Mechanochemistry of Cubane.

We report the mechanochemical reactivity of the highly strained pentacyclic hydrocarbon cubane. The mechanical reactivity of cubane is explored for three regioisomers with 1,2-, 1,3-, and 1,4-substituted pulling attachments. Whereas all compounds can be activated thermally, mechanical activation is observed via pulsed ultrasonication of cubane-containing polymers only when force is applied via 1,2-attachment.

Substituent Effects in Mechanochemical Allowed and Forbidden Cyclobutene Ring-Opening Reactions.

Woodward and Hoffman once jested that a very powerful Maxwell demon could seize a molecule of cyclobutene at its methylene groups and tear it open in a disrotatory fashion to obtain butadiene (Woodward, R. B.; Hoffmann, R.

Mechanochemically Active Soft Robots.

The functions of soft robotics are intimately tied to their form-channels and voids defined by an elastomeric superstructure that reversibly stores and releases mechanical energy to change shape, grip objects, and achieve complex motions. Here, we demonstrate that covalent polymer mechanochemistry provides a viable mechanism to convert the same mechanical potential energy used for actuation in soft robots into a mechanochromic, covalent chemical response. A bis-alkene functionalized spiropyran (SP) mechanophore is cured into a molded poly(dimethylsiloxane) (PDMS) soft robot walker and gripper.

Molecular engineering of mechanophore activity for stress-responsive polymeric materials.

Force reactive functional groups, or mechanophores, have emerged as the basis of a potential strategy for sensing and countering stress-induced material failure. The general utility of this strategy is limited, however, because the levels of mechanophore activation in the bulk are typically low and observed only under large, typically irreversible strains. Strategies that enhance activation are therefore quite useful.