Sarah Eckersley tells the story behind how Dow solved a decades-long problem, making house paints greener and more efficient
By: Leigh Krietsch Boerner, special to C&EN
It was an old problem. Even 30 years ago, scientists knew they needed to stop relying so much on titanium dioxide in paints, says Sarah Eckersley, global R&D director for coatings, monomers, and plastics additives at Dow Chemical. TiO2 is important in paints because it scatters light and covers the colors underneath, but extracting and processing it slurps up energy and water and belches out toxic waste. It’s also the single most expensive part of paint, Eckersley says.
But reducing the amount of TiO2 in paint was not easy. Dow’s effort, which won a 2017 Heroes of Chemistry Award from the American Chemical Society, took a village. The core team consisted of more than 20 Dow scientists, but many more people contributed, she says. They really started working hard on this problem about 10 years ago. And in the early days of the project, the team would update the entire Springhouse, Pennsylvania, site on its progress because everybody felt so invested in seeing it succeed, she says. “People who actually sat in other business R&D groups would come to hear about the progress, but also to contribute ideas,” she says. What resulted were two technologies for paint: Avanse acrylic resins and Evoque precomposite polymers.
Midland is where Eckersley calls home. Originally from England and Canada, she’s lived in the US for about 25 years, all of them working for Dow. “I've had a theme throughout my career of being associated with coatings and colloids going all the way back to my PhD,” she says. It is unusual at Dow to have done PhD work so closely aligned to the technology in a business you lead.
But it was this background that helped Eckersley with the Avanse and Evoque projects. The challenge in resolving the TiO2 problem was twofold: paints rely on TiO2 to bounce light away so that when you apply paint to a surface, you can’t see the color underneath; and reducing the reliance on TiO2 in paint meant that the scientists had to decrease the amount of the compound they put in, while maintaining the same coverage level. In the old technologies, TiO2 and other ingredients are distributed in a continuous water phase, Eckersley says. “When the paint dries, the water evaporates, and you would end up with a very random, disordered structure.” This means that the TiO2 would leave splotches of color underneath showing through. Scientists would compensate by adding more TiO2 to the paint, which would make the paint more expensive and have higher environmental consequences because of the way the compound is manufactured.
Eckersley's team ultimately solved the problem by suspending the TiO2 in a polymeric framework, which maintains order as the paint dries. “You basically go from randomness to order, and you keep those titanium dioxide particles separated from one another,” Eckersley says. The result: paint with 20% less TiO2 and better coverage in a single coat.
This result did not come easily. Early versions worked almost too well, Eckersley says. “We would go from a flowing can of paint to essentially a solid mass,” she says. The aha moment was when the team realized how to achieve a balance between ensuring that the paint could support the necessary polymeric network and preventing the paint from solidifying during the manufacturing process, Eckersley says.
But “you don't actually have a positive environmental impact until the technology is practiced in a widespread way,” Eckersley adds. It’s great to have a cool idea, but big ideas that aren't actually succeeding in the marketplace aren't truly contributing to sustainability. What’s so exciting about this technology, she says, is that it’s actually being used, in a big way. “It's been in every paint market on a global basis. And the benefits are really tangible.”