Nanoparticles may be the secret ingredient in making ultimate plastics

A sprinkling of nanoparticles could be the solution to a problem that has long plagued plastics manufacturers – namely, how do you make a material that is both strong, tough and easy to work with?

Hu-Jun Qian at Jilin University in China and his colleagues call this the plastics trilemma: making a polymer stronger, or harder to deform, tends to make it more brittle, or less tough, while attempting to improve both of these properties at once normally makes the material more viscous and harder to work with.

To get around this, the researchers mixed nanoparticles made from polystyrene with several commonly used plastic materials. For example, they added the nanoparticles to PEMA, a polymer that is used to make hearing aids and artificial nails, acrylic glass used in aquariums and eyeglasses, and PVC, which is used in construction and packaging.

The team put the resulting materials through a series of tests to see, for example, how much they could elongate before breaking. In general, the new materials showed better-than-usual performance across different tests, sometimes dramatically – they found that PEMA was about 50 per cent stronger when fortified with nanoparticles. “This offers a general design principle for next-generation polymers with previously unattainable combinations of properties,” says Qian.

To better understand why adding nanoparticles was so helpful, the researchers also carried out computer simulations of the new materials. For the case of plastics under stress, these simulations showed that nanoparticles can move and redistribute within the material, thus allowing it to deform more slowly and smoothly instead of failing. Their ability to move was similarly beneficial for plastics flowing more easily when melted. So they were stronger, tougher and workable.

Qian says that his team’s approach is compatible with existing industrial processes and could be scaled up to large quantities. “This strategy could revolutionise applications requiring lightweight, strong, tough and easily processable materials—such as automotive and aerospace composites, sustainable packaging, biomedical devices and advanced recyclable plastics,” he says.