Hydrophilic Poly(vinylidene Fluoride) Film with Enhanced Inner Channels for Both Water- and Ionic Liquid-Driven Ion-Exchange Polymer Metal Composite Actuators

Abstract

This study presents a novel and facile strategy to fabricate a hydrophilic poly(vinylidene fluoride) (PVDF) electrolyte film with enhanced inner channels for a highperformance and cost-effective ion-exchange polymer metal composite (IPMC) actuator. The resultant PVDF composite film is composed of hierarchical micro/nanoscale structures: well-defined polymer grains with a diameter of ∼20 μm and much finer particles with a diameter of ∼390 nm, producing three-dimensional interconnected, hierarchical inner channels to facilitate ion migration of IPMC. Interestingly, the electrolyte matrix film has a high porosity of 15.8% and yields a high water uptake of 44.2% and an ionic liquid (IL, [EMIm]•[BF 4 ]) uptake of 38.1% to make both water-driven and IL-driven IPMC actuators because of the introduction of polar polyvinyl pyrrolidone. Compared to the conventional PVDF/IL-based IPMC, both water-driven and IL-driven PVDF-based IPMCs exhibit high ion migration rates, thus effectively improving the actuation frequency and producing remarkably higher levels of actuation force and displacement. Specifically, the force outputs are increased by 13.4 and 3.0 folds, and the displacement outputs are increased by 2.2 and 1.9 folds. Using an identical electrolyte matrix, water-driven IPMC exhibits stronger electromechanical performance, benefiting to make IPMC actuator with high levels of force and power outputs, whereas IL-driven IPMC exhibits a more stable electromechanical performance, benefiting to make long lifetime IPMC actuator in air. Thus, the resultant IPMCs are promising in the design of artificial muscles with tunable electromechanical performance for flexible actuators or displacement/vibration sensors at low cost. KEYWORDS: ionic exchange polymer metal composite (IPMC), electromechanical response, poly(vinylidene fluoride) (PVDF), polyvinyl pyrrolidone (PVP), ionic liquid (IL), inner channel

Materials as Machines

“…Other work has focused on improving IPMCs by diversifying their electrolyte film chemistries. Recently, a polyvinyl pyrrolidone‐modified PVDF composition was reported by Guo et al that incorporates ionic liquids (ILs) to prepare bending cantilevers capable of 75° deformation in response to less than 10 V 227. Other reports document the use of imidazolium cations, among others, and anions such as trifluoromethane sulfonate (TfO) to prepare PVDF‐based IPMCs 214,228–232.…”

Sulfonic SiO2 nanocolloid doped perfluorosulfonic acid films with enhanced water uptake and inner channel for IPMC actuators

“…Introduction of functionalized SiO 2 nanocolloids signicantly changes the matrix lm's polarity, WU, IEC, and mechanical property, thus affecting IPMC's electromechanical performance. [31][32][33][34][35]41 The detected water CAs are 84.1, 75.7, and 54.5 for the pure PFSA, SH-SiO 2 /PFSA, and HSO 3 -SiO 2 /PFSA lms, respectively ( Fig. 5a and Table 2), thus both hybrid lms become more hydrophilic due to additions of SiO 2 nanocolloids, whose surfaces widely distribute hydrophilic Si-OH and Si-O-Si groups.…”

Facile way of dynamically tailoring microporous structures in polyvinylidene fluoride films prepared by thermally induced phase separation

“…), which make it widely applied in membrane distillation, membrane contactor as well as wastewater treatment 1–3 . Till now, great efforts have been made on fabrication of PVDF films with desirable performance 4–8 …”

“…made on fabrication of PVDF films with desirable performance. [4][5][6][7][8] The primary methods of preparing PVDF films include sintering, melt spinning stretching, non-diluent phase separation (NIPS) and thermally-induced phase separation (TIPS), 1,[9][10][11][12] among which TIPS proposed by Castro in 1981 has proved to be applicable for a wide range of polymers (amorphous or crystalline). 13 During a typical TIPS process, a homogeneous solution was prepared by mixing polymer with diluent of a high boiling point at elevated temperature, followed by a TIPS process by quenching the solution.…”