Janus particles are engineered to have two surfaces, each with distinct physical properties. One combination for a Janus particle is to have one side hydrophilic (attracted to water) and the other hydrophobic (water-repellant). Until recently, Janus particles could not be produced in large quantities and their commercial applications were unclear. Researchers have now shown that the nanoparticles could be the key to more environmentally friendly paints and coatings.
Previous studies are focused on structures formed by these particles at a very small scale because they have unique surface properties. The new work uses these particles to improve the performance of paints and coatings. When painting a wall, for example, to do it properly, there are a few general methods: apply a primer layer and then a paint layer, which can take twice the time; mix paints with solvents but solvents are a health risk and fumes can be an issue in poorly ventilated spaces; or use water-based paints, such as latex or acrylic latex, but many of those still contain solvents and may not be as durable.
The research team mixed hydrophilic/hydrophobic Janus particles with commercial paints, then painted surfaces to see how the particles would react. The hydrophilic side oriented to the surface and helped the coatings adhere better, while the hydrophobic side faced toward the surface and made it water-repellant. The particles diffused and arranged themselves into self-stratifying layers more quickly and in ways that did not completely follow the team’s hypotheses.