Making waves in a photoactive polymer film
By A. Gelebart, D. Mulder, Michael Varga, Andrew Konya, G. Vantomme, E. Meijer, R. Selinger, D. Broer. Nature, 2017
898 citations recorded by the source corpus.
Oscillating materials that adapt their shapes in response to external stimuli are of interest for emerging applications in medicine and robotics. For example, liquid-crystal networks can be programmed to undergo stimulus-induced deformations in various geometries, including in response to light. Azobenzene molecules are often incorporated into liquid-crystal polymer films to make them photoresponsive; however, in most cases only the bending responses of these films have been studied, and relaxation after photo-isomerization is rather slow. Modifying the core or adding substituents to the azobenzene moiety can lead to marked changes in photophysical and photochemical properties, providing an opportunity to circumvent the use of a complex set-up that involves multiple light sources, lenses or mirrors. Here, by incorporating azobenzene derivatives with fast cis-to-trans thermal relaxation into liquid-crystal networks, we generate photoactive polymer films that exhibit continuous, directional, macroscopic mechanical waves under constant light illumination, with a feedback loop that is driven by self-shadowing. We explain the mechanism of wave generation using a theoretical model and numerical simulations, which show good qualitative agreement with our experiments. We also demonstrate the potential application of our photoactive films in light-driven locomotion and self-cleaning surfaces, and anticipate further applications in fields such as photomechanical energy harvesting and miniaturized transport.
Subfields: Electronic, Optical and Magnetic Materials, Materials Chemistry, Mechanical Engineering
View Paper: https://www.semanticscholar.org/paper/207e552c2f0e6e7c070684509bd4e524f50caf22
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Citations in the corpus
- From nanoscopic to macroscopic photo-driven motion in azobenzene-containing materials (2018, background): “Such effect is very promising for the realization of remotely controlled light-driven devices exhibiting interesting functionalities, like self-cleaning and self-propelling directional locomotion [342, 344].”
- Electrospun liquid crystal elastomer microfiber actuator (2021, background): “Although several self-oscillating LCE structures have been designed and fabricated, most of them are triggered by light via self-shadowing effect (35, 39).”
- Bioinspired underwater locomotion of light-driven liquid crystal gels (2020, neutral): “Previously, the relatively accurate spatiotemporal control over molecular alignment and programmable shape morphing of LCNs and LCEs have enabled numerous terrestrial robot locomotion systems in dry conditions, such as walking (28), crawling (29, 30), and jumping (31).”