Methyl methacrylate

Methyl methacrylate, or MMA, is a clear liquid with a sharp, fruity smell. Each molecule has five carbon atoms, eight hydrogen atoms and two oxygen atoms. It has a carbon–carbon double bond at one end and an ester group at the other. The double bond is what lets it link up into plastic.

The classic way to make it starts with acetone. Acetone reacts with hydrogen cyanide to make acetone cyanohydrin. Strong sulfuric acid rearranges that into an intermediate, which is then reacted with methanol to give MMA. Newer plants avoid the toxic cyanide. Some start with isobutylene, a four-carbon gas from oil, and oxidize it with air before adding methanol. Others build it from ethylene, carbon monoxide, methanol and formaldehyde. The product is distilled until very pure, and a tiny amount of inhibitor is added so it doesn't link up in storage.

Its main use, by far, is acrylic plastic, used here for the small lenses on the LED strip. It also goes into paints, coatings and adhesives. Surgeons use it too: bone cement is made by mixing liquid MMA with acrylic powder, and it hardens in place inside the body.