'Solid Smoke' Made From Milk Challenges Plastic Foam

There’s a new polymer contender in the effort to find replacements for expandable polystyrene packaging. David A. Schiraldi, chair of the chemistry department at  Case Western Reserve University in Cleveland, Ohio says that an ultra-light biodegradable foam plastic substitute can be made from the protein in milk and ordinary clay. The new substance could be used in furniture cushions, insulation, packaging, and other products, they report in Biomacromolecules, a monthly journal from the American Chemical Society.

Eighty percent of the protein in cow milk is a substance called casein, which is used in adhesives and paper coatings. But water can wash it away. To increase strength and hike resistance to water, the CWRU scientists blended in a small amount of clay and a reactive molecule called glyceraldehyde, which links casein’s protein molecules together.

The scientists freeze-dried the resulting mixture, removing the water to produce a spongy aerogel. Academics sometimes refer to this family of substances as “solid smoke.” To make the gossamer foam stronger, they cured it in an oven. Almost a third of the material breaks down within 30 days in the right environment, but it’s described as strong enough to have commercial applications.

Schiraldi is chief science officer of Aeroclay, which has been formed to commercialize the technology.  “There is a real intent to commercialize this, and other aerogel products,” says Schiraldi.  Aeroclay is based in Solon, OH.