High-Performance Neat Polyurea Coating for Mechanical Protection

Polyurea coatings with high mechanical performance hold tremendous promise for mechanical protection. However, high-performance neat polyurea remains a significant challenge, and the interrelationships among synthesis, microstructure, and properties are poorly understood, thereby limiting its applications and potential for further enhancement. This study synthesized a neat polyurea using isophorone diisocyanate (IPDI), polyetheramine J2000, and J230 as the only three basic reactants, by employing a two-step process that features the secondary addition of IPDI. Extensive measurements revealed superior properties, including a tensile strength of 52 ± 3 MPa, elongation at break of 1807% ± 100%, thermal decomposition temperature of 300°C, and glass transition temperature of −56°C, along with remarkable resistance to impact and corrosion. Molecular analysis and microstructure observation unveiled that these superior properties likely originated from a linear long-chain structure, enhanced by the synergistic effects of ultra-short-range microphase separation and lateral crosslinking by trimers. Simultaneously, further optimization was achieved by controlling the fraction of short ring chains and intermolecular hydrogen bonds. High-performance polyurea coatings show great potential for aerospace and lightweight protection. Neat polyurea with excellent mechanical properties provides a solid foundation for further applications and modifications.