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Queen’s University researchers invent new class of paints that could revolutionize water-based paints.

When it comes to paint, there are two main types people can chose from, latex or oil-based. But now, a new option has been developed at Queen’s University that promises a more environmentally-friendly choice.

[Paint Strips]
The new paint (lower test strip) is more resistant to water than a commercial latex paint (upper strip). This shows what happens when both paints are painted onto a piece of unprimed aluminum metal, allowed to dry, and then exposed to water for a week.

Philip Jessop, the Canada Research Chair in Green Chemistry, Michael Cunningham (Chemical Engineering), and graduate student Jaddie Ho have developed a water-based paint that behaves more like a solvent-based paint (also known as oil-based paint) – except the solvent in this case is not an organic solvent, but carbonated water.

Due to its increased toughness and very low environmental impact, this paint might be suitable for a broader range of applications compared with traditional latex paints, including appliances and office furniture.

“Most consumers already use water-based paints, because high performance isn’t needed when you paint your living room,” Dr. Jessop explains. “However, industry still uses oil-based paints when they paint something they just manufactured, because they need the paint to be hard, glossy, scratch-resistant, and incredibly smooth. By giving industry a water-based paint that works the same way as an oil-based paint, we hope to reduce organic solvent emissions from industrial operations and thereby reduce harm to the environment and health risks to workers.”

Why do oil-based paints work so well? Dr. Jessop explains all paints consist of a liquid, a polymer and additives like pigments. In oil-based paints, the liquid is an organic solvent and the polymer is dissolved in it, which ensures the polymer is effective but when you spray or brush an oil-based paint onto a surface, the solvent evaporates, causing environmental harm, and the polymer is left behind as a smooth film on the wall.

[Paint on fire]
Normal oil-based paints are flammable and smog-forming, left, but the new paints, right, work the same way as oil-based paints without using any organic solvent. This shows what happens if the wet paint is brought near to a candle. The oil-based paint catches fire but Dr Jessop's paint doesn’t.

In water-based paints, the liquid is water and the polymer isn’t dissolved, it’s tiny balls of plastic suspended in the water. When you apply a water-based paint to a surface, those little balls are supposed to merge with each other to make a layer of plastic on your wall, but that often doesn’t work very well.

The new formula which uses carbonated water (club soda) will dissolve some basic polymers and makes water-based paint behave like oil-based paint. Regular water cannot achieve this.

“If you use our paint,” says Dr. Jessop, “you’ll brush or spray our mixture of carbonated water and dissolved polymer onto a surface and the club soda will evaporate, leaving behind a smooth, water-repelling polymer film in just the same way as an oil-based paint but without the same risk to your health or the environment.”

The new paint is also more resistant to water than a commercial latex paint, is non-flammable and also works well at lower temperatures, such as outside in the fall or spring.

Dr. Jessop and his research team are currently working with GreenCentre Canada and a paint and coating company to refine the technology.

“Paints and coatings are complicated mixtures of polymer, liquid, pigment, preservatives, opacity agents, and other components. Finding the best recipe using these ingredients is a complex and time-consuming task but necessary before a technology like this can be sold,” he says.

The paper was published in Green Chemistry.