Nanocomposite Coatings are providing a real opportunity to make a differance across a wide variety or markets. Dr. Juan-Pablo Bravo Vasquez, Chief Scientific Officer of Hy-Power Nano Inc. takes a look at this technology.
Global commercial and manufacturing institutions are excited about the potential of nanomaterial-enabled coatings as they offer the promise of intriguing incremental and disruptive improvements to products and processes. Many of these organizations are actively looking for expertise in the application of nanocomposite technologies to further enhance current commercial products or add completely new properties to existing technology. As a result, a series of new partnership opportunities are beginning to emerge. Global automotive, construction, polymer, solar, glass, oil and gas organizations understand that nanocomposite-based coatings offer significant product performance and cost-saving advantages. These coatings can improve product longevity, surface strength, and product performance, while enhancing energy efficiency performance. Nanoparticles are found in products and applications in a variety of fields, such as ceramics (for membranes), batteries and fuel cells, catalysis and electrolysis reactors, gas storage, electronics, lasers and displays, and magnetic nanoparticles for biological applications such as cancer treatments.
Key properties of nanoparticles
Particle size, surface area and electronic properties are three key properties that make them so desirable for a variety of industrial applications. The large specific surface areas of nanoparticles allow them to have enhanced reactivity, superior absorption, higher solubility, lower melting point and enhanced electronic properties, such as quantum effects found on particles with particle size < 10 nm (important for electronic and optoelectronic applications).
Because of the salient features of nanoparticles, advanced products and coatings can be produced by embedding nanocomposites into polymer matrices. Nanoparticles are invisible to the human eye; when embedded in a polymer matrix. They do not affect visible light transmission, making them ideal materials for advanced clear coats. When nanoparticles are dispersed in polymer to form advanced transparent nanocomposites, they offer improvements in coating strength, thermal and scratch resistance, solar absorption and reflectance (window coatings) and improve performance of photochromic coatings and automotive clear coatings. Polymer nanocomposite coatings embody properties with incredible practical applications for mechanical, optical and electronic products.
No sacrifice in light transmission in optical applications
In general, improving the mechanical properties of a polymer coat (such as scratch resistance) involves the optimization of the polymer lacquer components and reinforcement of the structure of the coat using microscopic fillers. When using nanopowders (size < 100 nm) as fillers to reinforce polymers, their higher interfacial surface area makes the nanofiller behave differently than common fillers; with the nanocomposite requiring very low loading of nanomaterial to yield significant improvement in mechanical and other desired properties.
These properties are enhanced without sacrificing visible light transmission. This is critical for optical applications. In optical applications, nanoparticles and nanomaterials are finding uses in spectrally selective coatings, self-cleaning coatings, super-hydrophobic and super-hydrophilic surfaces, air-cleaning, anti-bacterial coatings, anti-fogging coatings, and water treatments.
Where glass coatings are concerned, spectrally selective coatings made of nanoparticles is a hot topic. Nanoparticles offer greater spectral control than other materials by offering market-leading transparency and clarity. For spectrally selective solar control films, high transparency in the visible light spectrum with absorption and reflection of infrared light are key criteria being considered.
Commercial window films can gain competitive advantage by embedding nanoparticles into plastic films later applied to glass surfaces. Nano films offer heat absorption and reflective properties while maintaining fairly high levels of transparency.
Creating a new era
With the advent of vacuum-based physical vapor deposition technologies, methods such as sputtering and pulse laser deposition have become the primary tools in nanomaterial R&D (although they were originally discovered and produced by solution chemical methods). However, there is a new drive to bring transparent ceramic oxide processing back to chemical solution deposition.
Figure 1 cross-sectional SEM image of a clear coat Nano Composite from Hy-Power Nano’s R&D Facility
Solution-based approaches to nanoparticle-polymer composite deposition are more cost effective than ultra-high vacuum physical processes, allowing a thick layer of nanomaterial to be deposited in a single step. General coating approaches involve dip coating, doctor blade coating, metering rod coating, slot-casting, spray-coating, screen printing and inject printing. All these approaches use nanoparticle-polymer dispersion to cast a nanocomposite polymer onto suitable substrates. A key challenge to this approach is the inherently poor dispersability of specific nanomaterial. Although, there are numerous commercially available nano powders in the market, aggregate contained in those products makes their processing very challenging as they can directly affect performance as well as transparency.
The ability to achieve polymer nano-dispersion amenable to current liquid-based coating processes will usher in an era of nanocoating supremacy over traditional industrial coating products with smarter, stronger, more durable, cost-effective coating materials.
About the author
Dr. Juan-Pablo Bravo Vasquez is Chief Scientific Officer of Hy-Power Nano Inc. (www.hy-powernano.com) of Brampton, ON, Canada. Hy-Power Nano is developing “next generation” nanocomposite coating products that deliver superior performance in a variety of industrial fields. The company has attracted the interest of a number of commercial partners seeking to develop nano-enabled coatings and paints to enhance the energy efficiency of their products and address demanding heat transfer problems. Hy-Power’s nano research facilities are located at Canada’s National Institute of Nanotechnology, as well as top academic facilities across Canada.
