Scientists discover recipe for nearly indestructible plastic

MIT researchers have developed an innovative method to improve the resilience of common polymers (layers) such as polystyrene and rubber. By introducing intentionally weaker bonds, they have made the materials absorb energy more efficiently, opening the door to the extremely resilient products of the future.

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Polystyrene is a hard, glassy plastic that we encounter every day in the form of packaging, cups, plastic utensils and housings for electronic devices. Despite its widespread use, this material has a major drawback. The key drawback is that it tends to crack when hit suddenly. Scientists at MIT have shown that the strength of such polymers and rubber can be doubled by using a special cross-linking molecule.

The researchers actually built intentionally weakened bonds, called mechanophores, into the polymer network. When the material is subjected to an external force, these bonds break in a controlled manner at the point of impact. This action opens up pathways for increased energy absorption and redirects crack propagation, while the stronger bonds that carry the main load remain intact.

To test this property, the scientists used a special system. They fired microscopic silicate spheres with a diameter of about 0.001 cm at a speed of 750 meters per second into thin films of polystyrene. By measuring the speed of the particles before and after the puncture, they calculated the amount of energy retained. It turned out that the material with mechanophores retained significantly more energy than regular polystyrene. Microscopic analyses also showed that the high velocity of the projectile at the point of impact raises the temperature and creates a mobile zone where weak bonds yield to force, while the surrounding area remains stable.

This approach is extremely attractive because it can be applied to existing, commercial plastic and rubber materials with minimal chemical intervention. The team has seen similar success with SBS rubber, which is used in shoe soles and roofing. They are currently investigating the possibility of using it in car tires.

If successful, the process could put an end to sudden tire blowouts on highways, while also drastically reducing the amount of microplastics that are created when tires rub against asphalt and contribute as much as ten percent of all microplastic particles in the environment.