Materials: Brute force yields new molecules

Urbana (USA), 28 March: Chemists have designed a new type of molecule that changes identity when a mechanical force is applied. Apart from offering new ways to control chemistry, the effect might even result in mechanically responsive polymers that warn of impending structural failures, delay damage or even self-repair.

In most chemical reactions, reactants need to overcome an energy barrier before they are turned into products and the energy needed for this is usually provided by heat, light, pressure or electrical potential. In this week’s Nature, Jeffrey S. Moore and colleagues use mechanical force to achieve the same effect.

The team added carefully designed, force-sensitive units called ‘mechanophores’ to the middle of polymer strands. When a mechanical force is applied, the mechanophore undergoes a chemical reaction and turns into a different molecule.

It’s already known that mechanical forces can activate reactions by ‘tugging’ on reactant bonds, but usually this just ruptures the molecules. Critically, these new materials don’t break.