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Chemistry

The Chemistry of Photochromic Molecules: From Sunglasses to Smart Windows

Quick fact

Some photochromic molecules can switch between two forms—one clear, one colored—over a million times without degrading, making them durable enough for everyday eyewear.

Why this is interesting

Ever wondered how your sunglasses darken on a sunny day and clear up when you step indoors? That magic trick is chemistry in action.