Cobaltocenium-Based Zwitterionic Metallo-polyelectrolyte: Facile Synthesis, Synergetic Water Lubrication and Anticorrosion

Abstract A cobaltocenium-based zwitterionic polymer with an unsaturated polycyclooctene backbone (PCOE-Co+S–) is designed and synthesized via ring-opening metathesis polymerization (ROMP), affording controlled molecular weight (Mw of 12.5–59.7 kDa) and an acid-resistant backbone. Taking advantage of the hydration property of the cobaltocenium-containing zwitterionic unit and the flexibility of the hydrophobic polycyclooctene backbone, the cobaltocenium-containing zwitterionic polymer can be used as a synergetic water lubrication and anticorrosion agent. As a water-based additive, it exhibits a reduction in the coefficient of friction >50% (to 0.158–0.163) and wear volume reduction >75%; as a corrosion inhibitor, it exhibits corrosion inhibition efficiency as high as 93% at only 50 mg/L in 5 wt % HCl. The dual functionality originates from a synergetic mechanism: the triazole-linked cobaltocenium-mediated surface anchoring combined with sulfonate-enabled hydration and hydrophobic backbone barrier formation. This work demonstrates that backbone engineering of a zwitterionic polymer offers a viable route to integrate lubrication and corrosion protection into one polymer platform.