Multitemperature Memory Actuation of a Liquid Crystal Polymer Network over a Broad Nematic-Isotropic Phase Transition Induced by Large Strain

The shape change of a polymer actuator based on liquid crystal network (LCN) generally occurs over a relatively sharp LC-isotropic phase transition. Reported herein is the discovery of an unusual phenomenon and the enabled actuation control for LCN. The smectic phase of a LCN with mesogenic moieties on the chain backbone can be suppressed by high elongation of the specimen, which gives rise to a broad nematic-isotropic phase transition. Consequently, the actuation force and related shape of the actuator can be activated to a given degree by easily varying the temperature over a wide range (35 K for LCN prepared with 500% strain) to adjust the proportion of the order-disorder phase transition. This reversible multitemperature memory actuation can translate into many stable and interconvertible shapes with one single LCN actuator.