Rise or fall: Complex-structured freestanding polymer films with molecular order in three dimensions were prepared through photoalignment of polymerizable liquid crystals. The resulting films deform into cone and saddle shapes upon heating.
We show a versatile method for the preparation of a variety of humidity-responsive actuators based on a single sheet of a hydrogen-bonded, uniaxially aligned liquid crystal polymer network. In this approach, the asymmetry in the molecular trigger in the anisotropic polymer film plays a dominant role leading to programmed deformation events. The material is locally treated with a potassium hydroxide solution to create the asymmetry in the responsiveness toward humidity, which allows to prepare actuators that bend, fold, or curl.
This work describes the fabrication, characterization, and modelling of liquid crystalline polymer network films with a multiple patterned 3D nematic director profile, a stimuli‐responsive material that exhibits complex mechanical actuation under change of temperature or pH. These films have a discrete alternating striped or checkerboard director profile in the plane, and a 90‐degree twist through the depth of the film. When actuated via heating, the striped films deform into accordion‐like folds, while the film patterned with a checkerboard microstructure buckles out‐of‐plane. Furthermore, striped films are fabricated so that they also deform into an accordion shaped fold, by a change of pH in an aqueous environment. Three‐dimensional finite element simulations and elasticity analysis provide insight into the dependence of shape evolution on director microstructure and the sample's aspect ratio.
Auf‐ oder abwärts: Komplex strukturierte freistehende Polymerfilme mit einer dreidimensionalen molekularen Ordnung wurden durch Photoausrichtung polymerisierbarer Flüssigkristalle hergestellt. Die gebildeten Filme verformen sich beim Erhitzen zu Kegel‐ und Sattelformen.
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