Structure and Mechanical Properties of Acyl Hydrazide‐Modified Polyurea Elastomers Under Controlled Microphase Separation

ABSTRACT Polyurea (PU) elastomers have emerged as advanced engineering materials due to their toughness and chemical resistance. High‐performance elastomers have attracted widespread attention because of their broad applications in industry and daily life. However, achieving both high mechanical strength and toughness simultaneously remains a significant challenge in elastomeric materials. In this study, PU elastomers with excellent mechanical properties were prepared using rigid terephthalic dihydrazide (TPDH), toluene‐2,4‐diisocyanate (TDI), and soft polyether amine (PEA‐2000) segments. The role of acyl hydrazide groups was investigated in regulating the microphase separation behavior and mechanical properties of the PU elastomers. Through the systematic structural design of the soft and hard segments, the introduction of acyl hydrazide moieties significantly enhanced hydrogen‐bonding density while maintaining dynamic reversibility. This contributed to a substantial improvement in the stability and mechanical performance of the PU elastomers. The results indicate that when the molar ratio of TDI, TPDH, and PEA‐2000 is 1.04:0.8:0.2, the resulting PU elastomer exhibits a well‐defined microphase‐separated structure, with a tensile strength of 31 ± 1.1 MPa, an elongation at break of 158 ± 4.2%, a toughness of 4341 ± 366 J/m 3 , and a Shore hardness of 75. Regulating the microphase‐separated structure offers a novel design strategy for developing high‐performance PU elastomers with promising application potential.