Chemists know how to set off chemical reactions by adding an adjuvant -a catalyst- and activating it by raising the temperature, but so far researchers have not succeeded in making a catalyst active through mechanical forces. The breakthrough was published on 6 April on the site of the new journal Nature Chemistry.

The TU/e team, consisting of dr. Alessio Piermattei, dr. Karthik Sivasubramanian and prof. dr. Rint Sijbesma, enveloped a catalyst (a metal ion) by means of two molecular caps, to which they attached a long polymer tail (see illustration). They dissolved all of this in a liquid. In the liquid the researchers then applied ultrasound to create a strong flow, which pulled on the polymer chains hard enough to separate the molecular caps from the metal ion, enabling this ion to do its work as a catalyst.

Similar constructions could be built into all kinds of materials, Sijbesma expects. In the event of a fracture developing, a catalyst would then also be released automatically that can repair the material via a polymerization reaction –whereby long chains arise from available building blocks. Sijbesma: “For me as a chemist it is wonderful to see that we can now control catalytic activity, one of the basic concepts of chemistry, through mechanical forces. In addition to self-repairing materials, you could also apply this in lab-on-a-chip systems or injection molding processes in the industry.”/.