Tunable Mechanical Response from a Crystal Undergoing Topochemical Dimerization: Instant Explosion at a Faster Rate and Chemical Storage of a Harvestable Explosion at a Slower Rate

Abstract

Strain developed in crystals in response to stimuli causes mechanical response. Methods to tune such mechanical response is important for practical applications. Crystals of a monomer having azide and alkyne units pre-organized in a ready-to-react orientation, undergo thermal topochemical dimerization and show rate-dependent mechanical response. When the reaction rate is fast, the crystals explode violently. When the reaction rate is slow, the crystals absorb water from the surroundings contemporaneously with the reaction to form the dimer-hydrate in a single-crystal-to-single-crystal (SCSC) manner. Crystals of the dimer-hydrate upon dehydration also undergo explosion. Thus, at slow reaction rate, the strain gets stored in crystals by hydration and the explosion can be harvested, at will, by dehydration. Use of this rate-dependent explosion in the automatic activation of a remedial electrical circuit in case of a sudden rise in temperature has been demonstrated.

Keywords: cycloaddition; dimerization; electrical switches; exploding crystals; mechanical response.