A solar actuator based on hydrogen-bonded azopolymers for electricity generation

167

117

Shape‐changing polymers are an emerging class of smart stimuli‐responsive materials. Among the different stimuli that could be used for polymer actuation, light has several especially attractive features, including precise spatial and temporal remote control, easily tunable properties, and on‐demand pausing and resuming of the actuation. Consequently, light‐responsive polymers offer potential solutions to many pressing technological problems, especially where a noncontact form of stimulation and control is desired. In this review, state‐of‐the‐art advancements in the field of light‐responsive shape‐changing polymers are highlighted. The systems are classified according to the material type and the underlying light‐driven actuation/shape‐change mechanism. Finally, the most promising applications for light‐driven polymeric actuators are outlined, followed by challenges in the area and outlook on future promising directions.

Section: Systems and Actuation Mechanismsmentioning

confidence: 99%

Section: Systems and Actuation Mechanismsmentioning

confidence: 99%

Light‐Responsive Shape‐Changing Polymers

Stoychev

Kirillova

Ionov

2019

167

117

“…Over the past few years, several different visible light responsive materials based on such azobenzenes have been developed 55d,57b,85. For example, together with the Schenning group we have developed a chaotic self‐oscillating sunlight‐driven polymer actuator ( Figure ),85d based on a tetra‐ ortho ‐fluoro azobenzene derivative (Figure a), which was integrated as a crosslinker into a splay‐oriented LC film (Figure b). Upon placing the freestanding film into ambient and “isotropic” sunlight, it immediately starts to bend (Figure c) and oscillate in a chaotic fashion as shown by plotting the temporal changes of the deflection angle (Figure d).…”

Section: Photoswitching Bulk Materialsmentioning

confidence: 99%

“…a) Molecular design of the photoswitch, b) splay‐orientation within the film, c) picture of the material under sunlight in front of a window, and d) plot of the deflection angle versus time during sunlight exposure through the window. Adapted under the terms and conditions of the Creative Commons Attribution License 4.085d Copyright 2016, The Authors, published by Springer Nature.…”

Section: Photoswitching Bulk Materialsmentioning

confidence: 99%

Designing Molecular Photoswitches for Soft Materials Applications

Boelke

Hecht

2019

132

In order to respond to light stimuli, materials and devices thereof must contain a photoresponsive component. Ideally, this response is reversible and can be tuned depending on the desired application. In the context of soft material development, the integration of molecular photoswitches has proven a viable strategy. This Progress Report outlines molecular design principles to successfully transfer beneficial photoswitching performance from solution to the bulk. Selected examples of the most prominently used classes of photoswitches and their use in actuating and self‐healing materials as well as optoelectronic and microfluidic devices are highlighted. The current state of the art is critically discussed with emphasis on both the scientific challenges and the future promise for light‐responsive, smart soft matter technologies.

“…Nature's array of stimuli‐responsive systems and organisms remain a constant source of inspiration for scientists in the development of soft actuators. Stimuli‐responsive materials exhibiting remotely powered actuation have potential applications in a variety of fields, ranging from soft/microrobotics, energy generation, microfluidic, and medical devices . Moreover, the integration of multitriggered responsive actuation into single devices is of interest for the next‐generation smart materials and is desired for untethered multi‐responsive soft robotics, opening a new range of applications, expanding from remotely controlled motion to possible locomotion.…”

Section: Introductionmentioning

confidence: 99%

An Untethered Magnetic‐ and Light‐Responsive Rotary Gripper: Shedding Light on Photoresponsive Liquid Crystal Actuators

Cunha

Foelen

Raak

et al. 2019

materials and is desired for untethered multi-responsive soft robotics, opening a new range of applications, expanding from remotely controlled motion to possible locomotion. However, a facile approach to combining multi-stimulus response into one device without imposing dramatic mechanical or chemical changes to the system remains a challenge. Grasping devices making use of stimuli-responsive actuation have already been reported [9][10][11][12][13][14][15] and a present goal in this field is to free these stimuli-responsive soft robotic grippers from the necessity of manual manipulation for movement.Combining soft materials and stimuliresponsive reagents for the development of functional materials is a present endeavor. [16] Liquid crystal networks (LCNs) are attractive materials for fabricating soft actuators since they operate in dry environments, and their deformation can be programmed within the LC network by the 3D organization of the molecular building blocks. The versatility of liquid crystal (LC) networks has allowed for the development of several functional, responsive actuators with diverse fabrication techniques, such as 3D printing, [17] and operating with a variety of triggers, including light, [18][19][20][21][22] heat, [23] humidity, [24,25] and magnetic, [26,27] and electric [28] fields. Among the triggers studied in the development of LC actuators, light is highly appealing for untethered motion as it provides instantaneous stimulus, resulting in a fast response Here, a remotely controlled dual magneto-and photoresponsive soft robotic gripper is reported, capable of loading, transport, rotation, and release of cargo. The untethered soft actuator consists of a magnetically responsive polydimethylsiloxane layer containing magnetic iron powder coated onto the central region of a light-responsive liquid crystal polymer film hosting photochromic azobenzene dyes. Light is used to trigger the actuator to autonomously grab and pick up cargo with a high degree of control. Magnetic response is employed to conduct the locomotion as magnetic guidance, allowing the gripper to have both translational freedom and rotational freedom in its locomotion, differentiating the device from other soft robotic grippers. Control can be attained even in enclosed and/or confined spaces, through solely remote actuation. Through combined video, mechanical, and thermal analyses, the actuation mechanism of the light-responsive liquid crystal network is investigated, shedding light on the decisive role of the temperature evolution in governing both rate of motion and deformation amplitude of the light-responsive soft actuator.