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Replacing titanium dioxide as opacifier: consider a shape change

Replacing titanium dioxide as opacifier: consider a shape change

A fresh lick of paint breathes new life into a tired looking place. Ever wondered how a thin layer of paint is so effective in hiding what lies underneath from vision? Beside colour pigments, and a binder that makes it stick, paints contain microscopic particles that are great at scattering light and turning that thin layer of paint opaque. The golden standard for these opacifiers are small titanium dioxide particles, of dimensions considerably smaller than one micron. Their use is not without controversy, as they are a big environmental burden, with a large carbon footprint and a questionable impact on human health. The reason why titanium dioxide particles are great at scattering light is that they have a high refractive index compared to the other paint ingredients, so when distributed throughout the dried paint film their hiding power of the underlying surface is fantastic. When no coloured pigments are used, the coated surface appears then whiter than white.

Ideally though, titanium dioxide should be replaced, but the list of safe high refractive materials is very limited. This makes you wonder if there is another handle, beside refractive index? Can we design efficient scattering enhancers from materials of lower refractive index?. Inspiration came from the white Cyphochilus beetle, native to southeast Asia. The scales of the beetle are not made of high refractive index materials, but they thank their white appearance to an intricate anisotropic porous microstructure, resembling the bare branches of a dense bush.

BonLab fabricates textured microcapsules through crystallization

BonLab fabricates textured microcapsules through crystallization

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Microcapsules can be found in a range of commercial applications, including cosmetics, healthcare, agriculture, and food. The capsules serve as a storage vessel for an active ingredient, for example a nutrient or fragrance. They can have a variety of designs, the simplest form being a single internal liquid-based core surrounded by a solid shell. The chemical and physical characteristics of this shell influence the colloidal stability of capsules in formulations, dictate the permeability and mechanical robustness of the capsules, and can potentially regulate substrate adhesion. Beside storage, these features of the microcapsules are there to regulate and control release and delivery of the active compound.

A considerable part of the technologies used to produce microcapsule relies on the use of synthetic polymers that do not break down, with terrible consequences for environmental build up. One way is to make use of biocompatible and degradable plastics.

We provide an alternative solution, in that we fabricate the capsule from small molecular compounds, instead of polymers, that can crystallize.

What happens to particle size distributions when making reactive surfactants and polymer colloids by emulsion polymerization?

What happens to particle size distributions when making reactive surfactants and polymer colloids by emulsion polymerization?

When we synthesize polymer colloids by emulsion polymerization, molecular surfactants are often employed. These are required to keep the polymer latex particles dispersed in the water phase, so that they do not clump together, a phenomenon known as coagulation. Keeping polymer dispersions stable is especially important in end applications, such as waterborne coatings and adhesives.

A downside of the use of surfactant molecules is that they can desorb from the surface of the latex particles. This makes the particles colloidally unstable, and they coagulate. This can be disastrous in product formulations, such as water-based paints which have many components. Another downside of this mobility of the surfactant molecules is that they can migrate in the final coating, once applied on a substrate. This leads to deterioration of the properties of the coated film.