Nanowires with Conductivities Comparable to Their Bulk Films from an Electrospun Self-Doped Water-Soluble Conductive Polymer

Electrospinning of conducting polymer blends, such as PEDOT:PSS, on a flexible substrate such as PDMS has been a practical approach to obtaining stretchable substrates that are conductive. However, the intrinsic conductivity of the doped polymer is often not preserved when it is electrospun as nanofibers. Knowing the PSS dopant leads to insulating domains in the nanofibers, this study aimed to eliminate this conductivity-limiting external dopant. A fully water-soluble, self-doped conductive polymer (p(PDS)), not requiring an external dopant, served to prepare nanofibers by electrospinning. This was to replace PEDOT:PSS in electrospinning nanofibers, whose conductivity could be on par with its corresponding bulk conductivity in thin films. Toward this goal, the effects of carrier polymer content, organic cosolvent, and pH on both the morphology and conductivity of the nanofibers were assessed. The sheet resistance of nanofibers electrospun from p(PDS) on PDMS tape improved >100-fold (4.5 × 104 Ω/sq) by adjusting the electrospinning solution to pH < 2 along with adding DMF as a cosolvent. Postelectrospinning dopant exchange treatment was not required for this improvement. The nanofibers electrospun on an elastomeric tape maintained a threshold conductivity when stretching the substrate, upward of 100%. Also, the original sheet resistance was restored upon releasing the applied stress/strain. The effects of electrospinning solution composition on the morphology of the conductive nanofibers provide key knowledge that can be used for preparing conductive stretchable substrates that potentially meet the mechanical and electrical requirements for their use in wearable electronics.