High Performance in Poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate)/Poly(vinyl alcohol) Fiber Induced by Conformational Change and Structural Rearrangement of Molecular Chains

We demonstrated a novel vapor annealing method to prepare PEDOT:PSS/PVA organic conducting fiber with high electrical conductivity and high performance. PEDOT:PSS/PVA blend fiber was prepared via wet-spinning technique from homogeneous spinning formulation composed of PVA aqueous solution and PEDOT:PSS aqueous dispersions. After that, blend fibers were annealed by dimethyl sulfoxide (DMSO) vapor to improve electrical conductivity of the blend fiber. The electrical conductivity and tensile property of the blend fiber, before and after DMSO vapor annealing, were characterized to investigate the influence of vapor annealing on their structure and property. The mechanism of performance improvement was investigated in detail by analyzing their chemical structure, surface composition, chain conformation, and surface morphology. Results showed that DMSO vapor annealing induced significant structural rearrangement in blend fibers, thereby leading to improvement in the electrical conductivity. Blend fiber reached peak conductivity of 16.5 S cm(-1) with the annealing time of 30 min. Vapor annealing induced phase separation between PEDOT grain and PSS segments, leading to amorphous PSS segments enriched on the surface of blend fibers, thus reducing the thickness of insulating PSS layer between adjacent PEDOT grains. Thinner PSS layer facilitated better connection between conductive PEDOT grains, which finally enhanced the conductivity of blend fibers. Vapor annealing also induced conformational transformation of PEDOT chains from benzoid structure to quinoid structure, which was favorable for charge transportation. As annealing time increased, fiber surface became smooth and surface roughness decreased. Meanwhile, tensile property of the blend fibers was also improved, with the Young's modulus increasing from 3.0 GPa to 3.9 GPa, and the tensile strength from 110 MPa to 144 MPa. With this approach, it is possible to scale up the production to industrial scale due to the reduction of manufacturing cost. The treated PEDOT:PSS/PVA organic conducting fibers have potential wide applications such as smart electronic components in multifunctional electronic fabrics.