Electroactive Artificial Muscles Based on Functionally Antagonistic Core-Shell Polymer Electrolyte Derived from PS-b-PSS Block Copolymer.

Electroactive ionic soft actuators, a type of artificial muscles containing a polymer electrolyte membrane sandwiched between two electrodes, have been intensively investigated owing to their potential applications to bioinspired soft robotics, wearable electronics, and active biomedical devices. However, the design and synthesis of an efficient polymer electrolyte suitable for ion migration have been major challenges in developing high-performance ionic soft actuators. Herein, a highly bendable ionic soft actuator based on an unprecedented block copolymer is reported, i.e., polystyrene-b-poly(1-ethyl-3-methylimidazolium-4-styrenesulfonate) (PS-b-PSS-EMIm), with a functionally antagonistic core-shell architecture that is specifically designed as an ionic exchangeable polymer electrolyte. The corresponding actuator shows exceptionally good actuation performance, with a high displacement of 8.22 mm at an ultralow voltage of 0.5 V, a fast rise time of 5 s, and excellent durability over 14 000 cycles. It is envisaged that the development of this high-performance ionic soft actuator could contribute to the progress toward the realization of the aforementioned applications. Furthermore, the procedure described herein can also be applied for developing novel polymer electrolytes related to solid-state lithium batteries and fuel cells.

Two-Dimensional rGO-MoS2 Hybrid Additives for High-Performance Magnetorheological Fluid.

Magnetorheological fluids (MRF) that undergo a change in their viscoelastic properties under the magnetic fields have been considered as one of most important smart functional materials for vibration dampers and shock absorbers in several engineering applications. However, the use of magnetorheological fluids in practical applications has been limited by poor sedimentation ratio and on-state yield stress. Herein, we report hybrid rGO-MoS2 additives for a high-performance magnetorheological fluid. Two different kinds of hybrid additives, which are called non-magnetic rGO-MoS2 and magnetic Fe-rGO-MoS2, were synthesized by using a hydrothermal method. The rGO-MoS2 added suspensions remained stable for the first 90 min whereas the CIP MRFs settled down quickly (65%) in the first 10 minutes. The Fe-rGO-MoS2 additives showed a 24% higher on-state shear stress as compared to CIP MRFs. On the other hand, an increase of 60% in the on-state yield stress for Fe-rGO-MoS2 MRF can be attributed to the gap-filling by the hybrid additives during columnar-structure formation. Among two-dimensional (2D) materials, Molybdenum Disulphide (MoS2) is a member of transition metal dichalcogenides (TMDCs), traditionally used as solid lubricant, while reduced graphene-oxide (rGO) is a well-known 2D material with supreme mechanical properties. We believe that this study will blaze the new way for developing a high-performance magnetorheological fluids based on various 2D material hybrids.