Polymer-based actuators: back to the future

Abstract

<p>This work demonstrates that polymer-based actuators play a key role in the area of smart materials and devices.</p>

Colossal expansion and fast motion in spin-crossover@polymer actuators

“…44 From these beam bending experiments (see the ESI † for details), the strain and work density associated with the SCO was evaluated as e SCO = 1.1% and W/V SCO = 0.09 J cm À3 , respectively. These values are significant with respect to other classes of soft actuators, [9][10][11][12][13][14][15][16][17][18] which was showcased by fabricating a gripper device using three bilayers of 1a (see the ESI †). Yet, it appears necessary, in particular for robotics applications, to further increase the work output of our actuators.…”

“…[6][7][8] The most investigated active materials for soft actuators comprise dielectric elastomers, conductive polymers, piezo/ferroelectric materials, stimuli-responsive gels, coiled/twisted polymer fibers and yarns, shape memory materials, fluid-driven materials and photoisomerizable organic polymers. [9][10][11][12][13][14][15][16][17][18] Depending on the physical mechanisms underlying the actuation, they can be operated by different stimuli, including electric fields, temperature, pressure, magnetic field, humidity or light irradiation.…”

Environmentally friendly carrageenan-based ionic-liquid driven soft actuators

“…In particular, smart materials are able to convert an electrical stimulus into a mechanical response, leading therefore to suitable actuator responses 9 . Polymer-based actuators, typically, identified as soft actuators, have gained increasing attention in areas including biomedicine, packaging, factory automation, microelectronics, or robotic, among others 10 . To improve actuator performance or even to add further functionalities, fillers such as ionic liquids (ILs) are being explored 11 .…”

“…Recently, the potential of carrageenan hydrogels as actuators has been demonstrated [43], the use of different types of carrageenan (κ, ι, and λ) combined with poly(3-hexylthiophene) (P3HT) allowing to tailor the electrical and electrochemical properties of neat carrageenan hydrogels [43]. However, besides the great interest on soft actuators, natural polymers and ILs, the area of natural polymer based soft actuators is an emergent one, with a lack of studies concerning the suitable combination of natural polymers and ILs, despite its great potential in tuning materials properties and functional performance 11,35 . Imidazolium-based ILs and epoxidized natural rubber (ENR), able to improve the polymers heat resistance and electrical conductivity showed potential in application as elastomeric sensors and actuators 36 .…”

All printed soft actuators based on ionic liquid/polymer hybrid materials

“…Piezoelectric actuators show low deformation and mainly high frequency response, requiring typically large driving voltages [36], being therefore limited for some applications. Thus, a new generation of large deformation, low frequency and low voltage actuators are being developed, the most promising approaches being based on ILs introduced in a polymer matrix [36].…”