Abstract
The need for mechanical manipulation during the curing of conventional liquid crystal elastomers diminishes their applicability in the field of shape-programmable soft materials and future applications in additive manufacturing. Here we report on polymer-dispersed liquid crystal elastomers, novel composite materials that eliminate this difficulty. Their thermal shape memory anisotropy is imprinted by curing in external magnetic field, providing for conventional moulding of macroscopically sized soft, thermomechanically active elastic objects of general shapes. The binary soft-soft composition of isotropic elastomer matrix, filled with freeze-fracture-fabricated, oriented liquid crystal elastomer microparticles as colloidal inclusions, allows for fine-tuning of thermal morphing behaviour. This is accomplished by adjusting the concentration, spatial distribution and orientation of microparticles or using blends of microparticles with different thermomechanical characteristics. We demonstrate that any Gaussian thermomechanical deformation mode (bend, cup, saddle, left and right twist) of a planar sample, as well as beat-like actuation, is attainable with bilayer microparticle configurations.
Highlights
The need for mechanical manipulation during the curing of conventional liquid crystal elastomers diminishes their applicability in the field of shape-programmable soft materials and future applications in additive manufacturing
We present a new composite material, polymer-dispersed liquid crystal elastomer (PDLCE) that overcomes the above restrictions: it provides for moulding of soft elastomeric bulk or miniature, thermally morphable parts of any given shape
The availability of nematic monodomain mLCEs is mandatory for the design of PDLCEs
Summary
The need for mechanical manipulation during the curing of conventional liquid crystal elastomers diminishes their applicability in the field of shape-programmable soft materials and future applications in additive manufacturing. We report on polymer-dispersed liquid crystal elastomers, novel composite materials that eliminate this difficulty Their thermal shape memory anisotropy is imprinted by curing in external magnetic field, providing for conventional moulding of macroscopically sized soft, thermomechanically active elastic objects of general shapes. The latter is accomplished by curing the mixture of polymer resin and mLCE in external magnetic field, exploiting the diamagnetic anisotropy of the mLCEs29 Since these are small with respect to the size of the composite specimen, inhomogeneities in local stress and strain can be disregarded, and the composite’s effective elastic and thermomechanical properties resemble those of a conventional bulk, oriented LCE material. We demonstrate that this paves the path towards designing thermomechanically functionalized conventional elastomers with tailorable shape memory and thermal expansion behaviour
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