A Combined XRD, Solvatochromic, and Cyclic Voltammetric Study of Poly (3,4-Ethylenedioxythiophene) Doped with Sulfonated Polyarylethersulfones: Towards New Conducting Polymers.

Valentina Sabatini,Marco Aldo Ortenzi,Stefano Checchia,Valentina Pifferi,Hermes Farina,Sara Rebeccani,Luigi Falciola

doi:10.3390/polym10070770

Abstract

Despite the poor solubility in organic solvents, poly (3,4-ethylenedioxythiophene) (PEDOT) is one of the most successful conducting polymers. To improve PEDOT conductivity, the dopants commonly used are molecules/polymers carrying sulfonic functionalities. In addition to these species, sulfonated polyarylethersulfone (SPAES), obtained via homogeneous synthesis with different degrees of sulfonation (DS), can be used thanks to both the tight control over the DS and the charge separation present in SPAES structure. Here, PEDOTs having enhanced solubility in the chosen reaction solvents (N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone) were synthesized via a high-concentration solvent-based emulsion polymerization with very low amounts of SPAES as dopant (1% w/w with respect to EDOT monomer), characterized by different DS. The influence of solvents and of the adopted doping agent was studied on PEDOT_SPAESs analyzing (i) the chemical structure, comparing via X-ray diffraction (XRD) the crystalline structures of undoped and commercial PEDOTs with PEDOT_SPAES’ amorphous structure; (ii) solvatochromic behavior, observing UV absorption wavelength variation as solvents and SPAES’ DS change; and (iii) electrochemical properties: voltammetric peak heights of PEDOT_SPAES cast onto glassy carbon electrodes differ for each solvent and in general are better than the ones obtained for neat SPAES, PEDOTs, and glassy carbon.

Highlights

In recent years, the fabrication of conductive electrodes based on conductive polymer composites (CPCs) has gained an increasing academic and industrial research interest
The present study aims to fill this technological gap by reporting, for the first time, the preparation of electrodes based on highly conductive and processable PEDOT coatings
PEDOT_Naphs contain inorganic solvents, PEDOTs characterized by a full miscibility in the reaction solvents used were significantly more sulfonic groups

Summary

Introduction

The fabrication of conductive electrodes based on conductive polymer composites (CPCs) has gained an increasing academic and industrial research interest. Even if different silver and titanium coatings have been formulated and tested, the high cost and the low metal content limit their widespread industrial applications [8]. Many research groups have fabricated conductive electrodes using different carbon-based fillers, such as carbon nanotubes (CNT) [9], graphene (G) [10] and graphene oxide (GO) [11]. Though all these materials offer excellent conductive properties, the raw materials are expensive and not modifiable in order to improve the conductive features of the final devices [12]. There is a need to develop new types of conductive electrodes able to overcome the technical problems previously reported for metals and carbon-based coatings and, there are pressing needs to develop large-scale, low-cost fabrication routes of high-performance conductive electrodes

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Conclusion