Nanoparticles in the Coatings Industry
Nanoparticles are small particles that are anywhere from 1-100 nanometers in size. Nanoparticle solutions often have unique properties, making them useful in fields such as food production, medicine, and paints. In the paints and coatings industry, nanoparticles are being used to protect and change the effect of properties in coatings. Due to something called photocatalytic activity, or activation of a chemical reaction by sunlight, nanoparticles of titanium dioxide (TiO2) can react with organic pollutants in the air to neutralize them and wash them away due to the water-loving or hydrophilic nature of the surface. In this sense, these particles have a self-cleaning property, but this tends to degrade with time and UV-exposure.
Nanoparticles of silicon dioxide (SiO2) can be added to paints and coatings to improve the hardness, abrasion, scratch, and weather resistance. They also decrease the elasticity of the paints, which is important for normal stretching and shrinking of the materials with changes in temperature.
There are two main ways to produce nanoparticles; the top-down and bottom-up approach. The top-down approach includes taking a large molecule and breaking it apart to form nanoparticle sized chunks whereas the bottom-up involves building the nanoparticle from scratch and continually adding atoms together until the average size of the particles is within the desired range. Top-down methods are generally faster and are used more on the industrial scale, as this method can produce large amounts of particles at once. However, top-down methods are generally less uniform in size than bottom-up produced particles due to a large amount of mechanical or chemical energy necessary to create them. The most common forms of bottom-up methods involve chemical vapor deposition, physical vapor deposition, and atomic layer deposition.
Each of these involves a gas phase depositing onto a surface to form a thin film of nanoparticles. The volume of particle production of these methods is not as high when compared to top-down methods, but the size of the nanoparticles is much more uniform. Because of this, bottom-up methods are often reserved for special cases where particle size and uniformity are valued more over the amount of material produced.
Nanoparticles have many unique uses already and will likely be in more products in the future. Those who are interested in learning more about nanoparticles, their uses and how they are produced are encouraged to follow these links:
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