Algae bloom in canal

Algae-choked waterways are often treated with acrolein, which is produced by degradation of a newly concocted molecule. Credit: Pedro Portal/Miami Herald/TNS/Getty

Chemistry

This polymer carries the seeds of its own destruction

A molecule’s partial dissolution generates acid, leading to runaway degradation.

A new type of self-destructing polymer could be formed into soluble capsules for drug delivery or temporary scaffolds for 3D printing.

Polymers consist of repeated chemical subunits held together by chemical bonds. Various methods can be used to break these bonds, but many such methods are slow or require relatively large amounts of a ‘triggering agent’ to start the degradation.

Steven Zimmerman and his colleagues at the University of Illinois at Urbana-Champaign cooked up polymers that start to fall apart when placed in a slightly acidic environment. As a polymer molecule dissolves, it produces acid, which in turn breaks apart more of the remaining molecule, until it is no more. As a result, a molecule’s decay rate becomes exponentially faster as its degradation progresses. Large amounts of a chemical trigger are unnecessary, because a molecule’s disintegration ultimately fuels itself.

Similar polymers could be used to make consumer products that degrade quickly. One polymer variety that the team developed releases acrolein, which is used to fight the algae and bacteria that foul irrigation canals.