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Photoplastic Self-Healing Polyurethane Springs and Actuators

“…Smart actuators or artificial muscles that respond to external stimuli with changes in shape or size have recently attracted considerable attention. − Polymers play an important role in these smart materials as they provide several key advantages such as low manufacturing cost, the ease of processing, flexibility, low density, and so forth . Reversible stimuli-responsive smart polymeric elastomers containing photochromic molecular motifs, such as azobenzenes, spiropyrans, naphthopyran, and diarylbibenzofuranones, were investigated as sensors and actuators. − The distinguished molecular architectural transformation based on the mechanisms such as cis–trans isomerization and cyclization/cycloreversion upon light irradiation has been reported to control the fluorescence, conductivity, and fluidic properties of materials. − Compared with popular photochromic molecules, hexaarylbiimidazole (HABI) undergoes photoinduced cleavage of the C–N bond of two triphenylimidazoles upon light irradiation to give a pair of isolated triphenylimidozole radicals (TPIRs), which can undergo spontaneous annihilation upon encountering adjacent radicals. , Honda and Toyota synthesized the solvent-free HABI cross-linking polymer networks showing isothermal reversible liquid–nonliquid conversion, while the synthesis procedures involving star-shaped precursors are relatively complicated, and subsequent oxidation cross-linking efficiency of triphenylimidozoles is limited .…”

Micron-Sized Main-Chain Liquid Crystalline Elastomer Actuators with Ultralarge Amplitude Contractions

“…Materials scientists are increasingly turning to nature as a source of inspiration to develop new devices mimicking the structure and function of real biological systems. − Research regularly points out that many phenomena encountered in nature, such as the self-cleaning properties of lotus and rice leaves, the “sticky feet” of geckos, the vivid colors of the butterfly wings, or the drag-reducing surface of shark skin to name a few, are related to the specific micro and nanostructures of the involved surfaces. The search for smart materials, also called actuators or artificial muscles, that respond to external stimuli with changes in shape or size has recently attracted considerable attention from the material research community. , Polymers play a leading role in the domain of smart materials because they provide several key advantages: low manufacturing cost, high processability, flexibility, relatively low weight density, , etc. Combining these two domains, smart materials and solid surfaces with special properties (low friction, specific optical properties, etc.…”

Exploring stimuli-responsive elastin-like polypeptide for biomedicine and beyond: potential application as programmable soft actuators

“…It is truly fascinating to know that soft actuators based on EAP and thermoresponsive polymers are largely inspired based on human physiology. The movement of muscle tissue, contraction and relaxation of myofibers, is governed by the electrical signals relayed via neural network connected by neuromuscular junction, which is essentially the basis for EAPs Hannaford et al (2001) ; Cui et al (2020) . A lesser-known fact about thermoresponsive polymer is that several types of bodily tissues also make use of a naturally thermoresponsive, fibrous protein, called elastin, to impart mechanical compliance and elasticity.…”