A route to high-solid coatings: Hydrophobic polyurethane triazoles via bulk polymerization of azide-alkyne cycloaddition

Abstract

In the present study, we showcase a series bulk polymerized siloxane-decorated polyurethane triazole coatings (Si-PUTs) achieved via azide-alkyne cycloaddition with excellent surface hydrophobicity and anti-corrosion properties. A simple functional modification converts aminopropyl trimethoxy silane to a dialkyne terminated monomer under mild conditions. Concurrently, a series of azide-terminated urethane monomers were synthesized by reacting azidoethanol with three common diisocyanates. Structural elucidation of the monomers was accomplished by FT-IR, 1H and 13C NMR along with ESI-MS. The azide-/alkyne- terminated monomer pairs undergo cycloaddition in absence of solvent and catalyst-free conditions to yield highly crosslinked siloxane-decorated polyurethane (Si-PUT) matrices post curing. FTIR and XPS analysis confirmed the successful formation of these Si-PUTs while the cure kinetics and reaction order was investigated by real-time FTIR. The physico-chemical properties of the polymers achieved were comprehensively assessed prior to evaluating their performance and feasibility as corrosion resistive coatings. The high contact angles in excess of 110°, transparency >85 % in the visible region, low Icorr, high polarization resistance, and corrosion rates in the order of 10−4 mm/year, all underscores the promise of Si-PUTs as excellent corrosion protection coatings. The encouraging results and ease of application demonstrate the potential to formulate environment friendly and multifunctional high-solid protective coatings.