University of Sheffield researchers are developing synthetic molecular motors that simulate biological molecular motors, which operate by using molecular shape changes.

The researchers are using a polymer with weak acidic or basic groups along the backbone. For a polyacid, for example, in acidic conditions the molecule is uncharged and hydrophobic; it takes up a collapsed, compact shape. But when the acid is neutralised, the molecule ionizes and becomes much more hydrophilic, substantially expanding in size.