Most synthetic polymers - Greek for many parts," because they are long chains of many identical molecules - were not designed to disintegrate. They were meant to last as long as possible. But synthetic polymers became so popular [that] they're at the root of the global burden of billions of tons of plastic waste. The environmental effects of plastic buildup and the declining popularity of plastics have helped to spur chemists on a quest to make new materials with two conflicting requirements: They must be durable, but degradable on command. In short, scientists are in search of polymers or plastics with a built-in self-destruct mechanism. The starting point requires picking polymers that are inherently unstable. Dismantling these polymers is sometimes called unzipping them, because once the polymers encounter a trigger ... their units fall off one after another until the polymers have completely switched back to small molecules. "We can have a big change in properties or complete degradation of the polymer just from one event," says Elizabeth Gillies, a polymer chemist. On-demand, rapid disintegration gives unzipping polymers an edge ... she says, as biodegradation is often slow and difficult to control. These next-generation polymers could help mitigate pollution problems associated with plastic products. If the units were collected after unzipping to make new polymers, that would lead to chemical recycling. Most recycling done today simply involves melting the plastic and remolding it.