Fabrication of Cellulose Nanofiber Actuators by One-Step Adhesion of the Conducting Fabric Electrodes

Abstract

Long cellulose nanofibers and shorter rod-shaped cellulose nanocrystals are generally referred to as nanocellulose. They exhibit hierarchical structures with a width of 2‒20 nm and are included in native celluloses originating from plants. Nanofibers have been extensively investigated for various applications because of their unique structural properties, nanoscale effects, and large surface area[1, 2]. During the development of cellulose nanofibers, obtaining fine and long fibers is necessary to introduce advanced features into such natural materials. Fine cellulose nanofibers can be prepared by the mechanical disintegration of natural fibers after appropriate pretreatments. Cellulose nanofibers can be prepared using various methods, including enzymatic[3], mechanochemical[4], oxidation[5, 6], or esterification[7]. 2,2,6,6 tetramethyl piperidinyl 1 oxyl radical (TEMPO) is a stable radical that mediates the oxidation from primary alcohols to the carboxylic acid groups. Cellulose nanofibers can be obtained by defibrating the cellulose fiber aggregates using TEMPO[8, 9]. During cellulose defibration by oxidation with TEMPO at room temperature when the pH is approximately 10, the C6 primary hydroxyls of nanocellulose are selectively converted to the C6 carboxylate groups[10]. Therefore, TEMPO-mediated oxidation is the key to disperse the nanofiber surfaces of the cellulose and polyelectrolyte structures of the carboxylate groups[11, 12]. Conducting fabrics are attractive fiber-based materials that can be used to suppress the electromagnetic interference from electronic devices [13‒16]. Compared with conventional metal-based mesh materials, conducting fabrics are more flexible and lightweight[13‒16]. Polymer actuators have recently attracted considerable attention owing to their unique features and the possibility of them being used to develop mechanical energy transducers for producing direct bending and stretching motions as an alternative technology to electric motors[17‒19]. For example, the ionic polymer metal composites (IPMCs) have exhibited an excellent performance, providing large bending displacements at applied potentials of only a few volts[20‒22]. An electroless plating method was used to introduce electrodes onto both sides of a polyelectrolyte film. Instead of using electroless plating methods, polymer actuators can be fabricated 【SPECIAL EDITIONS on Annual Meeting-Rapid Communication】