Polymer mechanochemistry: the design and study of mechanophores

The burgeoning field of polymer mechanochemistry has garnered significant interest in recent years. Mechanochemical transformations are those that are promoted by exogenous forces, and polymer mechanochemistry concentrates on the use of polymer chains to translate mechanical forces to chemical systems. Acoustic fields, particularly ultrasound, have proven to be highly efficient progenitors of tensile stresses within macromolecules and are frequently used to facilitate mechanochemical phenomena. Mechanochemical activation often arises when mechanophores, or functional groups that respond to mechanical perturbation in a controlled manner, are appropriately positioned within a polymer chain to experience tensile forces. A variety of interesting transformations have been realized when well-designed mechanophores have been properly outfitted with polymer chains, including: thermally inaccessible isomerizations and cycloreversions, symmetry-forbidden electrocyclic ring openings and activation of latent catalysts. Herein, the chemistry of known mechanophores is summarized and augmented with implications for new opportunities in synthesis and materials science. The focus of this mini-review is limited to mechanophores that have been specifically adapted for polymer mechanochemistry under acoustic activation. (C) 2012 Society of Chemical Industry