High-Performance PEDOT:PSS/Hexamethylene Diisocyanate-Functionalized Graphene Oxide Nanocomposites: Preparation and Properties.

José Luceño Sánchez,Rafael Peña Capilla,Ana Díez-Pascual

doi:10.3390/polym10101169

Abstract

Graphene oxide (GO) has emerged as an ideal filler to reinforce polymeric matrices owing to its large specific surface area, transparency, flexibility, and very high mechanical strength. Nonetheless, functionalization is required to improve its solubility in common solvents and expand its practical uses. In this work, hexamethylene diisocyanate (HDI)-functionalized GO (HDI-GO) has been used as filler of a conductive polymer matrix, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The nanocomposites have been prepared via a simple solution casting method, and have been characterized by scanning electron microscopy (SEM), UV–Vis and Raman spectroscopies, X-ray diffraction (XRD), thermogravimetric analysis (TGA), tensile tests, and four-point probe measurements to get information about how the HDI-GO functionalization degree (FD) and the HDI-GO concentration in the nanocomposite influence the final properties. SEM analysis showed a very homogenous dispersion of the HDI-GO nanosheets with the highest FD within the matrix, and the Raman spectra revealed the existence of very strong HDI-GO-PEDOT:PSS interactions. A gradual improvement in thermal stability was found with increasing HDI-GO concentration, with only a small loss in transparency. A reduction in the sheet resistance of PEDOT:PSS was found at low HDI-GO contents, whilst increasing moderately at the highest loading tested. The nanocomposites showed a good combination of stiffness, strength, ductility, and toughness. The optimum balance of properties was attained for samples incorporating 2 and 5 wt % HDI-GO with the highest FD. These solution-processed nanocomposites show considerably improved performance compared to conventional PEDOT:PSS nanocomposites filled with raw GO, and are highly suitable for applications in various fields, including flexible electronics, thermoelectric devices, and solar energy applications.

Highlights

Conductive films comprising conductive polymers [1], carbon-based nanomaterials [2], and hybrid nanocomposites [3] have attracted a lot of interest for applications in several fields, including transparent electrodes, supercapacitors, light-emitting diodes (LEDs), solar cells, thermoelectric devices, and so forth [3,4,5,6]
Similar morphology was found for hexamethylene diisocyanate (HDI)-Graphene oxide (GO) 1, albeit with thinner sheets, corroborating that the flake thickness increases with increasing functionalization degree (FD)
thermogravimetric analysis (TGA) results demonstrate that the addition of Hexamethylene Diisocyanate-Functionalized Graphene Oxide (HDI-GO) with a high FD significantly improves the thermal stability of PEDOT:PSS, which is an important result from a practical viewpoint particular for the purpose of photovoltaic application

Summary

Introduction

Conductive films comprising conductive polymers [1], carbon-based nanomaterials [2], and hybrid nanocomposites [3] have attracted a lot of interest for applications in several fields, including transparent electrodes, supercapacitors, light-emitting diodes (LEDs), solar cells, thermoelectric devices, and so forth [3,4,5,6]. Conductive polymers show great potential for the aforementioned applications owing to their exceptional optical and electrical properties combined with their light weight, low cost, flexibility, and outstanding. Poly(3,4-ethylenedioxythiophene) (PEDOT), composed of ethylenedioxythiophene (EDOT) monomers, is a very promising material owing to its good electrochemical properties, inexpensiveness, and high transparency. It is insoluble in numerous common solvents and oxidizes rapidly under air. Owing to its very high conductivity, processing simplicity, and superior chemical and electrochemical stability, as well as excellent dispersibility in various solvents, PEDOT:PSS has been widely used as conductive material for flexible electronic and optoelectronic devices [8], such as sensors, hole-injection layer of organic

Methods

Results

Conclusion