SCIENCE REPORT- Self-Healing Plastic

By Mario Ritter

This is the VOA Special English SCIENCE REPORT.

American scientists have developed the first material that repairs itself. The material is a form of plastic that has been engineered to fill breaks in its surface.

Plastics are used today in everything from airplane wings to hundreds of objects found in the home. Scientists wanted to find a way to make objects made of plastic last longer. The researchers hope their new discovery can be used to make objects that are difficult or impossible to replace.

The surface of plastic objects breaks over time. Very small breaks, or cracks, develop every time a plastic object is used. The researchers wanted to find out how to stop plastic from developing small cracks that grow, weaken and destroy it. The research team at the University of Illinois at Champaign-Urbana found an answer to the problem. They found the answer in the chemical structure of plastic itself.

Plastic is made of small molecules called monomers. These monomers link together to form very long molecules called polymers. Polymers give plastic its ability to be shaped and its strength.

The research team found a way to make plastic that contains very small balloons filled with liquid. The liquid contains monomer molecules the building material of plastic. The team then created solid plastic that contains a special chemical. This chemical is called a catalyst. A catalyst is a substance that starts a chemical reaction.

The new plastic still cracks like common plastic. But, when it does, the monomer liquid is released and flows into the crack. The catalyst in the solid plastic then reacts with the liquid monomer. The chemical reaction between the liquid monomer and the catalyst creates polymer molecules that repair the break. The repaired plastic has seventy-five percent of the strength of undamaged plastic.

The scientists say the new self-repairing plastic is not yet ready for production. But it has several possible uses. One could be in space vehicles where parts cannot be repaired or replaced. Another possible use might be in bridges. And it could be used in people, to replace bone joints that have become broken or damaged. These include knees or hips. The leader of the study is Scott White, a professor of engineering. He says the material is able to repair itself just as the human body is able to heal itself.

This VOA Special English SCIENCE REPORT was written by Mario Ritter.