Electrically Conductive Bacterial Cellulose by Incorporation of Carbon Nanotubes

Abstract

Electrically conducting polymeric membranes were prepared by incorporating multiwalled carbon nanotubes (MWCNTs) into bacterial cellulose pellicles produced by Gluconacetobacter xylinum. The MWCNTs were dispersed in a surfactant (cationic cetyl trimethylammonium bromide) solution, and cellulose pellicles were dipped into the solution for 6, 12, and 24 h. The surfactants were then extracted in pure water and dried. Electron microscopy showed that the individual MWCNTs were strongly adhered to the surface and the inside of the cellulose pellicle. The conductivity of the MWCNTs-incorporated cellulose pellicle, as measured by a four-probe at room temperature, was 1.4 x 10(-1) S/cm, based on the total cross-sectional area (approximately 9.6 wt % of MWCNTs). This suggests that the MWCNTs were incorporated uniformly and densely into the pellicles.

Electrically conductive bacterial cellulose composite membranes produced by the incorporation of graphite nanoplatelets in pristine bacterial cellulose membranes

“…GNP/BC composite membrane with the maximum electrical conductivity 4.5 S/cm was found to contain 8.7 wt% GNPs, while MWCNT/ BC composite membrane with the maximum electrical conductivity 1.2 S/cm, which surpasses the maximum electrical conductivity 1.4!10 -1 S/cm of immersion-prepared BC composite membrane incorporated with 9.6 wt% MWCNTs reported by elemental analysis in Ref. [5], was found to be incorporated by 13.9 wt% MWCNTs. Therefore, compared with 1-D MWCNTs, as long as GNPs inserted into BC membranes, the 2-D reinforcement of GNPs was proven to be more effective in improving the electrical conductivity of BC membranes thus not only break the bottleneck of further improving the electrical conductivity of BC-based composite membranes but also broaden the applications of BC and GNPs.…”

“…GNPs have advantage in forming conducting pathways due to their 2-D morphology and thus supposedly allow the electrical conductivity of composite membranes to be enhanced to a greater extent than other spherical or rod-like conducting particles. An attempt was made to determine the amount of GNP or MWCNT particles incorporated in the BC membranes using Thermogravimetric Analysis under a nitrogen atmosphere, but this measurement was unsuccessful and the cause was proved to be in accord with the explanation previously reported [5], i.e. the BC membrane charred after burning up to about 600°C and did not decompose completely.…”

“…It is important to separate GNP or MWCNT bundles individually and stabilize them against van der Waals attraction before inserting into BC membranes for employing the inherent properties of individual nanomaterial as well as facilitating their insertion into the porous BC nanofibril network. A well-dispersed MWCNT suspension was previously achieved by using surfactant NaDDBS [6], and NaDDBS is demonstrated to be more desirable than CTAB as the surfactant for MWCNTs based on the fact that under identical preparation conditions, the electrical conductivity of MWCNT/BC composite membranes obtained by dipping BC membranes in the NaDDBS-stabilized MWCNT suspension is higher than that of MWCNT/ BC composite membranes obtained from CTABstabilized MWCNT suspension [5,6]. Therefore, in this work NaDDBS was used as a reference surfactant.…”

“…Therefore, in this work NaDDBS was used as a reference surfactant. Furthermore, the fabrication process of BCbased composite membranes, both GNP/BC composite membranes and MWCNT/BC composite membranes, was fundamentally similar to the process used in the previous study [5,6] except for the used surfactant and solvent, specifically, in this study A1100 was also chosen as a reference surfactant for comparison and the solvent used is volatile absolute ethanol instead of water. Generally, nanomaterials are sonicated in the solution of surfactant to facilitate their dispersion.…”

“…Carbon nanotubes (CNTs), a type of one-dimensional (1-D) carbon nanomaterials with remarkable electrical conductivity, have been utilized in improving the electrical conductivity of insulating BC membranes for use in electronics such as electrodes [5][6][7][8][9][10]. Yoon and coworkers [5,6] dipped BC membrane in a surfactant-stabilized 0.05 wt% multiwalled CNT (MWCNT) well-dispersed aqueous solution for 24 h, consequently MWCNTs were found to be inserted in the BC membrane and the electrical conductivity of MWCNT/BC composite membranes with different MWCNTs' surfactants, cationic cetyltrimethylammonium bromide (CTAB) or sodium dodecylbenzenesulfonate (NaDDBS), greatly increased to 1.4!10 -1 and 4.2!10 -1 S/cm, respectively. Jung et al [7] also utilized BC membrane as the template to deposit MWCNTs uniformly, then used silk fibroin as coating material for the MWCNT-incorporated BC membrane, the electrical conductivities of the resulting composite membranes consequently achieved respectively 5.3!10 -3 and 3.6!10 -3 S/cm from CTAB-stabilized 0.03 or 0.05 wt% MWCNT aqueous dispersion (immersion time was unaccounted).…”