Washing whiter and greener: the Science of Laundry

We have all seen the television adverts: people dressed as scientists promoting the latest brand of washing detergent. What is less well known is that synchrotrons are playing a vital role in bringing these and numerous other consumer products to market. “There really is hard science behind our products,” says chemist Eric Robles, who is a research fellow at Procter & Gamble (P&G). “We develop our products based on strong scientific foundation to ensure that they make a significant difference in terms of performance.”

P&G scientists have used the ESRF since 2004, working across several beamlines including ID01, ID02, ID13 and ID19 to study the microstructure of products including hair conditioners, dishwasher liquids, fabric conditioners, shampoos and facial creams. Better knowledge of the microstructure of the colloidal formulations allows researchers to tune the performance and stability of products and meet the company’s strict environmental sustainability targets.

As much as 90% of the energy used to wash clothes goes towards heating the water in washing machines, so one of the main goals is to develop detergents that work at lower temperatures. P&G’s latest innovation, Ariel Excel Gel, boasts cleaning at 15 °C thanks to specially designed enzymes and polymers, offering considerable energy savings. It is also highly concentrated, requiring less water to manufacture and reducing transport and storage costs. 

The majority of liquid detergent formulations, explains Robles, exist as micellar solutions to ensure easy dosing and fast dissolution, but this requires the formula to have a high water content. If the water content is reduced, liquid crystals will start to form unless organic solvent is added, which adds more to the cost of a product and dents its environmental credentials. Another approach is to formulate it as liquid crystal, but the presence of other ions typically destabilises the product and causes “phase splits”. With the help of SAXS, Robles and colleagues mapped the phase diagram of Ariel Excel Gel to determine the regions that are physically stable. As a result, Ariel Excel Gel became the first liquid detergent with a liquid-crystal microstructure with the lowest water content possible without the use of organic solvent, says the team.

It is also vital to test how a product behaves when in use. The performance of washing machines varies widely, so P&G uses a research laboratory instead to assess a product’s washing ability. The team also tests how formulations behave during storage under different conditions, since they have to withstand both the scorching heat of Saudi Arabia and subzero temperatures in Russia. 

“There are only very few capabilities that the ESRF doesn’t have,” says Robles, who is P&G’s global co-ordinator for synchrotron research. “The appeal of the ESRF is its industry office and the relationships that we’ve built with the beamlines over the years.” Synchrotrons in the US are not so well geared up for industry access, he says, and it can be hard to get access to other synchrotron facilities around the world. 

P&G uses other sophisticated techniques including NMR and neutron experiments to improve the stability and environmental credentials of its products. The science behind a product may not always be visible to a consumer, but investing in science is critical to innovation, says Robles. 

Matthew Chalmers

This article appeared in ESRFnews, March 2013. 

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Top image: Synchrotron science is used to develop many household products, ensuring a significant difference in terms of performance. Image credit: Procter & Gamble.