Metallo-Polyelectrolyte-Based Waterborne Polyurethanes as Robust HCl Corrosion Inhibitor Mediated by Inter/intramolecular Hydrogen Bond

Polyelectrolytes are commonly used as functional inhibitors and inhibitive coatings to protect metal from corrosion in the acidic condition. To achieve better inhibitive efficiency, both water solubility and supramolecular aggregated state of inhibitor on the metal surface should be considered in the design of robust inhibitors. Herein, a series of metallo-polyelectrolytes with cobaltocenium as the ionizable group and polyurethane as the backbone are designed and synthesized. The synthesized cobaltocenium-containing polyurethanes can be converted to waterborne polyurethane through a simple counterion exchange process. With regard to the multiple interaction between the synthesized metallo-polyelectrolytes and the metal surface as well as the inter/intramolecular hydrogen bonds between urethane groups, these cobaltocenium-containing waterborne polyurethanes display excellent anticorrosion performance. The polyurethane prepared from hexamethylene diisocyanate displays inhibitive efficiency as high as 98% at a concentration as low as 20 mg/mL toward mild steel in 4 M HCl.