A new material design could reduce pollution where the rubber meets the road. Strategically adding weak points to microscopic chains called polymers actually makes the chains harder to tear, scientists report in the June 23 Science. Because polymers are used in car tires, the findings could help reduce plastic pollution as tires wear down over time.

As tires scrape against the road, they drop tiny particles of rubber and plastic polymers that can pollute waterways and contaminate the air. Globally, tires shed about 6 million metric tons of this debris into the environment each year. Stronger polymers that break apart less easily could limit the pollution.

Chemist Stephen Craig of Duke University and colleagues made their tough material by adding easily breakable molecules called cross-linkers to the polymers. The polymers act like a tangle of spaghetti noodles with the cross-linkers holding them all together, helping them retain their shape. Individual cross-linkers broke easily when the team stretched the polymer strands, but ripping the bulk material required more force than expected. The secret to the increased toughness lies in the path the tear takes. The tear propagates through the cross-linkers, following the path of least resistance. But making it through the long polymer strands means breaking many cross-linkers, which requires more force overall. Craig hopes the findings will help extend the lifetimes of car tires.

– Skyler Ware

Watch a video of tear-resistant rubber in action at bit.ly/SN_ToughTires