Corrosion protection performance evaluation of chemically synthesized copolymer (pyrrole-co-p-chloroaniline) coatings on 316L SS surface in HCl medium

• S.A. Alasaddy¹, A.M. Farhan² and A.A. Jabor³

¹ Department of Chemistry, College of Science, University of Baghdad, Jadriya, 10011, Baghdad, Iraq
² Department of Chemistry, College of Science for Women, University of Baghdad, Jadriya, 10011, Baghdad, Iraq
³ Ministry of Higher Education and Scientific Research, Scientific Research Commission, Baghdad, Iraq

Abstract: Coatings are the most direct and effective technique to prevent metal corrosion. Environmental protection demands unique eco-friendly materials with strong corrosion protection, which have been intensively explored. “A coating of poly (pyrrole-co-p-chloroaniline) was produced on stainless steel 316L for increased protection. This was achieved through chemical oxidative copolymerization of a 1:1 mixture of pyrrole and p-chloroaniline monomers in a 0.1 M HCl corrosive solution, using ammonium persulphate as an oxidant. The copolymer’s crystalline nature, functional group, chemical content, and form were examined using XRD, FT-IR, UV-visible, EDX, FESEM, and AFM. The XRD spectra for the pyrrole/p-chloroaniline copolymer showed an amorphous structure. Fourier-transform infrared spectroscopy (FTIR) revealed the functional groups of the chemical structure. Copolymer thin films were deposited using the chemical bath deposition (CBD) method, which resulted in an optical band gap of 1.5 eV. Energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of chlorine (Cl), carbon (C), and oxygen (O) in the thin film. The morphology of the copolymers was irregular, aggregated, and cauliflower-like with a spherical shape. Finally, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to test the functional coatings’ mechanical and thermal properties. Tafel and polarization charts were used to assess the deterioration of the coated. The corrosion potential, polarization resistance, and corrosion current were measured from these tests. The results reveal that the poly (pyrrole-co-p-chloroaniline) coating provides excellent protection for SS316L under corrosive conditions. The coating demonstrated a high protection efficiency, achieving 99.97%, 99.98%, 99.96%, and 99.90% across a temperature range of 298–328 K.

Keywords: conducting polymers, corrosion, poly(pyrrole-co-p-chloroaniline), polymer coatings, metal substrate, corrosion

Int. J. Corros. Scale Inhib., 2025, 14, no. 3, 1434-1457
doi: 10.17675/2305-6894-2025-14-3-21

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