In situ polymerized PEDOT dispersions with sulfated cellulose nanofibrils for 1D and 2D conductors

Abstract

Sulfated cellulose nanofibrils (SCNFs, 1.7 ± 0.7 nm high, 3.6 ± 0.9 nm wide, 880 ± 320 nm long) with 1.81 mmol g⁻¹ surface charge or ca. 84% C6 sulfation have shown to be effective co-polyelectrolytes with poly(styrene sulfonate) (PSS) in the synthesis of poly(3,4-ethylenedioxythophene) (PEDOT). Stable aqueous dispersions of PEDOT:PSS/SCNF were synthesized with up to 50 wt% PEDOT fractions in the presence of any combination of SCNF and/or PSS as co-polyelectrolytes. The closely matched spacing between the SCNF anionic groups and PEDOT cationic groups facilitated the alignment of PEDOT along the surface of nanofibrils to enhance conductivity of 2D cast films and 1D wet spun fibers to 0.14 S cm⁻¹ and 40 S cm⁻¹, respectively. Ethylene Glycol (EG) further acted on the PSS in the PEDOT:PSS/SCNF complexes to improve the conductivity of films to a maximum of 37.5 S cm⁻¹ and that of fibers to 6150 S cm⁻¹. Most impressively, wet spinning PEDOT:PSS/SCNF with 30% SCNF in the polyanions directly into 72% sulfuric acid yielded fibers with an even higher conductivity of 15 500 ± 3500 S cm⁻¹.