Slippery business: Materials scientists invent new coating for self-cleaning, water-efficient toilets Slippery business: Materials scientists invent new coating for self-cleaning, water-efficient toilets - ImagesGram

Slippery business: Materials scientists invent new coating for self-cleaning, water-efficient toilets

A nice clean toilet. Image: Usein.
Monday, November 18, 2019: It's a dirty field, but someone's got to study it. In findings reported today in Nature Sustainability, researchers from Pennsylvania State University in the U.S. report the invention of a new coating that could reduce bacterial growth, water waste, and unpleasant odors when sprayed onto a bog-standard house toilet.

"Our team has developed a robust bio-inspired, liquid, sludge-, and bacteria-repellent coating that can essentially make a toilet self-cleaning," study co author Tak-Sing Wong, said in a press release. Wong is Penn State's Wormley Early Career Professor of Engineering and an associate professor of mechanical engineering and biomedical engineering.

The invention, called a liquid-entrenched smooth surface (LESS) coating, involves two separate treatments, both reportedly suitable for spraying onto ceramics. The first spray is made of molecularly grafted polymers, specifically polydimethylsiloxane silicone, that co-developer Dr. Jing Wang described as resembling human hairs once it has dried on the target surface, which makes it very smooth. The second spray covers the target surface in silicone lubricant. According to the report, the two sprays take less than five minutes to dry and would last for roughly 500 flushes before requiring reapplication.

Carl Hensman of the Bill and Melinda Gates Foundation, which offered contest for redesigning the toilet some years ago, noted that the ingredients int he sprays are also found in common toiletries like toothpaste and are unlikely to pollute nearby water supplies, though he also remarked that, because the spray wears off, it was unlikely to be used in developing countries.

"When we put that coating on a toilet in the lab and dump synthetic fecal matter on it, it (the synthetic fecal matter) just completely slides down and nothing sticks to it," said Wang.

A Penn State press release suggests that widespread use of this treatment on toilets could reduce the amount of water used to flush toilets, currently 141 billion liters daily, by half and would also improve the performance of waterless toilets and urinals.

Wong and his partners have started a company, spotLESS Materials, to transform their invention into a product. "As a researcher in an academic setting, my goal is to invent things that everyone can benefit from," said Wong. "As a Penn Stater, I see this culture being amplified through entrepreneurship, and I'm excited to contribute." They have already received support from the Rice Business Plan Competition, Ben Franklin Technology Partners' TechCelerator, Y-Combinator, and the United States' National Science Foundation, Department of Energy, and Office of Naval Research.