Nanotechnology Advances for Functional Coatings – R&D Overview

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

A team ofGerman 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

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

#3. Nanoparticles-based Transparent Coating to Prevent Fogging

Researchers 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

#1. Converting Wasted Energy into Useful Electricity

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.

#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.

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.

#3. Ceramic Coating That Controls Heat Radiation

Not 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.

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 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.

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.