Highly conductive paper fabricated with multiwalled carbon nanotubes and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) by unidirectional drying

Poly(3, 4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) was used to directly disperse multiwalled carbon nanotubes (MWNTs) into a stable solution without the aid of any other surfactants. The solution was coated onto paper substrates and was subsequently dried via two different methods: conventional multidirectional drying and a special unidirectional drying method with the aid of a ceramic heating board. The samples that were dried using the unidirectional drying method had a lower resistance than when dried with the conventional drying method, which allowed it to have a better conductivity. For solutions containing 1–4 mg/mL MWNTs, which were dispersed with 1 mg/mL PEDOT:PSS, the measured conductivity ranged from 21 ± 0.5 to 46 ± 10 S/cm. These values are one to three orders of magnitude higher than those obtained for MWNT films often reported in the literature as well as for films we fabricated using MWNTs dispersed with SDBS, or PEDOT:PSS solution by itself. AFM and SEM images showed that the surface of MWNTs films made with PEDOT:PSS as a surfactant was very smooth and the layers tended to be thinner than when made with the other surfactants. It was demonstrated using FTIR analysis that the MWNTs become part of the 3D structure of the paper substrate material because chemical bonding between the PEDOT:PSS, the MWNTs and the paper fibers occurred during the drying stage.