of the Museum of Modern Art, “Each generation must paint its own black square.”
Solomon and his NIST colleagues and the MIT scientists are all trying to create materials with structural colour, in this case, black. Angier goes on to discuss structural colour in nature mentioning bird feathers and spiders as examples of where you might find superblacks. For anyone unfamiliar with structural colour, the colour is not achieved with pigment or dye but with tiny structures, usually measured at the nanoscale, on a bird’s wing, a spider’s belly, a plant leaf, etc. Structural colour does not fade or change . Still, it’s possible to destroy the structures, i.e., the colour, but light and time will not have any effect since it’s the tiny structures and their optical properties which are producing the colour . (Even after all these years, my favourite structural colour story remains a Feb. 1, 2013 article, Color from Structure, by Cristina Luiggi for The Scientist magazine. For a shorter version, I excerpted parts of Luiggi’s story for my February 7, 2013 posting.)
The examples of structural colour in Angier’s article were new to me. However, there are many, many examples elsewhere,. You can find some here by using the terms ‘structural colour’ or ‘structural color’ in the blog’s search engine.
Angier’s is a really good article and I strongly recommend reading it if you have time but I’m a little surprised she doesn’t mention Vantablack and the artistic feud. More about that in a moment,
Massachusetts Institute of Technology and a ‘blacker black’
According to MIT (Massachusetts Institute of Technology), they have the blackest black. It too is courtesy of carbon nanotubes.
What you see in the above ‘The Redemption of Vanity’ was on show at the New York Stock Exchange (NYSE) from September 13 – November 29, 2019. It’s both an art piece and a demonstration of MIT’s blackest black.
With apologies to “Spinal Tap,” it appears that black can, indeed, get more black.
MIT engineers report today that they have cooked up a material that is 10 times blacker than anything that has previously been reported. The material is made from vertically aligned carbon nanotubes, or CNTs — microscopic filaments of carbon, like a fuzzy forest of tiny trees, that the team grew on a surface of chlorine-etched aluminum foil. The foil captures at least 99.995 percent* of any incoming light, making it the blackest material on record.
The researchers have published their findings today in the journal ACS-Applied Materials and Interfaces. They are also showcasing the cloak-like material as part of a new exhibit today at the New York Stock Exchange, titled “The Redemption of Vanity.”
The artwork, conceived by Diemut Strebe, an artist-in-residence at the MIT Center for Art, Science, and Technology, in collaboration with Brian Wardle, professor of aeronautics and astronautics at MIT, and his group, and MIT Center for Art, Science, and Technology artist-in-residence Diemut Strebe, features a 16.78-carat natural yellow diamond from LJ West Diamonds, estimated to be worth $2 million, which the team coated with the new, ultrablack CNT material. The effect is arresting: The gem, normally brilliantly faceted, appears as a flat, black void.
Wardle says the CNT material, aside from making an artistic statement, may also be of practical use, for instance in optical blinders that reduce unwanted glare, to help space telescopes spot orbiting exoplanets.
“There are optical and space science applications for very black materials, and of course, artists have been interested in black, going back well before the Renaissance,” Wardle says. “Our material is 10 times blacker than anything that’s ever been reported, but I think the blackest black is a constantly moving target. Someone will find a blacker material, and eventually we’ll understand all the underlying mechanisms, and will be able to properly engineer the ultimate black.”
Wardle’s co-author on the paper is former MIT postdoc Kehang Cui, now a professor at Shanghai Jiao Tong University.
Into the void
Wardle and Cui didn’t intend to engineer an ultrablack material. Instead, they were experimenting with ways to grow carbon nanotubes on electrically conducting materials such as aluminum, to boost their electrical and thermal properties.
But in attempting to grow CNTs on aluminum, Cui ran up against a barrier, literally: an ever-present layer of oxide that coats aluminum when it is exposed to air. This oxide layer acts as an insulator, blocking rather than conducting electricity and heat. As he cast about for ways to remove aluminum’s oxide layer, Cui found a solution in salt, or sodium chloride.
At the time, Wardle’s group was using salt and other pantry products, such as baking soda and detergent, to grow carbon nanotubes. In their tests with salt, Cui noticed that chloride ions were eating away at aluminum’s surface and dissolving its oxide layer.
“This etching process is common for many metals,” Cui says. “For instance, ships suffer from corrosion of chlorine-based ocean water. Now we’re using this process to our advantage.”
Cui found that if he soaked aluminum foil in saltwater, he could remove the oxide layer. He then transferred the foil to an oxygen-free environment to prevent reoxidation, and finally, placed the etched aluminum in an oven, where the group carried out techniques to grow carbon nanotubes via a process called chemical vapor deposition.
By removing the oxide layer, the researchers were able to grow carbon nanotubes on aluminum, at much lower temperatures than they otherwise would, by about 100 degrees Celsius. They also saw that the combination of CNTs on aluminum significantly enhanced the material’s thermal and electrical properties — a finding that they expected.
What surprised them was the material’s color.
“I remember noticing how black it was before growing carbon nanotubes on it, and then after growth, it looked even darker,” Cui recalls. “So I thought I should measure the optical reflectance of the sample.
“Our group does not usually focus on optical properties of materials, but this work was going on at the same time as our art-science collaborations with Diemut, so art influenced science in this case,” says Wardle.
Wardle and Cui, who have applied for a patent on the technology, are making the new CNT process freely available to any artist to use for a noncommercial art project.
“Built to take abuse”
Cui measured the amount of light reflected by the material, not just from directly overhead, but also from every other possible angle. The results showed that the material absorbed at least 99.995 percent of incoming light, from every angle. In other words, it reflected 10 times less light than all other superblack materials, including Vantablack. If the material contained bumps or ridges, or features of any kind, no matter what angle it was viewed from, these features would be invisible, obscured in a void of black.
The researchers aren’t entirely sure of the mechanism contributing to the material’s opacity, but they suspect that it may have something to do with the combination of etched aluminum, which is somewhat blackened, with the carbon nanotubes. Scientists believe that forests of carbon nanotubes can trap and convert most incoming light to heat, reflecting very little of it back out as light, thereby giving CNTs a particularly black shade.
“CNT forests of different varieties are known to be extremely black, but there is a lack of mechanistic understanding as to why this material is the blackest. That needs further study,” Wardle says.
The material is already gaining interest in the aerospace community. Astrophysicist and Nobel laureate John Mather, who was not involved in the research, is exploring the possibility of using Wardle’s material as the basis for a star shade — a massive black shade that would shield a space telescope from stray light.
“Optical instruments like cameras and telescopes have to get rid of unwanted glare, so you can see what you want to see,” Mather says. “Would you like to see an Earth orbiting another star? We need something very black. … And this black has to be tough to withstand a rocket launch. Old versions were fragile forests of fur, but these are more like pot scrubbers — built to take abuse.”
[Note] An earlier version of this story stated that the new material captures more than 99.96 percent of incoming light. That number has been updated to be more precise; the material absorbs at least 99.995 of incoming light.
Here’s an August 29, 2019 news release from MIT announcing the then upcoming show. Usually I’d expect to see a research paper associated with this work but this time it seems to an art exhibit only,
The MIT Center for Art, Science &Technology (CAST) and the New York Stock Exchange (NYSE) will present The Redemption of Vanity,created by artist Diemut Strebe in collaboration with MIT scientist Brian Wardle and his lab, on view at the New York Stock Exchange September 13, 2019 -November 25, 2019. For the work, a 16.78 carat natural yellow diamond valued at $2 million from L.J.West was coated using a new procedure of generating carbon nanotubes (CNTs), recently measured to be the blackest black ever created, which makes the diamond seem to disappear into an invisible void. The patented carbon nanotube technology (CNT) absorbs more than 99.96% of light and was developed by Professor Wardle and his necstlablab at MIT.
“Any object covered with this CNT material loses all its plasticity and appears entirely flat, abbreviated/reduced to a black silhouette. In outright contradiction to this we see that a diamond,while made of the very same element (carbon) performs the most intense reflection of light on earth.Because of the extremely high light absorbtive qualities of the CNTs, any object, in this case a large diamond coated with CNT’s, becomes a kind of black hole absent of shadows,“ explains Strebe.“The unification of extreme opposites in one object and the particular aesthetic features of the CNTs caught my imagination for this art project.”
“Strebe’s art-science collaboration caused us to look at the optical properties of our new CNT growth, and we discovered that these particular CNTs are blacker than all other reported materials by an order of magnitude across the visible spectrum”, says Wardle. The MIT team is offering the process for any artist to use. “We do not believe in exclusive ownership of any material or idea for any artwork and have opened our method to any artist,” say Strebe and Wardle.“
The project explores material and immaterial value attached to objects and concepts in reference to luxury, society and to art. We are presenting the literal devaluation of a diamond, which is highly symbolic and of high economic value.It presents a challenge to art market mechanisms on the one hand, while expressing at the same time questions of the value of art in a broader way. In this sense it manifests an inquiry into the significance of the value of objects of art and the art market,” says Strebe. “We are honored to present this work at The New York Stock Exchange, which I believe to be a most fitting location to consider the ideas embedded in The Redemption of Vanity.”
“The New York Stock Exchange, a center of financial and technological innovation for 227 years, is the perfect venue to display Diemut Strebe and Professor Brian Wardle’s collaboration. Their work brings together cutting-edge nanotube technology and a natural diamond, which is a symbol of both value and longevity,” said John Tuttle, NYSE Group Vice Chairman & Chief Commercial Officer.
“We welcome all scientists and artists to venture into the world of natural color diamonds. The Redemption of Vanity exemplifies the bond between art, science, and luxury. The 16-carat vivid yellow diamond in the exhibit spent millions of years in complete darkness, deep below the earth’s surface. It was only recently unearthed —a once-in-a-lifetime discovery of exquisite size and color. Now the diamond will relive its journey to darkness as it is covered in the blackest of materials. Once again, it will become a reminder that something rare and beautiful can exist even in darkness,”said Larry West.
The “disappearing” diamond in The Redemption of Vanity is a $2 Million Fancy Vivid Yellow SI1 (GIA), Radiant shape, from color diamond specialist, L.J. West Diamonds Inc. of New York.
The Redemption of Vanity, conceived by Diemut Strebe, has been realized with Brian L. Wardle, Professor of Aeronautics and Astronautics and Director of necstlab and Nano-Engineered Composite aerospace STructures (NECST) Consortium and his team Drs. Luiz Acauan and Estelle Cohen, in conjunction with Strebe’s residency at MIT supported by the Center for Art, Science & Technology (CAST).
ABOUT THE ARTISTS
Diemut Strebe is a conceptual artist based in Boston, MA and a MIT CAST Visiting Artist. She has collaborated with several MIT faculty, including Noam Chomsky and Robert Langer on Sugababe (2014), Litmus (2014) and Yeast Expression(2015); Seth Lloyd and Dirk Englund on Wigner’s Friends(2014); Alan Guth on Plötzlich! (2018); researchers in William Tisdale’s Lab on The Origin of the Works of Art(2018); Regina Barzilay and Elchanan Mossel on The Prayer (2019); and Ken Kamrin and John Brisson on The Gymnast (2019). Strebe is represented by the Ronald Feldman Gallery.
Brian L. Wardle is a Professor of Aeronautics and Astronautics at MIT and the director of the necstlab research group and MIT’s Nano-Engineered Composite aerospace STructures (NECST) Consortium. Wardle previously worked with CAST Visiting Artist Trevor Paglen on The Last Picturesproject (2012).
ABOUT THE MIT CENTER FOR ART, SCIENCE & TECHNOLOGY
A major cross-school initiative, the MIT Center for Art, Science & Technology (CAST) creates new opportunities for art, science and technology to thrive as interrelated, mutually informing modes of exploration, knowledge and discovery. CAST’s multidisciplinary platform presents performing and visual arts programs, supports research projects for artists working with science and engineering labs, and sponsors symposia, classes, workshops, design studios, lectures and publications. The Center is funded in part by a generous grant from the Andrew W. Mellon Foundation. Evan Ziporyn is the Faculty Director and Leila W. Kinney is the Executive Director.Since its inception in 2012, CAST has been the catalyst for more than 150 artist residencies and collaborative projects with MIT faculty and students, including numerous cross-disciplinary courses, workshops, concert series, multimedia projects, lectures and symposia. The visiting artists program is a cornerstone of CAST’s activities, which encourages cross-fertilization among disciplines and intensive interaction with MIT’s faculty and students. More info at https://arts.mit.edu/cast/ .
HISTORY OF VISITING ARTISTS AT MIT
Since the late 1960s, MIT has been a leader in integrating the arts and pioneering a model for collaboration among artists, scientists and engineers in a research setting. CAST’s Visiting Artists Program brings internationally acclaimed artists to engage with MIT’s creative community in ways that are mutually enlightening for the artists and for faculty, students and research staff at the Institute. Artists who have worked extensively at MIT include Mel Chin, Olafur Eliasson, Rick Lowe, Vik Muniz, Trevor Paglen, Tomás Saraceno, Maya Beiser, Agnieszka Kurant, and Anicka Yi.
ABOUT L.J. WEST DIAMONDS
L.J. West Diamonds is a three generation natural color diamond whole sale rfounded in the late 1970’s by Larry J. West and based in New York City. L.J. West has established itself as one of the world’s prominent houses for some of the most rare and important exotic natural fancy color diamonds to have ever been unearthed. This collection includes a vast color spectrum of rare pink, blue, yellow, green, orange and red diamonds. L.J. West is an expert in every phase of the jewelry process –from sourcing to the cutting, polishing and final design. Each exceptional jewel is carefully set to become a unique work of art.The Redemption of Vanity is on view at the New York Stock Exchange by appointment only.
Press viewing: September 13, 2019 at 3pmNew York Stock Exchange, 11 Wall Street, New York, NY 10005RSVP required. Please check-in at the blue tent at 2 Broad Street(at the corner of Wall and Broad Streets). All guests are required to show a government issued photo ID and go through airport-like security upon entering the NYSE.NYSE follows a business casual dress code -jeans & sneakers are not permitted.
No word yet if there will be other showings.
An artistic feud (of sorts)
Earlier this year, I updated a story on Vantablack. It was the blackest black, blocking 99.8% of light when I featured it in a March 14, 2016 posting. The UK company making the announcement, Surrey NanoSystems, then laid the groundwork for an artistic feud when it granted exclusive rights to their carbon nanotube-based coating, Vantablack, to Sir Anish Kapoor mentioned here in an April 16, 2016 posting.
This exclusivity outraged some artists notably, Stuart Semple. In his first act of defiance, he created the pinkest pink. Next, came a Kickstarter campaign to fund Semple’s blackest black, which would be available to all artists except Anish Kapoor. You can read all about the pinkest pink and blackest black as per Semple in my February 21, 2019 posting. You can also get a bit of an update in an Oct. 17, 2019 Stuart Semple proffile by Berenice Baker for Verdict,
… so I managed to hire a scientist, Jemima, to work in the studio with me. She got really close to a super black, and we made our own pigment to this recipe and it was awesome, but we couldn’t afford to put it into manufacture because it cost £25,000.”
Semple launched a Kickstarter campaign and was amazed to raise half a million pounds, making it the second most-supported art Kickstarter of all time.
The ‘race to the blackest’ is well underway, with MIT researchers recently announcing a carbon nanotube-based black whose light absorption they tested by coasting a diamond. But Semple is determined that his black should be affordable by all artists and work like a paint, not only perform in laboratory conditions. He’s currently working with Jemima and two chemists to upgrade the recipe for Black 3.2.
I don’t know how Semple arrived at his blackest black. I think it’s unlikely that he achieved the result by working with carbon nanotubes since my understanding is that CNTs aren’t that easy to produce.
Interesting, eh? In just a few years scientists have progressed from achieving a 99.8% black to 99.999%. It doesn’t seem like that big a difference to me but with Solomon Woods, at the beginning of this post, making the point that our eyes are very sensitive to light, an artistic feud, and a study uncovering deep emotions, getting the blackest black is a much more artistically fraught endeavour than I had imagined.
I’m getting to the science but first this video of what looks like jiggling jello,
In actuality, it’s a superhydrophobic coating demonstration and a July 2, 2019 news item on phys.org provides more information,
Plant leaves have a natural superpower—they’re designed with water repelling characteristics. Called a superhydrophobic surface, this trait allows leaves to cleanse themselves from dust particles. Inspired by such natural designs, a team of researchers at Texas A&M University has developed an innovative way to control the hydrophobicity of a surface to benefit to the biomedical field.
Researchers in Dr. Akhilesh K. Gaharwar’s lab in the Department of Biomedical Engineering have developed a “lotus effect” by incorporating atomic defects in nanomaterials, which could have widespread applications in the biomedical field including biosensing, lab-on-a-chip, blood-repellent, anti-fouling and self-cleaning applications.
Superhydrophobic materials are used extensively for self-cleaning characteristic of devices. However, current materials require alteration to the chemistry or topography of the surface to work. This limits the use of superhydrophobic materials.
“Designing hydrophobic surfaces and controlling the wetting behavior has long been of great interest, as it plays crucial role in accomplishing self-cleaning ability,” Gaharwar said. “However, there are limited biocompatible approach to control the wetting behavior of the surface as desired in several biomedical and biotechnological applications.”
The Texas A&M design adopts a ‘nanoflower-like’ assembly of two-dimensional (2D) atomic layers to protect the surface from wetting. The team recently released a study published in Chemical Communications. 2D nanomaterials are an ultrathin class of nanomaterials and have received considerable attention in research. Gaharwar’s lab used 2D molybdenum disulfide (MoS2), a new class of 2D nanomaterials that has shown enormous potential in nanoelectronics, optical sensors, renewable energy sources, catalysis and lubrication, but has not been investigated for biomedical applications. This innovative approach demonstrates applications of this unique class of materials to the biomedical industry.
“These 2D nanomaterials with their hexagonal packed layer repel water adherence, however, a missing atom from the top layer can allow easy access to water molecules by the next layer of atoms underneath making it transit from hydrophobic to hydrophilic,” said lead author of the study, Dr. Manish Jaiswal, a senior research associate in Gaharwar’s lab.
This innovative technique opens many doors for expanded applications in several scientific and technological areas. The superhydrophobic coating can be easily applied over various substrates such as glass, tissue paper, rubber or silica using the solvent evaporation method. These superhydrophobic coatings have wide-spread applications, not only in developing self-cleaning surfaces in nanoelectronics devices, but also for biomedical applications.
Specifically, the study demonstrated that blood and cell culture media containing proteins do not adhere to the surface, which is very promising. In addition, the team is currently exploring the potential applications of controlled hydrophobicity in stem cell fate.