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Nanotechnology Advances for Functional Coatings – R&D Overview

Payal Ahuja – Feb 20, 2020

TAGS:  Smart Coatings 

Nanotechnology Advances for Functional CoatingsThe application of nanomaterials continues to attract attention embracing the new generation of coating technologies. Nanotechnology-enabled smart coatings could prevent your electronics from scratching, can make cloths or smartphones waterproof (remember P2i’s water-proof nanocoating!) or even perform other minor modern miracles.

The list of benefits offered by nanocoatings in applications is huge! Thus, growing application interest is not only driving advance research efforts to develop new nanocoatings, but the industry is also increasingly incorporating nanotech-enhanced smart coatings in real-world applications!


Going beyond graphene…

As we all know, “graphene” has already earned the interest in several industries with a host of attractive features & properties. It has been at the forefront of nanomaterials research over the past few years. But today, researchers are also exploring other materials (e.g. 2D layered materials) contributing to the popularity of highly functional, nano-enabled coatings.

Thus, going beyond graphene in this special coverage on nanocoatings advances, we bring you some very interesting developments from the nanocoatings R&D world. Also, explore real world examples of nano-enabled coatings proven beneficial across many applications.

Let’s begin with tackling unpleasant greasy smudges or fingerprints on everyday products…



Preventing Fingerprints, Smudges and Fogging


#1. Nanocoating to Prevent Greasy Smudges on Stainless Steel Surfaces


Greasy FingerprintsA team of German researchers has created a new nanocoating that uses its water and oil repellant properties to:

  • Prevent fingerprints on stainless steel surfaces and
  • Protect metal surface from harmful effects of greasy film

The layer of coating containing special additives works in two different ways:

  1. The small surface area of contact
    “When the particles integrated into the coating settle on the surface of the stainless steel, the surface becomes rougher and its surface area increases. When a finger comes into contact with the refrigerator door, it only touches the raised points on the surface and the grease on the fingertip never reaches the “valleys” of the stainless-steel surface. This means the surface area which actually comes into contact with the grease is kept very small.”

  2. Adjustment in the refractive index of the coating
    “The refractive index of the coating has been adjusted so that it matches that of the skin’s natural oil content. This means light is reflected by the coated stainless-steel surface in about the same manner as by a surface that has been touched by sticky fingers. As a result, the fingerprints are hardly noticeable.”

Nanotechnology specialists at FEW Chemicals GmbH are handling the development of the coating systems, while the Fraunhofer team is concentrating on the analysis of these layers to prevent smearing. Furthermore, the researchers are developing an automatic testing machine for the layers. The device is not intended to investigate the particles in the coating, but rather the visibility of the fingerprints themselves.


#2. NANOPRINT Anti-Fingerprint Formula to Improve Glass-based Surfaces in Variety of Industries


fingerprint-free-coating MetaShield offers an anti-fingerprint nanotechnology-based coating called “NANOPRINT”. It is an optically transparent coating designed for glass-based surfaces.

Key benefits include:

  • Creates a single, thin layer adhering to glass surfaces to absorb/repel dirt, water, oils, sweat
  • Reduces the appearance of fingerprints and smudges by as much as 70%
  • Improves the performance and appearance of touch-based technology
  • Increases product’s cleanability while decreasing maintenance time and costs

Main applications:

Consumer products Commercial applications
  • Automotive interiors
  • Electronic devices with touch-based
    technology household appliances
  • Mirrors
  • Buildings
  • Public touch-based screens
  • Display cases
  • Storefront and residential windows
  • Architectural glass
  • Camera-based sensors


#3. Nanoparticles-based Transparent Coating to Prevent Fogging


Antifog CoatingResearchers at ETH Zurich have developed a durable coating made of gold nanoparticles embedded in non-conductive titanium oxide which prevents fogging on transparent surfaces. According to the team, the coating relies on sunlight to heat the surface. It absorbs the infrared component of sunlight along with a small part of the visible sunlight and converts the light into heat.

Tests have shown that when exposed to sunlight, fogged surfaces coated with gold nanoparticles and titanium oxide clear four times faster than surfaces treated with a normal anti-fog agent.

Possible applications: Ski goggles, diving masks, eyewear, camera lens, car windows


Nano-enabled Coatings and Energy Harvesting/Saving Solutions


#1. Converting Wasted Energy into Useful Electricity


Energy-harvesting nanomaterials created KAUST has developed a thermoelectric nanomaterial that could capture the heat lost by devices, ranging from mobile phones to vehicle engines, and turn it directly back into useful electricity.

The nanomaterial is made by spin coating a liquid solution of nanomaterials called quantum dots. The team spin-coated a thin layer of lead-sulfide quantum dots on a surface and then added a solution of short linker ligands that crosslink the quantum dots together to enhance the material’s electronic properties.

This low-temperature solution-based production process makes it suitable
for coating on flexible plastics for use almost anywhere.
 


#2. Boron Nitride-based Nano-coating for Longer-lasting Lithium Batteries


In 1980, John Goodenough invented the modern lithium-ion battery and today, they have become an extremely important energy source for humans. However, it is hard to improve energy storage and increase battery life while ensuring safe operation.

Now, Columbia Engineering researchers have developed a new method for safely prolonging battery life.
Li-Batteries
Boron Nitride-based Technique for Longer-lasting Lithium Batteries

Previous research has shown that energy density could be improved by using lithium metal to replace the graphite anode, but this method can cause short-circuiting and essentially lower battery safety.

However, in the study, they focused on solid, ceramic electrolytes. They inserted a nano-coating of boron nitride (BN) to stabilize solid electrolytes in lithium metal batteries. They deposited 5~10 nm boron nitride (BN) nano-film as a protective layer to isolate the electrical contact between lithium metal and the ionic conductor (the solid electrolyte), along with a trace quantity of polymer or liquid electrolyte to infiltrate the electrode/electrolyte interface.

The materials show great promise in improving both safety and energy density, as compared with conventional,
flammable electrolytes in Li-ion batteries. 


#3. Ceramic Coating That Controls Heat Radiation


ceramic-carbon-nanotubesNot only limited to enhancing the lifespan of batteries, but Boron Nitride can also be a wonder material to increase the lifetime of the coating and thus, increasing efficiency of components inside jet engines and electricity-generating turbines.

Ceramic coatings are standard inside the hottest part of turbines. They protect the turbine blades from high temperatures, protect the nickel alloy that forms the blade structure and thus allow operation above the melting point of the metal. But although these coatings play a vital role in the structural stability of the blade, they do not actually control how the blade radiates heat, which compromises the performance and efficiency of the turbine.

Now, researchers from Purdue University have developed a coating comprised of ceramic (boron nitride) nanotubes which act as thermal antennae, controlling both the direction and the electromagnetic spectrum of heat radiation.

These boron nitride nanotubes control radiation through oscillations of light and matter, called polaritons, inside the ceramic material. High temperatures excite the polaritons, which the nanotubes – as antennas – then couple efficiently to outgoing heat radiation.

According to the study, the antennas could bring the ability to accelerate the radiation,
perform enhanced cooling of a system or send information in very specific directions or wavelengths.
 


Blackest Black Carbon Nanotube Coating


Last year, BMW has unveiled ‘the world’s blackest’ car using nanotech coating called “Vantablack”. Hussein Al Attar, the designer responsible for the new BMW X6, calls his work “The Beast”.

Vantablack: The World's Blackest Car
Vantablack: The World's Blackest Car

Vantablack is a coating of carbon nanotubes, and not actually a color pigment or a paint. It absorbs incident light almost completely. Against a deep black background, objects coated in Vantablack material seem to disappear, as the perception of spatial depth is lost. This is because the human eye perceives shapes coated in Vantablack to be two-dimensional.

During the same time when “The Beast” was launched, MIT engineers claimed to have created a blackest black coating from carbon nanotubes that is reportedly 10 times darker than any material created before, including Vantablack.
CNT BASED COATINGS
New CNT-based Coating is 10 Times Blacker

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.

According to the study, 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.


More ‘Not to Miss’ Nanocoating Innovations!


Innovation Description
Temperature Regulating Fabric

Temperature Regulating Fabric


  • Fabric automatically regulates the amount of heat that passes through it.
  • Made from specially engineered synthetic yarn coated with a carbon nanotube coating.
  • In warm and humid conditions, when the body is sweating on a hot day, the yarn contracts, allowing more infrared radiation coming off the body to pass through. When it's cool and dry, the yarn expands, trapping that same heat.

Possible Applications: Sportswear, Clothing, bed linen
Source: University of Maryland
Nano-silver Coating for Dental Implants

Nano-silver Coating for Dental Implants


  • Depositing a nano-scale thin film of silver on the titanium surface to reduce implant failures due to infection.
  • ‘Nano-silver’ coat ensure controlled release of silver up to 22 days, maintaining a long-term antibacterial activity.

Possible Applications: Dental Implants
Source: Agharkar Research Institute (ARI), Pune
MetaShieldCLEAN

MetaShieldCLEAN - Stains, Dust and Dirt Repellent Nano coating


  • Fully transparent, nanotechnology-based coating a low volatile organic compounds (VOC) high solids content.
  • Scratch and scuff resistant.
  • Anti-dirt and anti-stain function.
  • Enhances the durability, lifespan, and appearance of polymers.

Possible Applications: Consumer products, Packaging products, Ideal for the cosmetics industry
Source: MetaShield LLC
Magnetoelectric and Magnetocaloric Smart Composite Material

Magnetoelectric and Magnetocaloric Smart Composite Material


  • A composite material constructed from magnetic nanoparticles incorporated into a PVDF matrix.
  • Piezopolymer matrix that can change its temperature and parameters under the influence of magnetic and electrical fields.
  • May be used as a basis for implant coating.

Possible Applications: Biological Implants
Source: Baltic Federal University
SWCNTs

Flexible Conductive Coating for ‘Smart’ Nonwovens


  • Conformal conductive coating uses a formulation of dispersed single-walled carbon nanotubes (SWCNT).
  • Coating does not add unwanted weight or bulk or change the flexibility or drape of the fabric.
  • The resulting coated nonwoven fabric combines tear and tensile strength from base fabric and functionality from coating, thus producing intelligent fabrics with many different possible combinations of desirable performance characteristics.

Possible Applications: Nonwoven materials used in medical, automotive, energy, etc.
Source: Battelle


Explore Smart Functional Coatings Innovations


Map new development opportunities for your functional coatings in today’s market by reviewing trends of Smart Coatings Event 2020, USA! Take the Course on "Smart Functional Coatings: Update on Current & Future Opportunities" by Mike Clingerman.

smart coatings innovations



References

  1. https://www.fraunhofer.de/en/press/research-news/2019/july/nanocoating-prevents-greasy-smears.html
  2. https://mma.prnewswire.com/media/1024564/Nanoprint_fingerprint.jpg?p=twitter
  3. https://ethz.ch/en/news-and-events/eth-news/news/2019/03/nanotechnology-and-sunlight-clear-the-way-for-better-visibility.html
  4. https://discovery.kaust.edu.sa/en/article/838/energy-harvesting-nanomaterials-created-cool
  5. https://engineering.columbia.edu/press-release/yuan-yang-longer-lithium-battery
  6. https://www.purdue.edu/newsroom/releases/2019/Q4/new-antenna-tech-to-equip-ceramic-coatings-with-heat-radiation-control.html
  7. https://www.bmw.com/en/design/the-bmw-X6-vantablack-car.html
  8. http://news.mit.edu/2019/blackest-black-material-cnt-0913
  9. https://indusdictum.com/2020/02/14/agharkar-instt-pune-develops-materials-that-can-reduce-dental-implant-failure/
  10. https://www.eurekalert.org/pub_releases/2020-01/ikbf-sma012020.php
  11. https://www.nonwovens-industry.com/issues/2019-03-1/view_features/smart-heating-a-flexible-conductive-coating-for-nonwovens

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