A way to toughen up the latex particles used to make emulsion paints has been developed by UK chemists. The approach involves adding tiny slivers of clay armor to make the particles more hard wearing and fire resistant.
Until now, latex emulsion paints have been made by adding a soap-like surfactant molecule to allow the hydrophobic, or water-hating, polymer ingredients to mix with water. The surfactant stabilizes the paint mixture and allows decorators everywhere the chance to slap on a multitude of colors with a matt or satin finish to walls, ceilings, and other surfaces.
Now, chemist Stefan Bon and Patrick Colver of the University of Warwick have taken a different approach. They have found a simple way to individually coat the prospective paint’s polymer particles with disks of Laponite clay just a few billionths of a meter in diameter. These nanodisks, just 1 nanometer thick and 25 nanometers in diameter, create an armored layer on the individual polymer latex particles in the paint. Because the Laponite clay has an ambivalent chemical nature, it can bond both to the hydrophobic particles but also sit comfortably in the “hydro”, the water. So, not only does it provide particulate protection, it makes the surfactant additive redundant in emulsion paint.
The Lapointe clay disks can be applied using current industrial paint manufacturing equipment and treatment with ultrasound—sonication—say the researchers. Starting materials for the polymers are styrene, lauryl (meth)acrylate, butyl (meth)acrylate, octyl acrylate, and 2-ethyl hexyl acrylate.
The new clay armor is not only about improving home improvements. The team says the same technology can also be used to create highly sensitive materials for sensors. The researchers can take a closely packed sample of the armored polymers and heat it to burn away the polymer cores of the armored particles leaving just a network of nanoscopic interconnected hollow spheres. This gives a very large useful surface area in a very small space which is an ideal material to use in creating compact but highly sensitive sensors.
Bon, S., & Colver, P. (2007). Pickering Miniemulsion Polymerization Using Laponite Clay as a Stabilizer Langmuir, 23 (16), 8316-8322 DOI: 10.1021/la701150q