The Magic of Nano-Surface Engineering
Min Zou: Thank you for having me, it’s a pleasure to be here.
MM: I look back and realize that I’ve been writing about your work for about 15 years. That’s almost the entire time I’ve been here. It’s probably too much to try to cover everything that you’ve accomplished over that span and longer, because you’ve been here 19 years, but I would like to go back to the beginning and have you defined two big words, as they relate to the essence, I guess, and longevity of your work. I’m going to try to pronounce them. One is hydrophobicity, and the other one is polytetrafluoroethylene. I think I got that right. What are these and tell us how they are part of your research.
MZ: We’ll start with the word hydrophobicity. Hydro comes from Greek hydor which means water, and phobia comes Greek fobus, which means fear. So, hydrophobicity means fear of water or lack of affinity to water. It is an often-used word in the scientific community to define surface wettability. Surface hydrophobicity is often quantified by the water contact angle, which is angle between the water solid interface and water air interface. If this angle is greater than 90 degrees, the surface is called hydrophobic. If this angle is greater than 150 degrees, the surface is called superhydrophobic. So, hydrophobic surfaces have many practical applications such as self-cleaning, anti-icing and anti-corrosion. For a surface to have superhydrophobic properties, both surface micro- nano-topography and low-surface-energy chemistries are required. My lab has developed several techniques to fabricate various micro- nano-topographies and low-surface-energy coatings such as polytetrafluoroethylene, or PTFE coatings, for generating superior phobic surfaces.
MM: If I could interrupt you there, that was a big relief, you’re having trouble pronouncing it yourself after all these years. So I don’t feel so bad.
MZ: Yeah, polytetrafluoroethylene.
MM: PTFE, tell us what that is.
MZ: Yeah, PTFE is a fluoro-carbon-based polymer, consisting, of course, of carbon and fluorine atoms. Carbons form twisted… slightly twisted chains. Each carbon atom is connected to fluorine atoms. They have very low surface energy, and the PTFE is better known for its brand name Teflon, which is widely used in cookware for its non-stick properties. However, there are many other desirable properties, such as low coefficient friction or slippery. Slippery means low-surface energy and hydrophobicity, like we mentioned, high temperature resistance and chemical resistance. So, in addition, PTFE is also biocompatible, so it finds applications in biomedical implants as well as well as regular machineries like self-lubricating bearings, self-cleaning surfaces. So there are lots of applications of PTFE. However, one big challenge of applying PTFE coating is that it’s nonstick, so therefore it’s hard to stick to a substrate. Our lab has developed novel technologies to strongly adhere PTFE to a substrate, enable its durability and longevity.
MM: In 2015, you and several colleagues received a $24 million… sorry, $24 million in NSF EPSCOR funds to create the Center for Advanced Surface Engineering. Can you talk about this center? What? What do you do there? What do the researchers do at this center?
MZ: Yes, the center brought together 10 universities in the state of Arkansas involving faculty, postdoctoral fellows and students working on developing new materials and surfaces with multi-functionalities and tunabilities. There are four main research thrusts for creating novel surfaces. The focus on mechanical is one thrust, optical is another, cellulosic and biomedical medical applications, that’s the other thrust. So there are total four research thrusts. And the center research is highly interdisciplinary, involving various engineering discipline like mechanical, chemical, biological, as well as physics, chemistry, biology, nanotechnology, material sciences. So there are different disciplines working together and come up with solutions to create surfaces that has potential applications. The center involves more than 60 faculty members, 90 graduate students and 10 post-doc fellows, and over 100 students have participated in the center research. And the researchers develop new technologies to make novel nanoparticles, two-dimensional materials, engineering surface with special properties, such as the superhydrophobic facility that we mentioned, as well as oil felicity, which means oil-absorbing capability. This is very useful in like oil spill cleaning. And as well as, of course, reduced friction… surface with reduced friction and longer durability and anti-microbial properties and many other properties that can impact manufacturing, health care and environment. We also developed several new models that can model new materials, nanomaterials, cellulosic materials, coatings, and engineered surfaces. Overall, the center helped to improve the research competitiveness of the state of Arkansas in the field of material science and engineering, and we continue to impact major industry sectors.
MM: The more recent worked with a newer NSF grant, 500… half a million dollars to develop graphite lubricant coatings for conveyor belts, industrial conveyor systems. Tell us about that project.
MZ: Yeah, so in this project we’ll partner with industry leaders to develop low friction and durable graphite coatings, called solid lubricant, for belt conveyor systems. Belt conveyors are widely used in many industries. You can imagine the airport, the distribution centers, FedEx and UPS. And they are the fastest growing conveyor type. The global conveyor market is more than $5 billion per year and flat conveyor market is like 26 percent more than 26 percent of this. However, they are not necessarily energy efficient. About 60 percent of the total energy in a flat conveyor system is used to overcome friction, sliding friction between the belt and the sliding bed. So our goal is to be able to reduce that friction and improve the energy efficiency.
MM: One of the exciting stories of your research here, your tenure at the University of Arkansas, is tech transfer. Out of these EPSCoR funds, NSF EPSCoR funds, there have been at least two companies that have been created because of because of… really based on your research. SurfTec is one and WattGlass? I and some of my colleagues have written about these. Can you tell us about these companies and how they were created out of your work?
MZ: Yeah, so first I would like to mention that I have very talented and hard-working students who are dedicated to the commercialization of technologies. So both SurfTec and WattGlass were co-founded by my former PhD students to commercialize the technologies. They worked on during their PhD dissertation in in my lab. SurfTec started with the commercialization effort by securing funding from the NSF, National Science Foundation and Department of Energy to develop durable PTFE coating for bearing applications, based on my student Samuel Bedford’s PhD research. They are now expanded the technology portfolio to anti-icing and ice-phobic coatings that could have many applications. For example, you know, I think coatings could help prevent devastating disasters caused by the ice creation on the power generation system, like the one we have… the damage caused by the Texas ice storm last year. And, of course, there are other applications as well. And they also developed lubricant sprays for industrial applications and ski wax for consumer applications. Yeah, so an earlier company, WattGlass, is also started with the commercialization effort based on Corey Thompson’s PhD research. And he secured the funding from the National Science Foundation and DoE to develop the anti-reflective, anti-fogging and self-cleaning coating that was… research also supported by previous EPSCoR grant when he was a graduate student. They are now broadening… Those for solar panel applications to start with. Now they are broadening their applications to straight lights to improve the energy efficiency of these products. My lab currently has several novel technologies that have commercialization potential. We hope to continue to apply these new technologies to benefit the state of Arkansas and the world at large.
MM: Thank you so much for being with us today, and I look forward to talking to you to some more about your research in the future.
MZ: Okay, thank you.
MM: Music for Short Talks from the Hill was written and performed by local musician Ben Harris. For more information and additional podcasts, visit Arkansas Research. That’s arkansasresearch.uark.edu, the home of science and research news at the University of Arkansas.
