High‐Performance Neat Polyurea Coating for Mechanical Protection

ABSTRACT 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.