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Soft actuation materials often only perform an actuation function, and do not achieve the function of self‐sensing. In this work, the polyvinyl chloride (PVC) gels are prepared with a plasticizer of dibutyl adipate (DBA) and small amount of imidazolium type ionic liquids (ILs), and are demonstrated that the PVC/DBA/ILs gels deliver the integrated bending actuation and capacitance pressure self‐sensing capability. The bending actuation performances and sensing behavior of PVC/DBA/ILs are related to the migrability of movable ions from ILs, which are dependent on the dissociation of anions and cations of ILs, and the concentration of ILs. Among the ILs, the PVC/DBA gel with 3.3 wt% 1‐allyl‐3‐methylimidazolium bis ((trifluoromethyl)sulphonyl) imide (P/[AMIM]NTF2 (3.3 wt%)) exhibits best bending displacement of 6.6 mm (corresponding to 24° of bending angle) at 7.2 kV (180 V mm−1 of nominal electric field). In addition, the P/[AMIM]NTF2 (3.3 wt%) exhibits 0.42 kPa–1 capacitance pressure sensitive in the pressure range 0 to 2.2 kPa, and a sudden change in capacitance in the pressure range 2.2–2.7 kPa with 47.5 kPa–1 of sensitivity. The results can provide a new idea for developing integrated sensing and actuation functions of electroactive dielectric polymer gels. [ABSTRACT FROM AUTHOR]

The poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) gel which a type of electroactive thermoplastic elastomer has significant intrinsic electromechanical coupling effect owing to its unique microphase separated structure. However, the relationship between the structure and electromechanical properties of SEBS gel remains incompletely understood. This study investigates the effects of polar groups and nanostructure parameters on the bending electromechanical property of SEBS gel for improving its bending electromechanical properties, using maleic anhydride-grafted SEBS/white oil (WO) gel (SEBS-M gel) and blends of SEBS-M gel with acrylonitrile-styrene copolymer (SAN). The SEBS-M gel/SAN films exhibited a hexagonally packed cylinder (HEX) morphology, and the radius of polystyrene domains (r PS) as well as the thickness of poly(ethylene-co-butylene) (PEB) domains (d PEB) in the SEBS-M gel/SAN slightly decreased with increasing SAN content up to 15 phr, followed by an increase. The bending displacement and actuation stress of SEBS-M gel/SAN increased with increasing SAN content up to 15 phr. The bending displacement of SEBS-M gel at 1.4 kV is approximately 74 % of that of SEBS gel, while the bending displacement of SEBS-M gel/SAN-15 at 1.4 kV is approximately 195 % and 266 % higher than that of SEBS gel and SEBS-M gel when the SAN content reaches 15 phr, respectively. The grafted maleic anhydride has a counteractive effect on the bending electromechanical properties of SEBS gel, while blending with a certain amount of SAN in SEBS-M gel has a synergistic effect on the bending electromechanical properties of SEBS gel. It is demonstrated that the enchantment of bending electromechanical properties of SEBS gel is achieved not only by adjusting the parameters of its microphase-separated structure but also by inducing segment deformation through electric field-induced dipole orientations. [Display omitted] • The effects of polar groups and nanostructure on the bending electromechanical property of SEBS gel were investigated. • Blending with a certain amount of SAN in SEBS-M gel improve the bending electromechanical properties of SEBS gel. • The dipole orientations significantly influence the bending electromechanical properties of SEBS gel. [ABSTRACT FROM AUTHOR]

Abstract Poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE), poly(vinylidene fluoride-co-hexafluropropylene) (PVDF-HFP) and poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) were evaluated for the development of ionic liquid (IL) - polymer composite bending actuators. The selected guest IL, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [Emim][TFSI], was incorporated into the different host polymer matrixes in concentrations ranging from 10 to 40 wt%. The IL/polymer composites electrical properties strongly depend on the IL content. The largest bending response was found for the IL/PVDF-TrFE composites with a maximum bending value of ∼3.5 mm using a frequency of 100 mHz at an applied potential difference of 5.0 V pp. Thus, PVDF-TrFE are attractive candidates for the development of high performance bending actuators. Graphical abstract Image 1 Highlights • [Emim][TFSI] composite films with PVDF and copolymers were prepared. • [Emim][TFSI] contents up to 40%wt were used. • The films were evaluated as bending actuators. • Polymer chain plays an important role in the bending response. • The largest bending response (∼3 mm) was obtained for a PVDF-TrFE composite. [ABSTRACT FROM AUTHOR]

Highlights • Photoactive dopant DNSA in PPy electropolymerization. • PPy/DBS as reference, PPy/DBS-DNSA, PPy/DNSA bilayer. • Displacement of PPy bilayer before and after solar irradiation. Abstract A new methodology to increase the polypyrrole (PPy) bilayer actuation displacement is presented, based on photo-activated dopants generating secondary charges. Two dopants, dodecyl benzenesulfonate (DBS) and the photo-active dopant 2-diazo-1-naphthol-5-sulfonic acid (DNSA), were compared in this study. PPy/DBS, PPy/DBS-DNSA and PPy/DNSA bilayers on polyethylene terephthalate were formed and their actuation properties in aqueous electrolyte were investigated applying cyclic voltammetry and square wave potential steps. Exposure to solar irradiation increased PPy/DBS-DNSA and PPy/DNSA bilayer bending displacements by two and three times, respectively, accompanied by increased charge density during the reversible redox cycles. UV–vis and Fourier transform infrared (FTIR) measurements were also performed to follow the photo reaction of the photo-active dopants. [ABSTRACT FROM AUTHOR]

Mass production of conducting polymer actuators with reliable performance is envisaged in the field of artificial muscles. In this study, inkjet printing and spin coating – two established technologies for large-scale production – were combined for microactuator fabrication. Actuators based on poly(3,4-ethylenedioxy-thiophene):poly(styrene sulfonate) electrodes (PEDOT:PSS, 2.2 μm thick, 190 S cm −1 ), which were inkjet-printed onto a spin-coated membrane of an interpenetrating polymer network (IPN) thin film composed of nitrile butadiene rubber and poly(ethylene oxide) (PEDOT:PSS-IPN-PEDOT:PSS) with a total thickness of 12.7 μm, were prepared and studied. Our goal was to investigate the performance of the trilayers in linear actuation, in aqueous and organic (propylene carbonate) solutions of bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) used as electrolytes, and in bending actuation in air using an ionic liquid as the electrolyte. Electro-chemo-mechanical deformation (ECMD) measurements were consistent with electrochemical measurements showing a strain of 3% in aqueous electrolyte and 1% in propylene carbonate. A strain of 0.14% in the bending mode in the ionic liquid was observed due to electric double layer charging, while in electrolyte solutions, redox reactions determined the linear actuation properties. In the aqueous electrolyte, a specific capacitance of 193 F g −1 was measured for the printed PEDOT:PSS films, with potential for applications in supercapacitors. [ABSTRACT FROM AUTHOR]

Electronic conducting polymer based-actuators have attracted lots of interest as alternative materials to traditional piezoelectric and electrostatic actuators. Their specific characteristics such as their low operating voltages and large strains should allow them to adapt better to soft microstructures. Recently, poly (3,4-ethylenedioxythiophene) (PEDOT) – based ionic actuators have overcome some initial stumbling blocks to widespread applications in the microfabricated devices field. These trilayer bending microactuators were fabricated (i) by sequential stacking, using a layer by layer polymerization (LbL) of conducting polymer electrodes and a solid polymer electrolyte and (ii) by micro-patterning, using standard microsystems processes. While microfabrication processing of a trilayer actuator, involving no manual handling has been demonstrated, their bending performances remain limited for practical applications. Moreover, the complete characterization of their electrical, electrochemical, and mechanical properties has never been investigated. This paper describes the optimization of PEDOT electroactive electrodes synthesized with a vapor phase polymerization process. Influence of synthesis parameters on thickness, electronic conductivity and volumetric charge density were studied to determine the guidelines for synthesizing highly efficient electrodes. Afterwards, these parameters are used to guide the LbL synthesis process of ultrathin trilayer actuators. Electrochemical and mechanical properties of the resulting microactuators have been thoroughly characterized. Bending deformation and output force generation have been measured and reached 0.5% and 11 μN respectively. This constitutes the first characterization of ionic PEDOT-based microactuators operating in air of such a thin thickness (11 μm dry and 18.3 μm swelled in 1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMImTFSI)). These actuators and their actuation properties are promising for future soft microsystem devices where the use of polymer actuators should be essential. [ABSTRACT FROM AUTHOR]

Dielectric elastomers (DEs) as one class of electronic type of electroactive polymers (EAPs) can be deformed under electrical stimulation, and have important applications in the soft robots, wearable electronic devices, and medical rehabilitation machinery so on. In this work, the bending actuation mechanism, and electromechanical properties of nanostructured dielectric poly (styrene-b-(ethylene-co-butylene)-b-styrene)/white mineral oil (SEBS/WO) blend films were investigated under free electrodes condition. The morphology and mechanical properties of SEBS/WO films were adjusted by the content of WO, where the WO selectively swelled the poly (ethylene-co-butylene) (PEB) domains. The phase transition of lamellar (LAM) structure to hexagonal array packed cylinder (HEX) of SEBS/WO films was observed when added WO content larger than 17 wt%. The modulus and the polystyrene (PS) domain radius of SEBS/WO blend films with HEX structure were decreased as increase of WO weight fraction. The bending displacement of SEBS/WO films was almost linearly dependent on the applied electric voltages, and the single cantilever model based calculated bending force was almost linearly dependent on inverse of PS domain radius for SEBS/WO films with HEX morphology. The bending actuation mechanism of SEBS/WO films with HEX morphology was suggested that the bending actuation of SEBS/WO films was caused by electrostatic attraction force between inter-PS domains induced squeezing deformation of poly (ethylene-co-butylene) (PEB) domains. The SEBS/WO blend films with 50 wt% of WO content showed 6.54 mm (corresponding to 23.56°) at 2 kV (50 V/mm of nominal electric field). Our results can provide new insight on development of nanostructured electroactive elastomers for applications in the soft actuator materials. [Display omitted] • Dynamic electromechanical performances and mechanism of SEBS/white mineral oil (WO) films were investigated. • The bending force of SEBS/WO films with HEX morphology was almost linearly dependent on inverse of PS domain radius. • SEBS/WO films have fast response rate and are high stability. • Electrostatic attraction force between inter-PS domains induces squeezing deformation of PEB domains. [ABSTRACT FROM AUTHOR]

Electroactive dielectric polymer gels (DPGs) have important applications in soft robots, wearable electronics, and biomedical devices etc. However, the relationship between structure and electromechanical properties of DPGs have not been fully understood so far. In this work, the effect of the bi-component plasticizers on the structure, mechanical properties, dielectric properties, and electric field induced dynamic bending actuation behaviors of plasticized poly (vinyl chloride) (PVC) gels with free electrodes were investigated using the dibutyl adipate (DBA) as major plasticizer and the branch structured bio-based triethyl 2-acetylcitrate (ATEC) or triethyl citrate (TEC) as minor second plasticizer (30 wt% of bi-component plasticizer). The PVC gel films bend towards the anode side when applied electric field under free electrodes measurement condition. The electric field induced capacitance change of PVC gels was important factor to influence the bending displacement, which were influenced by the interactions between plasticizers and PVC chains in PVC gels. The bending displacement of PVC/DBA/TEC and PVC/DBA/ATEC gels is about 80% and 140% of PVC/DBA at 7.2 kV (corresponding to 180 V/mm of nominal electric field), respectively. The synergistic and counteractive effects of bi-component plasticizers on the bending actuation of PVC gels are mainly attributed to the competition between plasticization effect of PVC and interactions of inter-plasticizers. Our results provide a new insight for the design of high performance electroactive dielectric polymer gel materials. • Electric field-induced dynamic bending actuation performances of plasticized PVC gels with free electrodes were enhanced by bi-component plasticizer. • Competition between interactions of plasticizers and PVC and interactions of inter-plasticizers is key factor to influence the bending actuation of PVC gel. • The electric field induced bending of PVC gels was caused by asymmetric charges accumulation on the both surfaces of PVC gel films. [Display omitted] [ABSTRACT FROM AUTHOR]

Compliant electrodes (CEs) were prepared from deproteinized natural rubber (DPNR) and multi-walled carbon nanotubes (MWCNTs) using Triton X-100 as a dispersing agent. Dielectric elastomers (DEs) were fabricated, from the DPNR incorporated with functionalized MWCNTs as a high dielectric constant filler, by film casting and the UV-curing process. The effect of MWCNT concentrations on mechanical and electrical properties of the CEs and DEs were individually examined. The defection responses and the dielectrophoresis forces of DEs and DEs attached on one side with CEs (DEs/CEs) were investigated as functions of electric field strength. The 5% v/v MWCNTs composite (CE_5) showed the highest conductivity of 19.7 S/cm and was subsequently used in the DEs/CEs bending experiment. The 2.5 phr of functionalized MWCNTs composite (DE_2.5) showed the highest dielectric constant of 15.4, but a relatively low bending actuation due to its initial high rigidity. The DE_1/CE_5 bilayer composite possessed the highest bending actuation, namely the largest bending distance and the dielectrophoresis force, presumably from the additional polarizations within CE_5 and the interactions with DE_5. [Display omitted] • The bending actuations of dielectric elastomers (DEs)/compliant electrodes (CEs) composites were tested in the air medium. • Pristine DPNR with a thinner dielectric layer was shown to swing back and forth under constant electric fields. • The 5% v/v MWCNTs composite (CE_5) showed the highest electrical conductivity of 19.7 S/cm. • The DE_1/CE_5 possessed the highest dielectrophoresis force and density. • The fabricated bilayer composites were shown here to be a promising electroactive material for soft actuator applications. [ABSTRACT FROM AUTHOR]

Highlights from the article: Photothermal Actuators: Photothermal Bimorph Actuators with In-Built Cooler for Light Mills, Frequency Switches, and Soft Robots (Adv. Funct. Keywords: bending actuation; light mills; photothermal; soft robots; torsional actuation In article number 1808995, Zunfeng Liu and co-workers develop a tri-layered bimorph actuator that shows a fast response, large bending amplitude, and small temperature change.

Photothermal bimorph actuators are widely used for smart devices, which are generally operated in a room temperature environment, therefore a low temperature difference for actuation without deteriorating the performance is preferred. The strategy for the actuator is assembling a broadband‐light absorption layer for volume expansion and an additional water evaporation layer for cooling and volume shrinkage on a passive layer. The response time and temperature‐change‐normalized bending speed under NIR, white, and blue light illumination are at the same level of high performance, fast photothermal actuators based on polymer or polymer composites. The classical beam theory and finite element simulations are also conducted to understand the actuation mechanism of the actuator. A new type of light mill is designed based on a wing‐flapping mechanism and a light‐modulated frequency switch. A fast‐walking robot (with a speed of 26 mm s−1) and a fast‐and‐strong mechanical gripper with a large weight‐lifting ratio (≈2142), respectively, are also demonstrated. [ABSTRACT FROM AUTHOR]