Light-fueled molecular machines can move matter

摘要

Photoisomerization induced molecular motion in azo polymers is an area of research that witnessed intensive studies owing to its potential in optical manipulation. In this paper, we give an overview of the theory of matter motion induced by photoisomerization. We show that besides photoisomerization, a gradient of light intensity is necessary to generate motion; e.g. generate a photoisomerization force to move matter. In concept, matter motion is due to competing forces, including viscous and photoisomerization forces, and possible radiation pressure and elastic forces, as well as a random force due to thermal fluctuations. In solid films of azo-polymers, the photoisomerization force overcomes other forces due to softening and decrease of viscosity of the material by photoisomerization.