Amphiphilic Janus particles feature the combination of two different functional materials in one single colloid, as well as the possibility of self‐assembly at interfaces into complex superstructures. In this article, the self‐assembly of dual temperature responsive amphiphilic Janus particles at liquid–liquid interfaces and their subsequent conversion into an actuating layer‐shaped surface are presented. These microparticles are produced in a capillaries based continuous flow microfluidic device by photoinitiated radical polymerization. The hydrophobic part of the Janus particles contains a liquid crystalline elastomer (LCE), which performs a strong actuation up to 95% during the nematic–isotropic phase transition. The other side consists of a p(NIPAAm) hydrogel, which features volumetric expansions up to 280% below the lower critical solution temperature. A multistep molding process is developed to uniformly align the Janus particles at a toluene/water boundary surface and to embed the particles into a hydrogel matrix. A particle covered hydrogel layer is obtained, which features a collective actuation of the rod‐like LCE parts on the surface and a bundling of the resulting forces during the phase transition.

Photoresponsive micrometer-sized liquid crystalline elastomer particles were synthesized in a microfluidic setup and showed a strong actuation by irradiation with light.

Photoactuating liquid crystalline elastomers (LCE) are promising candidates for an application as artificial muscles in microdevices. In this work, we demonstrate that by optimizing (1) the illumination conditions and (2) the mixture of azo monomer and azo crosslinker, thick films of an all-azo LCE can be prepared, which show a strong length change without bending during photoactuation. This becomes possible by working with white light (about 440 nm), whose absorption is low, leading to a large penetration depth. By adding an azo crosslinker to a previously prepared system, several improvements of the actuation properties-like a stronger photoactuation at lower operational temperatures-could be achieved. In addition, films of different crosslinker concentrations and thicknesses were produced by photopolymerization at varying temperatures within a magnetic field, and their thermo-and photoresponsive behavior was investigated. An extraordinarily strong maximal thermal actuation of 46% and-by exposure to white light at 70 • C-a photoresponsive change in length of up to 40% in just about 13 s could be obtained. Even densely crosslinked samples were still able to photoactuate remarkably. Isothermal back-deformation could either be achieved by irradiation with red light (7 min) or by keeping the film in the dark (13 min).

In this article the microfluidic synthesis and characterization of micrometer sized actuating Janus particles containing a liquid crystalline elastomer (LCE) is presented. On one side these Janus particles consist of a hydrophobic liquid crystalline part, featuring strong shape changes during the thermotropic phase transition, whereas the other side contains a hydrophilic polyacrylamide network. The synthesis is based upon the dispersion of two immiscible monomer mixtures in a continuously flowing silicone oil, using two glass capillaries side by side to form Janus microdroplets of different morphologies. Furthermore, the systematic adjustment of the morphology of the Janus particles as well as the optimization of the actuation properties is conducted by precise control and variation of the microfluidic parameters. The actuation properties of the particles are studied by polarized optical microscopy (POM), in which relative length changes up to 52% are investigated for the elongation of LCEs during the phase transition in rodlike Janus particles. Further wide-angle X-ray scattering (WAXS) measurements verify the mesogen's orientation in a bipolar director field, which corresponds to the observed geometry of the Janus particle's shape changes.

Long actuating tubes (both thermo- and photo-responsive) made of liquid crystalline elastomers can be prepared in a microfluidic setup.