Self-Healing Thermoplastic ‘Bleeds’ to Indicate Damage

Plastics play an increasingly larger role in many designs and structures, but have an inherent limitation: when plastics are damaged, they generally have to be replaced. So what could you do with self-healing plastics that can also visibly indicate when they’ve been compromised?

A team of researchers have come up with what they call a new category of plastics that mimic human skin in their ability to self-heal scratches and cuts — and even “bleed.” The plastics change color to indicate wounds, and can heal themselves when exposed to light.

Professor Marek Urban of the University of Southern Mississippi in Hattiesburg reported on the research at the 243rd National Meeting & Exposition of the American Chemical Society in late March.

Urban’s team (with some funding from the Department of Defense) developed water-based thermoplastics that include small molecular links that span chains of chemicals in the plastic. If the plastic is scratched or cracked, the links break and change shape. The group further refined the links so that they produce a visible color change: a red mark near the damage. The links can then be reformed with exposure to ordinary light, pH changes, or heat.

“Mother Nature has endowed all kinds of biological systems with the ability to repair themselves. Some we can see, like the skin healing and new bark forming in cuts on a tree trunk. Some are invisible, but help keep us alive and healthy, like the self-repair system that DNA uses to fix genetic damage to genes. Our new plastic tries to mimic nature, issuing a red signal when damaged and then renewing itself when exposed to visible light, temperature or pH changes.” — Marek Urban, University of Southern Mississippi.

Such plastics could be used in auto fenders (which could be repaired via exposure to intense light) or even in structural aircraft parts, where the color changes could alert engineers to potential damage.

Urban says that the new plastic have another advantage over other self-healing plastics alternatives: the plastic can reform multiple times.

You can a news report below, or watch a time-lapse video here:

Source: American Chemical Society

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