Sustainability of Multiwall Carbon Nanotube Fibers and Their Cellulose Composite

Abstract

Nowadays, the research community envisions smart materials composed of biodegradable, biocompatible, and sustainable natural polymers, such as cellulose. Most applications of cellulose electroactive materials are developed for energy storage and sensors, while only a few are reported for linear actuators. Therefore, we introduce here cellulose-multiwall carbon nanotube composite (Cell-CNT) fibers compared with pristine multiwall carbon nanotube (CNT) fibers made by dielectrophoresis (DEP) in their linear actuation in an organic electrolyte. Electrochemical measurements (cyclic voltammetry, square wave potential steps, and chronopotentiometry) were performed with electromechanical deformation (EMD) measurements. The linear actuation of Cell-CNT outperformed the main actuation at discharging, having 7.9 kPa stress and 0.062% strain, making this composite more sustainable in smart materials, textiles, or robotics. The CNT fiber depends on scan rates switching from mixed actuation to main expansion at negative charging. The CNT fiber-specific capacitance was much enhanced with 278 F g−1, and had a capacity retention of 96% after 5000 cycles, making this fiber more sustainable in energy storage than the Cell-CNT fiber. The fiber samples were characterized by scanning electron microscopy (SEM), BET (Braunauer-Emmett-Teller) measurement, energy dispersive X-ray (EDX) spectroscopy, FTIR, and Raman spectroscopy.

Cation-Selective Actuator–Sensor Response of Microcrystalline Cellulose Multi-Walled Carbon Nanotubes of Different Electrolytes Using Propylene Carbonate Solvent

“…The characterization of MC-MCNT is performed by using FTIR and Raman spectroscopy. BET (Braunauer-Emmett-Teller) measurements of MC-MCNT fiber have been made in recent research [25], revealing a BET-specific surface area of 101.62 m 2 g −1 , comparable to previous research [26] where 70 wt.% MCNTs were used. The average pore size distribution of MC-MCNT was 7.6 nm [25].…”

“…The charge densities have only minor differences, with TBATF having 58.8 ± 4.3 mC cm −2 , followed by EDMITF with 56.1 ± 4.1 mC cm −2 , and the lowest being found for LiTF with 50.2 ± 3.6 mC cm −2 . As shown in previous research [11,14,25] using Cell-CNT fiber, the applied electrolytes, the potential ranges, and the solvent play a role in the actuation direction (cation or anion forming the electrical double layer). When comparing this work's potential range of 0.7 V to −0.2 V to the former's [11] potential range of 0.8 V to −0.3 V, the discharging expansion was found to be comparable if the same cation, Li + , was used.…”

“…It explained that the TF − anions incorporated in the MCNT network and cations (TBA + ) form the EDL. Recent research [25] using LiTFSI (bis(trifluoromethane)sulfonimide lithium salt) electrolyte in PC solvent showed a similar tendency of MC-MCNT element detection, with no alteration of sulfur, chloride, and fluoride found at charging/discharging. Therefore, we assume that the TF − is incorporated in the MCNTs of MC-MCNT fiber and affects the linear actuation direction, with further investigation shown in the next section.…”