Advanced Anticorrosive Graphene Oxide-Doped Organic-Inorganic Hybrid Nanocomposite Coating Derived from Leucaena leucocephala Oil

Abstract

Metal corrosion poses a substantial economic challenge in a technologically advanced world. In this study, novel environmentally friendly anticorrosive graphene oxide (GO)-doped organic-inorganic hybrid polyurethane (LFAOIH@GO-PU) nanocomposite coatings were developed from Leucaena leucocephala oil (LLO). The formulation was produced by the amidation reaction of LLO to form diol fatty amide followed by the reaction of tetraethoxysilane (TEOS) and a dispersion of GO_x (X = 0.25, 0.50, and 0.75 wt%) along with the reaction of isophorane diisocyanate (IPDI) (25-40 wt%) to form LFAOIH@GO_x-PU₃₅ nanocomposites. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR); ¹H, ¹³C, and ²⁹Si nuclear magnetic resonance; and X-ray photoelectron spectroscopy. A detailed examination of LFAOIH@GO_0.5-PU₃₅ morphology was conducted using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. These studies revealed distinctive surface roughness features along with a contact angle of around 88 G.U preserving their structural integrity at temperatures of up to 235 °C with minimal loading of GO. Additionally, improved mechanical properties, including scratch hardness (3 kg), pencil hardness (5H), impact resistance, bending, gloss value (79), crosshatch adhesion, and thickness were evaluated with the dispersion of GO. Electrochemical corrosion studies, involving Nyquist, Bode, and Tafel plots, provided clear evidence of the outstanding anticorrosion performance of the coatings.

Keywords: bio-resource; coating; corrosion inhibition; nanocomposite; organic-inorganic hybrid; polyurethanamide.

Scheme 1

Synthesis of LFAOIH-PU.

Scheme 2

Synthesis of LFAOIH@GO-PU.

Figure 1

FTIR spectra of (1) LLFAD, (2) LFAOIH, (3) LFAOIH@GO, (4) LFAOIH−PU₃₅ and (5) LFAOIH@GO_0.5-PU₃₅.

Figure 2

(a) ¹H, (b) ¹³C and (c) ²⁹Si NMR spectra of LFAOIH and LFAOIH-PU, respectively.

Figure 3

XPS analysis of LFAOIH@GO_0.5−PU_35, (a) Survey spectrum, (b) C 1s peaks, (c) O1s peaks and (d) N1s 1s peaks and (e) Si 2p.

Figure 4

XRD thermograms of LFAOIH and LFAOIH@GO_0.5-PU₃₅.

Figure 5

(a) DSC and (b) TGA/DTG thermograms of LFAOIH and LFAOIH@GO_0.5-PU₃₅.

Figure 6

Contact angle analysis of (a) LFAOIH and (b) LFAOIH@GO_0.5-PU₃₅.

Figure 7

SEM and EDX micrograph of LFAOIH@GO_0.5-PU₃₅.

Figure 8

TEM micrograph of LFAOIH@GO_0.5-PU₃₅ at 100 nm and 200 nm.

Figure 9

EIS and Bode theta analysis for LFAOIH-PU₃₅ for various (1, 3, 9, 12) days.

Figure 10

EIS and Bode theta analysis for LFAOIH@GO_0.5-PU₃₅ for various (1, 3, 9, 12) days.

Figure 11

Tafel analysis for LFAOIH-PU₃₅ and LFAOIH@GO_0.5-PU₃₅ for various (1, 3, 9, 12) days.