Easy-Wash Polymers

It would be great if our dishes could wash themselves, and even better if factory equipment could do the same, because detergents in wastewater cause algae to bloom and otherwise damage the environment. To cut down on the amount of soap that we send down the drain, John Howarter, Kirsten Genson, Jeffrey Youngblood, and colleagues at Purdue University have developed a set of coatings that make it easy to clean oil from metal by simply rinsing with water. The team’s branched copoly­mers have a variety of backbones, but all of them share the same polyethylene glycol side chains, which are capped with fluorinated end groups. Those end groups have a surfactant-like character and drastically increase the interfacial energy between oil and metal while making it easier for water to wet the metal’s surface and displace greasy fluids. Similar materials can be used to prevent glass from fogging up by keeping it free of oily residues that force water to bead up. Youngblood is an avid scuba diver, so he tested some of the substance on his mask. It works better than commercial antifog coatings, he said, but not quite as well as a dollop of spit, which is the classic tool for fixing blurry face wear in the open ocean.