Topic: Self repairing plastic

[Nemesis]

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The secret lies in the small molecular links or "bridges" that span the long chains of chemicals that compose plastic. When plastic is scratched or cracked, these links break and change shape. Prof Urban tweaked them so that changes in shape produce a visible colour change — a red splotch that forms around the defect. In the presence of ordinary sunlight or visible light from a light bulb, or acidity and temperature changes, the bridges reform, healing the damage and erasing the red mark.