High-performance TEMPO-oxidised cellulose nanofibre/PEDOT:PSS/ionic liquid gel actuators

Abstract

In a previous study that the authors have conducted, actuators based on cellulose nanofibre/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate)/ionic liquid (CNF/PEDOT:PSS/IL) gel electrodes and CNF/IL gel electrolytes could not be fabricated due to poor adhesion between the electrode and electrolyte layers. However, in this study, a series of novel actuators were developed using a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidised cellulose nanofibre (TOCN)/PEDOT:PSS/IL gel electrode with a TOCN/IL or poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF(HFP)/IL) gel electrolyte due to good adhesion between the electrode and electrolyte layers. The TOCN/PEDOT:PSS/IL gel electrode actuators exhibited high strain performance. These actuators mainly operated via an electrostatic double-layer capacitor mechanism, with a redox capacitor mechanism making a relatively small contribution. The TOCN/PEDOT:PSS/IL gel electrode actuators showed frequency-dependent displacement responses, and a model of double-layer charging kinetics considering the combined resistance of the gel electrode/electrolyte successfully simulated the experimental results. The development of electrodes with excellent electrical conductivity (PVdF(HFP)/IL electrolytes) and electrodes/electrolytes with excellent electrical and ionic conductivities (TOCN/IL gel electrolytes) will facilitate the optimisation of the performance of TOCN/PEDOT:PSS/IL-based polymer actuators. These flexible films will be applicable for the development of actuator materials for use in wearable and transparent electronic and energy conversion devices.