A novel class of two-headed surfactants developed by researchers at St. Francis Xavier University and Dalhousie University has been licensed by a large international distributor, opening the door for the manufacturing of more sustainable dyes, paints and personal care products.
Surfactants serve a critical role in countless industrial processes because of their ability to lower surface tension and allow oil-soluble substances to mix with water-soluble ones. Most have a single polar ‘head’ and non-polar ‘tail,’ but two-headed or ‘gemini’ surfactants have been studied intensely since the term was coined in 1991 by American chemist Frederic Menger. “They have much better properties than you’d predict by just combining two surfactant units,” says Bruce Grindley, a synthetic chemist at Dalhousie University.
Grindley’s team focused on derivatives of pentaerythritol. This inexpensive x-shaped molecule has four hydroxyl groups to which various side chains can be added. Grindley and his co-workers used benzaldehyde as a protecting group, blocking off two of the four hydroxyls and allowing hydrophobic tails to be added to the others. Afterward, the benzaldehyde was removed and replaced with cationic, anionic or even zwitterionic head groups. Gerry Marangoni, a surfactant chemist at St. Francis Xavier University, performed further characterization and testing of the molecules. “In some cases they were up to a hundred times better at lowering surface tension than traditional surfactants,” says Marangoni. This means that lower concentrations can be used, translating into economic and environmental savings.
With the help of commercialization organization GreenCentre Canada, the technology has been licensed to India-based RAN chemicals, which aims to employ them in fullscale processes for the textile, pulp and paper, and personal care industries. “The beautiful thing about these is that you can tailor them to the application at hand,” says Marangoni. “We want to keep this modular theme going, and develop even more, different materials.”