We've already heard about new types of packaging that use things such as sorbic acid and silver nanoparticles to keep food fresh for longer, but this week scientists from Texas A&M; University announced the development of a "nano-brick" film that utilizes yet another substance to achieve the same purpose. That substance is montmorillonite clay, which is one of the ingredients used to make bricks. The film is about 70 percent clay (with the rest of it made from various polymer materials) and when its structure is viewed through an electron microscope, it actually even looks like bricks and mortar.
The transparent film would be applied to existing packaging, through a spraying or dipping process, and is less than 100 nanometers thick – much thinner than a human hair. Thin though it might be, it is said to add considerable strength to the host material, and to act as an improved barrier for keeping oxygen from reaching the food. In lab tests, it was reportedly shown to be 100 times more oxygen-impermeable than existing silicon oxide coatings.
Food wrap incorporating silicon oxide has itself recently been praised for its gas impermeability, as have plastic films with a thin metal or foil coating. According to A&M;'s Dr. Jaime Grunlan, however, the foil wraps let in about as much oxygen as as the silicon oxide, aren't transparent, and can't be put in a microwave oven. Even clay/polymer films have been created before, but Grunlan states that they weren't remotely as impermeable as his team's film, thanks to its brick wall-like structure.
He is now working on making the film more moisture-resistant. Farther down the road, he would also like to make it sunlight-impervious and antimicrobial. Besides its use in food packaging, it could also conceivably find its way into flexible electronics, scratch-resistant surfaces, tires, and sporting goods.
The research was presented at the 241st National Meeting and Exposition of the American Chemical Society.