Ester Exchange Modification for Surface-Drying Time Control and Property Enhancement of Polyaspartate Ester-Based Polyurea Coatings

In recent years, polyurea (PUA) systems have drawn considerable attention in the coatings industry for their superior performance. Among these systems, polyaspartate ester-based polyurea (PAE-PUA) stands out for its excellent comprehensive properties, and the structure of the diamines used in polyaspartate ester (PAE) significantly influences key performance attributes, such as gel time, mechanical properties, and thermal stability. To investigate the influence of diamine structures on PAE-PUA properties, this study synthesized PAEs through ester exchange reactions involving diamines and monohydric alcohols with varied chain lengths and structural types (linear or cyclic). The effects of four diamines (D230, DMH, IPDA, PACM) and four monohydric alcohols (CA, DDA, OD, CHOL) on polyurea coating properties were systematically examined. The results demonstrated that adjusting the structural regularity of PAEs via ester exchange reactions effectively regulated their viscosity, maintaining it below 1500 mPa·s. These reactions also enabled simultaneous regulation of surface-drying time, mechanical properties, and thermal performance. Notably, introducing 1-octadecanol (OD) significantly improved surface-drying time and thermal stability, whereas cyclic structures in diamines or alcohols resulted in higher glass transition temperatures (Tg). Additionally, the mechanical properties and reaction rates of modified PAEs can be tailored to meet specific application requirements, offering an effective strategy for developing polyurea materials optimized for the coatings industry.