由分子链构象转变及结构重组引起的聚3,4-乙烯二氧噻吩-聚苯乙烯磺酸/聚乙烯醇纤维高性能化

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

采用一种新颖的二甲基亚砜(DMSO)蒸汽处理的方法制备高导电性的(聚3,4-乙烯二氧噻吩-聚苯乙烯磺酸盐/聚乙烯醇)(PEDOT:PSS/PVA)有机导电纤维.通过分析蒸汽处理前后纤维在化学结构、形貌、表面化学组分及分子链构象等方面的变化,探究蒸汽处理提高纤维导电性能的机理.结果表明,蒸汽处理引起纤维内部结构重组和分子链构象转变,显著提高了纤维导电性能.蒸汽处理使PEDOT和PSS间发生相分离,部分无定形的PSS链段富集到纤维表面,减少了毗邻的导电PEDOT颗粒间绝缘的PSS层厚度,促使导电PEDOT颗粒之间形成更好的导电网络通路,进而增强纤维导电性能.蒸汽热处理还使PEDOT分子链构象由苯式结构转变为利于载流子传输的醌式结构.随着蒸汽处理的进行,纤维表面变得光滑,表面粗糙度下降;同时,纤维的力学性能有所提升.

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-l 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.