Liquid crystal elastomer shells with topological defect-defined actuation: Complex shape morphing, opening/closing, and unidirectional rotation

We produce hollow sphere liquid crystal elastomer (LCE) actuators from a nematic precursor mixture, brought into the shape of self-closing shell with tangential anchoring director field n(r), using solvent-assisted microfluidic technique. By separating production polymerization and cross-linking, is allowed to approach its equilibrium n(r) configuration in shell, spontaneously forming topological defects total strength +2. However, photopolymerization an LCE induces brief but strong distortion overall defect configuration, even changing ground state case thick shells. The resulting shells show rich capacity for reversible morphing upon heating cooling, exact actuation mode defined by final stabilized at end polymerization. In regions single +1 defect, reversal curvature concave convex found, punctured exhibit change between nearly closed low temperature open-ended spherocylinder high temperature, all rotate when suspended fluid. As rotation stronger during relaxation than actuation, thus breaking symmetry, net unidirectional.