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

Abstract

Conducting polymers like polyaniline (PANI) have gained a lot of interest due to their outstanding electrical and optoelectronic properties combined with their low cost and easy synthesis. To further exploit the performance of PANI, carbon-based nanomaterials like graphene, graphene oxide (GO) and their derivatives can be incorporated in a PANI matrix. In this study, hexamethylene diisocyanate-modified GO (HDI-GO) nanosheets with two different functionalization degrees have been used as nanofillers to develop high-performance PANI/HDI-GO nanocomposites via in situ polymerization of aniline in the presence of HDI-GO followed by ultrasonication and solution casting. The influence of the HDI-GO concentration and functionalization degree on the nanocomposite properties has been examined by scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), tensile tests, zeta potential and four-point probe measurements. SEM analysis demonstrated a homogenous dispersion of the HDI-GO nanosheets that were coated by the matrix particles during the in situ polymerization. Raman spectra revealed the existence of very strong PANI-HDI-GO interactions via π-π stacking, H-bonding, and hydrophobic and electrostatic charge-transfer complexes. A steady enhancement in thermal stability and electrical conductivity was found with increasing nanofiller concentration, the improvements being higher with increasing HDI-GO functionalization level. The nanocomposites showed a very good combination of rigidity, strength, ductility and toughness, and the best equilibrium of properties was attained at 5 wt % HDI-GO. The method developed herein opens up a versatile route to prepare multifunctional graphene-based nanocomposites with conductive polymers for a broad range of applications including flexible electronics and organic solar cells.

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

“…As known, raw graphite shows an intense diffraction peak at 2θ = 26.5 • , which corresponds to a d value of 0.336 nm taking into account the Bragg's equation. This peak was not observed in any of the synthesized EGOs, since it disappeared after oxidation, while a new peak appeared in the range of 9-12 • corresponding to the (001) reflection of GO [53]. The presence of this characteristic peak corroborates that all the samples were partially or completely oxidized during the electrochemical process.…”

Selected Papers from the 1st International Online Conference on Nanomaterials

“…Besides, it was found that the covalent bonding of HDI enhances the thermal stability of GO due to chemical crosslinking between neighboring sheets, which is advantageous for long-term electronics and electrothermal device applications. These HDI-GO samples are perfect candidates as nanofillers for the development of high-performance GO-based polymeric nanocomposites [13,14].…”

Grafting of Polypyrrole-3-carboxylic Acid to the Surface of Hexamethylene Diisocyanate-Functionalized Graphene Oxide

“…Pyrrole-3-carboxylic acid (C 5 H 5 NO 2 > 97%, M w = 111.1 g/mol, d 25°C = 0.862 g/cm 3 ), ammonium persulfate ((NH 4 ) 2 S 2 O 8 , 98%, M w = 228.20 g/mol, d 25°C = 1.98 g/cm 3 ), dimethylformamide (DMF, 99% C 3 H 7 NO, M w = 73.09 g/mol, d 25°C = 0.944 g/cm 3 ), N,N-dicyclohexylcarbodiimide (DCC, 99%, C 13 H 22 N 2 , M w = 206.33 g/mol; d 25°C = 1.32 g/cm 3 ), 4-dimethylaminopyrydine (DMAP, 99%, C 7 H 10 N 2 , M w = 122.17 g/mol, d 25°C = 0.96 g/cm 3 ), and thionyl chloride (SOCl 2 , 97%, M w = 118.96 g/mol, d 25°C = 1.64 g/cm 3 ) were obtained from Sigma-Aldrich (Madrid, Spain). Hexamethylene diisocyanate-modified graphene oxide (HDI-GO), with a functionalization degree of 18.1%, was synthesized according to our previous works [22,23]. The organic solvents (HPLC grade) were obtained from Scharlau S.L.…”