Recent developments in artificial molecular-machine-based active nanomaterials and nanosystems

Artificial molecular machines capable of converting chemical, electrochemical, and photochemical energy into mechanical motion represent a high-impact, fast-growing field of interdisciplinary research. These molecular-scale systems utilize a "bottom-up" technology centered upon the design and manipulation of molecular assemblies and are potentially capable of delivering efficient actuation at length scales dramatically smaller than traditional microscale actuators. As actuation materials, molecular machines have many advantages, such as high strain (40%-60%), high force and energy densities, and the capability to maintain their actuation properties from the level of a single molecule to the macroscale. These advantages have inspired researchers to develop molecular-machine-based active nanomaterials and nanosystems, including electroactive and photoactive polymers. This article will discuss the structures and properties of artificial molecular machines, as well as review recent progress on efforts to move molecular machines from solution to surfaces to devices.