David Leigh (The University of Manchester）Orderly Molecular Entanglements
Liquid crystals are known for their well-controlled molecular organization which is used to the benefit of liquid crystal displays, diffractive optics, soft robotics, and active surfaces. For most applications the liquid crystal alignment, as defined by the director, is chosen to be linear, twisted, splayed, or organized around a defect. When chirality is introduced to the liquid crystal, the molecular organization becomes more complex as the director field becomes nonuniform. In its most simple form, the director describes a continuous twist to form a helix. But also more spatially distorted structures are possible, such as double twisted helices, skyrmions and torons. In our work we combine these structures with motor molecules that change conformation or orientation upon activation by an external trigger, usually light or electricity. By coordinated interactions within the liquid crystal phases the molecular conformational changes are amplified to effects that can be seen, can be felt and can perform mechanical actions of relevance for our macroscopic world. Tangible materials are obtained by polymerizing the liquid crystals in their ordered state to a plastic film or object. In the presentation we will discuss the principles and place them in the perspective of applications such as information windows, haptic surfaces, pick-and-place elements, soft robotics and surface effects for lubrication and debris removal.