Chemomechanics

an area of the physical chemistry of polymers concerned with the reversible conversion of chemical energy into mechanical energy resulting from the conversion of polymer macromolecules from one conformation to another. Any changes in the chemical potential of a medium in which a macromolecule is present causes a change in the conformation of the macromolecule, and, conversely, a change in macromolecular conformation as a result of a mechanical action on the conformation causes a change in the chemical potential of the medium (the teinochemical principle).

The best known manifestation of the teinochemical principle is observed during the swelling of polyelectrolytes: an increase in the degree of ionization of a polyelectrolyte leads to an increase in the size of the macromolecular coil, while a decrease in the degree of ionization leads to a decrease in size. A coil consisting of a polyelectrolyte that swells in water will regularly expand and contract with a periodic change in the water’s pH. It may perform mechanical work upon contraction, which is the basis of the chemical machine, or pH muscle. Such machines, which are designed to demonstrate the teinochemical principle, are capable of lifting a one-ton body.

The applications of the teinochemical principle are not only limited to energetics. Mechanical action on a polymer may alter the polymer’s ion-exchange and electron-exchange properties, reactivity, and catalytic activity.