Novel modified poly(styrene-co-maleic anhydride) for corrosion inhibition and its effect with waterborne polyurethane dispersion: Synthesis, characterization, and performance

An environmentally friendly organic coating system was developed by incorporating a novel corrosion-inhibiting polymer (PHDS) into a waterborne polyurethane dispersion (WPUD) matrix, demonstrating enhanced protective performance. The inhibitor polymer was synthesized by functionalizing poly(styrene- co -maleic anhydride) (SMA) with tris (hydroxymethyl)aminomethane) and characterized by FTIR and ¹H NMR techniques. A polycarbonate-based aliphatic WPUD was synthesized to integrate the PHDS, offering a VOC (Volatile Organic Compound)-compliant and mechanically resilient matrix. Electrochemical impedance spectroscopy and Tafel polarization analyses confirmed a significant enhancement in corrosion resistance for St37 carbon steel immersed in 3.5 % NaCl solution, with a peak inhibition efficiency of 95.8 % at 3 % PHDS within 24 h of measurements. SEM and EDAX results demonstrated effective film formation and surface protection, while adhesion and salt spray tests highlighted the durability and feasibility of the coatings for application. Adsorption studies revealed a mixed-mode adsorption mechanism, best described by the Langmuir isotherm. The synergistic interaction between the PHDS and WPUD matrix reinforces the potential of this hybrid system as a next-generation anticorrosive organic coating for industrial environments.