Nanowires with Conductivities\nComparable to Their\nBulk Films from an Electrospun Self-Doped Water-Soluble Conductive\nPolymer

Electrospinning of conducting polymer blends, such as\nPEDOT:PSS,\non a flexible substrate such as PDMS has been a practical approach\nto obtaining stretchable substrates that are conductive. However,\nthe intrinsic conductivity of the doped polymer is often not preserved\nwhen it is electrospun as nanofibers. Knowing the PSS dopant leads\nto insulating domains in the nanofibers, this study aimed to eliminate\nthis conductivity-limiting external dopant. A fully water-soluble,\nself-doped conductive polymer (<b>p(PDS)</b>), not requiring\nan external dopant, served to prepare nanofibers by electrospinning.\nThis was to replace PEDOT:PSS in electrospinning nanofibers, whose\nconductivity could be on par with its corresponding bulk conductivity\nin thin films. Toward this goal, the effects of carrier polymer content,\norganic cosolvent, and pH on both the morphology and conductivity\nof the nanofibers were assessed. The sheet resistance of nanofibers\nelectrospun from <b>p(PDS)</b> on PDMS tape improved >100-fold\n(4.5 × 10<sup>4</sup> Ω/sq) by adjusting the electrospinning\nsolution to pH < 2 along with adding DMF as a cosolvent. Postelectrospinning\ndopant exchange treatment was not required for this improvement. The\nnanofibers electrospun on an elastomeric tape maintained a threshold\nconductivity when stretching the substrate, upward of 100%. Also,\nthe original sheet resistance was restored upon releasing the applied\nstress/strain. The effects of electrospinning solution composition\non the morphology of the conductive nanofibers provide key knowledge\nthat can be used for preparing conductive stretchable substrates that\npotentially meet the mechanical and electrical requirements for their\nuse in wearable electronics.