Graphene-Based Impregnation into Polymeric Coating for Corrosion Resistance

Abstract

This review explores the development and application of the impregnation of graphene-based materials into polymeric coatings to enhance corrosion resistance. Derivatives of graphene, such as graphene oxide (GO) and reduced graphene oxide (rGO), have been increasingly integrated into polymer matrices to enhance polymers' mechanical, thermal, and barrier properties. Various synthesis approaches, viz., electrochemical deposition, chemical reduction, and the incorporation of functionalised graphene derivatives, have been explored for improving the dispersion and stability of graphene within polymers. These graphene-impregnated coatings have shown promising results in improving corrosion resistance by enhancing impermeability to corrosive agents and reinforcing mechanical strength under corrosive conditions. While the addition of graphene notably enhances coating performance, challenges remain in achieving uniform graphene dispersion and addressing the trade-offs between thickness and flexibility. This review highlights current advancements, limitations, and future directions, with a particular emphasis on optimising the synthesis techniques to maximise corrosion resistance while maintaining coating durability and economic feasibility.

Keywords: corrosion resistance; graphene-based nano fillers; polymer-matrix composites.

Figure 1

Schematic representation of (a) synthesis of graphene, (b) graphene and its derivatives as fillers in polymer composites.

Figure 2

(a) Graphene lattice structure. (b) The honeycomb lattice configuration of monolayer graphene, where the grey and black circles represent carbon atoms located at specific lattice sites. Each atom in sublattice A (shown in green) has three nearest neighbours in sublattice B (also shown in green) and vice versa.

Figure 3

(a) Schematic illustration of a polymer composite with impregnated graphene or its derivatives. This illustrates various widely employed preparation methods of graphene and its derivatives for polymer composites: (b) solution mixing, (c) in situ polymerisation, (d) electrochemical reaction, (e) layer-by-layer (LbL) assembly, and (f) melt blending.

Figure 4

(a) Synthesis process for PANI/graphene composites (PAGCs). (b) TEM images of PAGCs05 at a low magnification and (c) high magnification. (d) Tafel plots comparing bare steel and PANI-coated, PAGCs01-coated, PACCs05-coated, PAGCs025-coated, and PAGCs05-coated electrodes, assessed in a 3.5 wt.% NaCl solution. (e) Conceptual illustration of O₂ and H₂O molecules traversing a tortuous path through PACCs and PAGCs [11].

Figure 5

(a) TEM image of PANI, (b) TEM image of NFGO, and (c) TEM image of the PANI/NFGO composite. (d) Schematic illustration of the corrosion protection mechanism [86].

Figure 6

(a) Schematic representation of the corrosion protection mechanism for GO-coated, polymer-coated, and GO–polymer bilayer-coated Cu-Ni samples. (b) Bar chart depicting E_corr and i_corr values of the uncoated, GO-coated, polymer-coated, and GO–polymer bilayer-coated Cu-Ni samples in a 3.5% (w/v) NaCl solution after 1 h of stabilisation. (c) Corrosion rates of uncoated, GO-coated, polymer-coated, and GO–polymer bilayer-coated Cu-Ni samples in a 3.5% (w/v) NaCl solution, in mils per year [85].

Figure 7

(a) Schematic illustration of the wear improvement mechanism and (b) corrosion resistance mechanism in the G/EP composite powder coating. (c) Potentiodynamic polarisation curves of the neat EP and G/EP composite coatings [87].

Figure 8

(a) Impedance dependence of neat EP/Zn, GO/EP/Zn, and PGO/EP/Zn coatings over immersion time in a 3.5 wt.% NaCl solution. (b) Tafel curves of neat EP/Zn, GO/EP/Zn, and PGO/EP/Zn samples after 300 h of immersion in 3.5 wt.% NaCl solution. Visual observations of coating samples exposed to 3.5 wt.% NaCl solution after 300 h of immersion: (c) neat EP/Zn, (d) GO/EP/Zn, and (e) PGO/EP/Zn, with a circle diameter of 1.1 cm in each image [88].

Figure 9

SEM images of bare Cu (a) before and (d) after immersion, PE-coated Cu (b) before and (e) after immersion, and PE/G 1.25%-coated Cu (c) before and (f) after immersion. (g) Schematic illustration of the PE/G composite coating on copper. (h) Tafel plots of Cu, PE, PE/G 0.25%, PE/G 0.5%, PE/G 0.75%, and PE/G 1% in 3.5 wt.% NaCl aqueous solution [89].

Figure 10

(a) Preparation process of G@PmPD. (b) ∣Z∣_{10m Hz} and (c) f_b values for EP, PmPD_0.5/EP, G_0.5/EP, G@PmPD_0.5/EP, and G@PmPD_1.0/EP coatings as a function of immersion time. (d) Fitting results of R_ct for different scratched samples [90].

Figure 11

(a) Illustration of the self-repairing mechanism, where hydrogen bonds form upon water absorption, enabling healing. (b) Changes in water permeability for coatings in different states, highlighting the effect of the self-healing process. (c) EIS results of the PEI-PAA with GO-containing (GO-0 wt%, GO-0.025 wt%, GO-0.05 wt%, and GO-0.1 wt%) coatings exposed to air following 360 h of immersion in a 3.5 wt.% NaCl solution, demonstrating corrosion resistance [91].

Figure 12

(a) Schematic illustration of the preparation process for GOH, GOE, and GOEH. (b) Adhesion strength of the specimens measured by pull-off testing. (c) Illustration of the corrosion protection mechanism for GOEH/WEP composite coatings [81].