Conductive Cellulose based Foam Formed 3D Shapes—From Innovation to Designed Prototype

Abstract

In this article, we introduce for the first time, a method to manufacture cellulose based electrically conductive non-woven three-dimensional (3D) structures using the foam forming technology. The manufacturing is carried out using a minimum amount of processing steps, materials, and hazardous chemicals. The optimized solution applies a single surfactant type and a single predefined portion for the two main processing steps: (1) the dispersing of nanocellulose (NC) and carbon nanotubes (CNT) and (2) the foam forming process. The final material system has a concentration of the used surfactant that is not only sufficient to form a stable and homogeneous nanoparticle dispersion, but it also results in stable foam in foam forming. In this way, the advantages of the foam forming process can be maximized for this application. The cellulose based composite material has a highly even distribution of CNTs over the NC network, resulting a conductivity level of 7.7 S/m, which increased to the value 8.0 S/m after surfactant removal by acetone washing. Also, the applicability and a design product case ‘Salmiakki’ were studied where the advantages of the material system were validated for a heating element application.

Cellulose-Multiwall Carbon Nanotube Fiber Actuator Behavior in Aqueous and Organic Electrolyte

“…A number of applications for cellulose composites have been proposed, such as supercapacitors [ 11 ], electrode material for Li-batteries [ 12 ] and multifunctional materials [ 13 ]. Cellulose-based composites with carbon nanotubes [ 14 , 15 , 16 ], reduced graphene oxide [ 17 ], conducting polymers [ 18 ] and others have come in focus for environmentally sustainable solutions, providing opportunities to form materials with usable electrical conductivity and switchable electrical and optical properties due to the wide range of morphological forms of cellulose [ 19 ].…”

Foam forming of fiber products: a review

“…Moreover, it is also possible to get tailored properties such as antibacterial properties [147] in medical or hygienic applications, [148,149] designed microstructures, [21] or conductive cellulose-based structures. [150] Possible other high-tech applications include soft composites, [151] sensors, [152] chromatography and other diagnostics, substrates for biocatalytic and chemical conversion, and fiber materials with imbedded optics and electronics. In Table 2, we summarize the main potential application areas for foam forming and the characteristic features of each of them.…”

Applications of Nanocellulose/Nanocarbon Composites: Focus on Biotechnology and Medicine

“…Other ways include the functionalization of CNTs with self-assembling amphiphilic glycosylated proteins [142] or the use of oil-in-water Pickering emulsions of cellulose nanoparticles [143]. From the aqueous dispersions, 2D and 3D nanocellulose/CNT composites can be formed, e.g., by vacuum filtration, centrifugal cast molding, foam forming, casting and printing [39,45,50,141]. Pickering emulsions of cellulose nanocrystals and SWCNTs or MWCNTs were used for fabricating aerogels and foams by freeze-drying [143].…”

“…Energy-related applications of nanocellulose/CNT composites include biofuel cells, varactors, supercapacitors, and electrodes for lithium batteries, thermoelectric generators for heat-to-electricity conversion or for constructing heating elements [50]. A biofuel cell comprising electrodes based on supercapacitive materials, i.e., on CNTs and a nanocellulose/polypyrrole composite, was utilized to power an oxygen biosensor.…”

“…Thermoelectric generators for heat-to-electricity conversion were based on large-area bacterial nanocellulose films with an embedded/dispersed CNT percolation network, incorporated into the films during nanocellulose production by bacteria in culture [57]. Electrical energy can also be converted into thermal energy, as demonstrated by the composite structure of wood-derived nanocellulose, MWCNTs and pulp, designed for a heating element application [50].…”