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

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.

The Effect of Hexamethylene Diisocyanate-Modified Graphene Oxide as a Nanofiller Material on the Properties of Conductive Polyaniline

“…However, the reference PANI/GO sample (blue star in the plot) showed similar sheet resistance to that of PANI. Taking into account that the HDI-GO samples display higher R s than neat PANI [19], the reduction in sheet resistance found in PANI/HDI-GO nanocomposites is a surprising behavior that could be explained considering the different factors that influence the charge hopping conduction mechanism in this type of conductive polymer, including grain size, level of crystallinity, doping and screening effects as well as conformational changes of the polymeric chains [38].…”

“…HDI-GO was prepared according to the procedure described in our preceding works [18,19]. In short, firstly GO was synthesized using a modified Hummers´ method from flake graphite using H 2 SO 4 , K 2 S 2 O 8 , P 2 O 5 and KMnO 4 as oxidants.…”

Tailorable Synthesis of Highly Oxidized Graphene Oxides via an Environmentally-Friendly Electrochemical Process

“…The spectrum of the reference GO ( Figure 4) shows a broad peak centred at~3735 cm −1 assigned to the O-H stretching vibration, another at~1740 cm −1 characteristic of the C=O stretching of the COOH moieties [42], one at around 1630 cm −1 corresponding to the C=C stretching of aromatic rings, the other at about 1400 cm −1 that matches with the O-H bending vibration and bands at around 1270, and 1050 cm −1 associated with the C-O stretching in epoxy groups [43]. All these features are also present in the EGOs, which suggests that they have the same oxygen-containing functional groups as the reference GO.…”

Recent Advances in Organic Thermoelectric Materials: Principle Mechanisms and Emerging Carbon-Based Green Energy Materials

“…However, their applications are limited owing to various disadvantages, such as their high cost, relatively heavy weight, strong toxicity, and processing difficulty. Conversely, organic polymer-based thermoelectric materials are promising as a new generation of thermoelectric candidates, owing to their unique merits, such as light weight, mechanical flexibility, non-toxicity, easy processing, and inherently low thermal conductivity [29,30,31,32,33,34,35]. In the early days of their development, these organic thermoelectric materials did not have any practical significance owing to their small thermoelectric effect.…”