Research in smart textiles is growing due to the increased demand from the healthcare sector and people's urge to keep track of and analyze the signals and metrics from their bodies. Electrically conductive filaments are the most fundamental material for smart textiles. These filaments can be imbued with functionalities and useful in fields like energy storage, sensing, and actuation. To be able to meet the requirements that the latter applications require, fabrication techniques must be developed to provide better processability and sustainability in a cost-effective manner. Here, a mixture of a conductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), and biobased cellulose nanofibrils (CNFs) was used to spin filaments utilizing a water-based process. These filaments show electrical conductivities up to 150 S/cm and tensile stiffness of 20 GPa. Interestingly, the PEDOT aligned to a similar degree as the CNFs during the spinning process without a drawing step, which is hypothesized to be caused by the attachment of PEDOT on the CNFs. Lastly, the filaments were tested in an organic electrochemical transistor (OECT) configuration, which resulted in a working device with an on/off ratio approaching 1500. Furthermore, the OECT exhibited stable behavior when changing temperature (20-80 °C) and relative humidity (40-80%). This aqueous spinning method, resulting in filaments with robust electronic properties in different temperature and humidity environments, show greats promise for future innovative smart textiles. 

This study presents a novel, green, and efficient way of preparing crosslinked aerogels from cellulose nanofibers (CNFs) and alginate using non-covalent chemistry. This new process can ultimately facilitate the fast, continuous, and large-scale production of porous, light-weight materials as it does not require freeze-drying, supercritical CO2 drying, or any environmentally harmful crosslinking chemistries. The reported preparation procedure relies solely on the successive freezing, solvent-exchange, and ambient drying of composite CNF-alginate gels. The presented findings suggest that a highly-porous structure can be preserved throughout the process by simply controlling the ionic strength of the gel. Aerogels with tunable densities (23-38 kg m(-3)) and compressive moduli (97-275 kPa) can be prepared by using different CNF concentrations. These low-density networks have a unique combination of formability (using molding or 3D-printing) and wet-stability (when ion exchanged to calcium ions). To demonstrate their use in advanced wet applications, the printed aerogels are functionalized with very high loadings of conducting poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:TOS) polymer by using a novel in situ polymerization approach. In-depth material characterization reveals that these aerogels have the potential to be used in not only energy storage applications (specific capacitance of 78 F g(-1)), but also as mechanical-strain and humidity sensors.

Composites of biopolymers and conducting polymers are emerging as promising candidates for a green technological future and are actively being explored in various applications, such as in energy storage, bioelectronics, and thermoelectrics. While the device characteristics of these composites have been actively investigated, there is limited knowledge concerning the fundamental intracomponent interactions and the modes of molecular structuring. Here, by use of cellulose and poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), it is shown that the chemical and structural makeup of the surfaces of the composite components are critical factors that determine the materials organization at relevant dimensions. AFM, TEM, and GIVVAXS measurements show that when mixed with cellulose nanofibrils, PEDOT:PSS organizes into continuous nanosized beadlike structures with an average diameter of 13 nm on the nanofibrils. In contrast, when PEDOT:PSS is blended with molecular cellulose, a phase-segregated conducting network morphology is reached, with a distinctly relatively lower electric conductivity. These results provide insight into the mechanisms of PEDOT:PSS crystallization and may have significant implications for the design of conducting biopolymer composites for a vast array of applications.

Paper is emerging as a promising flexible, high surface-area substrate for various new applications such as printed electronics, energy storage, and paper-based diagnostics. Many applications, however, require paper that reaches metallic conductivity levels, ideally at low cost. Here, an aqueous electroless copper-plating method is presented, which forms a conducting thin film of fused copper nanoparticles on the surface of the cellulose fibers. This paper can be used as a current collector for anodes of lithium-ion batteries. Owing to the porous structure and the large surface area of cellulose fibers, the copper-plated paper-based half-cell of the lithium-ion battery exhibits excellent rate performance and cycling stability, and even outperforms commercially available planar copper foil-based anode at ultra-high charge/discharge rates of 100 C and 200 C. This mechanically robust metallic-paper composite has promising applications as the current collector for light-weight, flexible, and foldable paper-based 3D Li-ion battery anodes.

In this work, we report macroscopic electromagnetic devices made from conducting polymers. We compare their fundamental properties and device parameters with those of similar devices made from copper wires. By using self-standing supra-ampere conducting polymer wires, we are able to manufacture inductors that generate magnetic fields well over 1 G, and incorporate them in feedback LC oscillators operating at 8.65 MHz. Moreover, by utilizing the unique electrochemical functionality of conducting polymers, we demonstrate electrochemically-tunable electromagnets and electromagnetic chemical sensors. Our findings pave the way to lightweight electromagnetic technologies that can be processed (fromwater dispersions) using low-temperature protocols into flexible shapes and geometries.