Bacterial cellulose in electrochemical films Nanotechnology in Forest Biomaterials 8.3.2016 Sakari Modig

Bacterial cellulose and electrochemistry Manufacturing Very pure cellulose produced by bacteria. Cellulose is further functionalized to be conductive. Protonic conductivity or electron conductivity. Fuel cells, batteries, sensors, supercapacitors, flexible circuits, etc. Different treatments With or without carbonization (pyrolysis) of BC. Surface polymerizations (e.g. PANI, PPy, PEDOT, PSS). Doping (e.g. NH3, urea, carbon nanotubes). Combinations (e.g. PANI + CNT). Short presentations of 5 different surface polymerizations.

BC with PSS and PEGDA cross-linking In situ free radical polymerization of sodium styrene sulphonate and poly(polyethylene glycol) diacrylate. BC template in polymerization reaction. No carbonization. Protonic conductivity (fuel cells, batteries) Gadim et al., Nanostructured bacterial cellulose-poly(4-styrene sulfonic acid) composite membranes with high storage modulus and protonic conductivity, ACS Appl. Mater. Interfaces, 6 (2014) pp 7864-7875.

Carbonized BC with PANI and MnO2 In situ polymerization of aniline with freeze-dried BC. Further carbonized and activated in high temperatures. MnO2 coating by doping in KMnO4. Capacitor with high energy density and 95% effiency after 5000 cycles. Long et al., Nitrogen-doped carbon networks for high energy density supercapacitors derived from polyaniline coated bacterial cellulose, Adv. Func. Mater., 24 (2014) pp 3953-3961.

BC with polypyrrole coating In situ oxidative polymerization of pyrrole with BC. Polymerization in two-phase suspension. Very high electrical conductivity. Very high mass specific capacitance. Promising for supercapacitors. Wang et al., Core-sheath structured bacterial cellulose/polypyrrole nanocomposites with excellent conductivity as supercapacitors, J. Mater. Chem. A., 1 (2013) pp 578-584.

BC with PEDOT/PSS coating BC was submerged in PSS solution, which was followed by freeze-drying. EDOT was polymerized in situ with the BC/PSS gel. Composite showed good conductivity and, furthermore, biocompatibility. Applications in electrically stimulated drug release devices, implantable biosensors and neuronal prostheses. Also capacitors… Chen et al., Facile approach to the fabrication of 3D electroconductive nanofibers with controlled size and conductivity templated by bacterial cellulose, Cellulose, 22 (2015) pp 3929-3939.

BC coated with carbon nanotubes and PANI BC was deposited onto a filter, which was then treated with carbon nanotube ink. After vaccuum filtering, aniline was deposited on top of the BC/CNT with electrochemical polymerization (0.8 V). 99.5% capacitance after 1000 cycles. Li et al., Flexible supercapacitors based on bacterial cellulose paper electrodes, Adv. Energy Mat., 4 (2014).

Conclusion Bacterial cellulose provides rigidity, chemical resistance, high surface area, and easily-modifiable template for electrochemical films and membranes. Treatments can vary from in situ polymerizations to just filtering layers onto BC. BC provides also an biocompible template in addition to classical capacitors and conductors.