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Green Chemistry

Carbonated-water-based paint acts like high-performance coating

Slightly fizzy product could be a greener option for demanding applications

by Carmen Drahl
April 11, 2018 | A version of this story appeared in Volume 96, Issue 16

Two gloved hands touch two side-by-side strips of white paint. The finger picks up a loose powder coating from the commercial paint, but the new coating is cleaner to the touch.
Credit: Jaddie Ho
The commercial latex paint (right) has poor resistance to mechanical abrasion, but the new coating is relatively clean to the touch.

Replacing solvent-based paints with greener, water-based counterparts sounds nice, but the performance of those alternatives just doesn’t cut it for demanding applications in the furniture or automotive industry. Now, researchers have come up with a waterborne coating that behaves more like a solvent-based paint. In a refreshing twist, the solvent is carbonated water.

Unlike environmentally harmful oil- or solvent-based paints, in which the film-forming polymer that coats a surface starts fully dissolved, water-based latex paints are a suspension of microparticles. “In theory those particles are supposed to merge together to make a continuous film, but they don’t do it very well,” says Philip G. Jessop, who led the work. It’s hard to get a glossy finish with latex paints, and the coatings are damage prone.

Reaction scheme depicts the equilibrium of the CO2-switchable polymer between a water soluble and hydrophobic form.
As carbonated water evaporates, the water-soluble polymer converts to a durable coating.

To make their new paint, Jessop, graduate student Jaddie Ho, and their colleagues at Queen’s University started with a carbon dioxide-responsive polymer (Green Chem. 2018, DOI: 10.1039/c8gc00130h). Its charged side chains allow it to dissolve in carbonated water, but once applied to a surface, the water and CO2 evaporate and the polymer becomes neutral, creating a glossy, hydrophobic coating. The team added cross-links between polymer chains to further improve durability, and that coating had better resistance to water and abrasion than a commercial latex paint purchased at Home Depot.

Two side-by-side strips of white paint show the difference in water resistance between a commercial latex paint and the new coating.
Credit: Jaddie Ho
After one week immersed in water, the commercial latex paint (top) develops bubbles, but the new coating stays smooth.

Because of its increased toughness, this paint might be suitable for a broader range of applications compared with traditional latex paints, including appliances and office furniture, says Phillip G. Phillips, president of coatings consulting group Chemark. Coatings expert Mohamed S. El-Aasser of Lehigh University praised the novelty of the carbonated solvent. While he notes there’s a long way to go between a proof-of-concept study and industrial-scale production, he’s optimistic the team can address formulation and other challenges.

The researchers have applied for a patent on the coatings and are collaborating with color technology firm Lorama Group. Jessop notes that because the paint’s CO2 pressure is equal to atmospheric pressure, any future containers of the product sadly won’t make that satisfying soda-can hiss when opened.


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