Instructions on How to Clean Plastics: Add Sunlight

As you prepare for the backyard barbeque, and you have invited over some friends, you pull out the plastic lawn chairs from the shed. Ugh, you think. chairThey sure got moldy over the winter and spring.

Not to worry. They’ll be easy to clean. You’ll just put them in the sun for a few hours.

Voila. Welcome to a world in which plastics fused with titanium dioxide are self-cleaning when they are exposed to the sun.

The developers of the innovation — scientists at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart, Germany — say that UV radiation in sunlight triggers free radicals from titanium dioxide molecules. Those molecules have a tendency to degrade cell walls along with the DNA of fungus and mold, reports The Green Optimistic.

The researchers did a little comparing and contrasting. “We ran some outdoor tests on garden chair armrests with photocatalytic coatings and compared them to ones made from conventional plastic,” says Iris Trick, group manager at the IGB.

They deliberately placed fungi, algae, mosses, and bacteria on plastic chairs with the titanium dioxide. The team found that the plastic was almost completely clean and still white, even after leaving it exposed to the weather for two years, reports International Science Times. Chairs left out for the same period without the titanium dioxide had a layer of dirt that was difficult to remove, the researchers say.

Plastic is not the only surface that can self-clean with the titanium dioxide. “If you apply a thin coating of titanium dioxide to a glass surface such as a smartphone screen, the skin oils and fingerprints gradually disappear from the display by themselves,” says Michael Vergöhl, head of department at the Fraunhofer Institute for Surface Engineering and Thin Films IST in Braunschweig.

One hour of exposure to sunlight does the trick. Previous photocatalytic surfaces on a phone required it to be left in the sun for three days for it to self-clean. The next step, the scientists say, is to develop coatings that can be activated by artificial light.

Manufacturers of cleaning supplies: Be afraid. Be very afraid.

Source: “Solar Powered Coating Developed for Self-Cleaning Surfaces,” The Green Optimistic, 7/18/12
Source: “Chemical Breakthroughs Could Lead to Self-Cleaning Lawn Furniture Activated by the Sun,” International Science Times, 7/18/12