Near‐Infrared Photodriven Self‐Sustained Oscillation of Liquid‐Crystalline Network Film with Predesignated Polydopamine Coating

Abstract

Movement is one of the vital features of living systems, and remote control of bioinspired soft robotic systems in a precise, contactless and harmless way is extremely desirable but challenging. A near‐infrared (NIR) photodriven polymeric oscillator is designed and fabricated by selectively coating a mussel‐inspired polydopamine (PDA) polymer layer on the surface of splay‐aligned liquid crystalline network (LCN) film. The oscillating motions of the LCN oscillators can be facilely manipulated by tuning light intensity and film thickness. More importantly, the programmability of the PDA coating enables the oscillating behaviors of LCN film to be predesignated and finely adjusted by coating the film with PDA locally and repeatedly. The self‐oscillating movement mechanism can be attributed to the temperature oscillation at the PDA‐coated LCN film since it is alternatively exposed and sheltered to the NIR‐light irradiations. Owing to over 50% NIR irradiation in solar spectrum, PDA‐coated film is found to oscillate upon exposure of focused sunlight, presenting great potential in fabrication of solar power generation devices. This provides a versatile strategy to fabricate NIR‐light‐actuated polymeric oscillators, providing inspirations in the development of biological soft robots and advanced biomimetic devices.

Light Tracking and Light Guiding Fiber Arrays by Adjusting the Location of Photoresponsive Azobenzene in Liquid Crystal Networks

“…[9] For photothermal actuation, a specific chromophore is often added to the system so that when illuminated with the proper wavelength, a mechanical response is generated. [10][11][12][13][14] Once the illumination stops, the actuator immediately returns to its initial state due to the reduction of the temperature. Thus, a constant energy supply is essential to preserve the desired transitional conformation.…”

Liquid Crystal Polymer‐Based Soft Robots

“…For example, as the photothermal component PDA can be facilely dip‐coated and also easily removed via alkaline washing, Yang and co‐workers endowed a splay‐aligned LCN film with predefined and reprogrammable self‐oscillation behavior by tuning the PDA coatings. [ 107 ] The film swinging with amplitude of 4.8 mm and frequency of 5.4 Hz was changed to oscillating 2.6 mm at 9.6 Hz when the PDA dip‐coating time was changed from 20 to 40 h.…”

Recent Advances in Photoactuators and Their Applications in Intelligent Bionic Movements

“…Moreover, the LCN and Azo-LCN films can be used as self-oscillating actuators under static light. [3,51,99] The oscillation depended on the absorption gradient in the Azo-LCN and trans-cis isomerization kinetics for the Azo-LCN. Reproduced with permission.…”