Cyclotriphosphazene based dendrimeric epoxy resin as an anti-corrosive material for copper in 3% NaCl: Experimental and computational demonstrations

Present study deals with the synthesis, characterization and corrosion inhibition effect of a hexafunctional cyclotriphosphazene derivative, namely 2,2,4,4,6,6-hexakis(oxiran-2-ylmethoxy)-1,3,5,2δ,4δ,6δ-triazatriphosphinine(HPGCP)for copper in 3 wt% NaCl medium. The synthesized HPGCP was characterized using numerous spectral techniques such as¹H, ¹³C, ³¹P NMR (Nuclear magnetic resonance) and Fourier-transform infrared spectroscopy (FT-IR) methods. Anti-corrosive effect of the HPGCP was measured using electrochemical and computational methods. Results showed that HPGCP exhibited highest protection efficiency of 95% at as low as 10⁻³ M concentration. Polarization studies showed that HPGCP acted as mixed type inhibitor and its adsorption obeyed the Langmuir adsorption isotherm model. Density Functional Theory (DFT) based computational studies demonstrate that HPGCP interacts with copper surface using donor-acceptor interactions in which three nitrogen atoms and six π-electrons of the cyclotriphosphazene ring play significant role in metal-inhibitor interactions. Molecular dynamic (MD) simulations study demonstrated that HPGCP spontaneously interacts with metallic surface using its electron rich centers and acquires the planar orientation. Experimental results were well corroborated with the computational results.