Among different kinds of photoactuators available, those based on liquid‐crystal polymer networks (LCNs) are gathering a great deal of attention due to their fast response and versatility of structural design. However, only a few reports have focused on the phototriggered LCN actuators for complex actuation and multifunction properties. Here, a phototriggered LCN‐based photonic actuator with quasi‐bilayer structure that exhibits fast and reversible shape changes is created by infiltrating a LCN precursor–graphene oxide mixture into a silica opal template, ultraviolet photopolymerization, and removing the template. Particularly, the phototriggered selective actuation behavior is achieved in dual‐phase LCN‐based photonic actuators with macroscopically alternating nematic (N) and isotropic (I) phase, which enables versatile actuation modes and allows multiple shape changes. In addition, a two‐segmented, dual‐phase LCN‐based photonic actuator exhibits self‐oscillating motion when a responsive N‐phase region as localized active point is irradiated, which arises from the self‐shadowing of the passive I‐phase region. To demonstrate the potential application of this self‐oscillating motion behavior, a photoelectric energy conversion device that is capable of converting light energy to electric energy is constructed.

Transducing light into electricity in photoactive materials and composites is especially attractive for light sensing and light energy harvesting. Here, we present a near-infrared (NIR) light-triggered pyroelectricbased generator by integrating a photoresponsive composite actuator composed of a liquid crystal elastomer (LCE) and graphene-doped poly(dimethylsiloxane) (PDMS) into a polyvinylidene fluoride (PVDF) film, which can effectively convert photothermal and mechanical energy into electricity. Notably, a NIR light photothermal-triggered pyroelectric effect leads to outstanding electric output performance resulting from the large temperature fluctuation induced by the contact and separation between the LCE-based composite actuator and PVDF film upon turning on or off the NIR illumination. In addition, the photothermal pyroelectric property arising from the thermal fluctuations makes the hybrid generator highly suitable as a self-powered NIR light and temperature sensor. This light-driven LCE-based hybrid generator opens a new opportunity for developing novel power generators and active sensors. rsc.li/rsc-advances 40856 | RSC Adv., 2018, 8, 40856-40865 This journal is

We propose a novel shape and optical memories of a photonic composite film based on a silica opal photonic crystal (PC) template and a liquid crystal polymer network (LCN). Here, the photonic composite film was fabricated by introducing a LCN precursor into a silica opal PC template, followed by UV photo-polymerization and then by the removal of the template. The obtained bilayer-structure photonic film was found to spontaneously form a three-dimensional (3D) temporary bending shape in response to heating, and thus the corresponding reflection color of the photonic composite film shows a blue shift during bending deformation. The inherent mechanisms of these two observations could be attributed to the variations of the LC molecule orientation and the light reflection in the photonic composite film during the thermal process. More intriguingly, the resulting temporary bending shape was fixed by applying mechanical force during slowly cooling down to the room temperature or autonomously fixed by a rapid cooling in liquid nitrogen. Additionally, this temporary state could restore back to the permanent flat shape when the film is cooled from the heat source without an external force. Finally, more complex 3D shape-memory samples could also be achieved by simply controlling the LC alignment or designing the sample geometry. This work opens up a new way to develop a novel shape-memory polymer photonic film.

The chemiluminescent mechanophore, 1,2-dioxetane (Ad), is incorporated into the backbone of a polyurethane-based prepolymer, which is further end-capped with dimerizable strong hydrogen bonding units, ureidopyrimidinone and pyrimidinedione (UPy, DHB-2) or hydrogen bonding free unit (EtOH). Mechanical, optomechanical measurements, and small-angle/wide-angle X-ray scattering (SAXS/WAXS) analyses of these end-functionalized polyurethanes have demonstrated that the difference in the strength of hydrogen bonding interactions led to different degrees of chain orientation in the bulk, and consequently, different levels of mechano-activation of Ad with distinguishable mechanochemiluminescence intensity. This study not only offers a straightforward way to enhance the mechanochemiluminescence of Ad containing polymers by tailoring the supramolecular interactions between different macromers but also deepens our understanding of the correlations between chain orientation behavior, magnitudes of hydrogen bonding interactions, and the activation of mechanophores.