Preparation and performance assessment of high-strength polyurea microcapsules

Formulation of microcapsules with high mechanical strength holds great significance for their application in high-pressure scenarios. In this study, polyurea (PU) was employed as the shell material to encapsulate perfume oil through interfacial polymerization. Subsequently, a systematic assessment of mechanical strength was conducted. The results indicated that the protective colloid, triethylenediamine (TEDA) concentration, core/shell ratio (perfume oil to polymethylene polyphenyl isocyanate (PAPI)), and reaction temperature, significantly influenced the mechanical strength of PU microcapsules. Notably, employing a concentration of 1.5 wt% polyvinyl alcohol (PVA), 0.5 wt% TEDA, a core/shell ratio of 10:1, and a reaction temperature of 70 °C resulted in PU microcapsules boasting an average rupture force of 1.92 ± 0.22 mN and a Young's modulus of 0.0195 ± 0.0013 GPa. Impressively, when contrasted with melamine-formaldehyde microcapsules, those with PU shells exhibited markedly enhanced mechanical properties.