Low Breakage and Size-controlled Preparation of NiCl2 Immobilized Hollow Polyurea Microcapsules*

Polyurea microcapsules containing NiCl2 were prepared by interfacial polymerization between diisocy-anate and water witii triethylamine as a catalyst in water-in-oil emulsion system. The influence of preparation conditions such as the dosage and feed mode of die catalyst, concentration of the encapsulated NiCl2, and concentration and structure of diisocyanates on the breakage of the microcapsules have been evaluated. The results show that breakage is strongly dependent on the rate of polymerization and stability of initial emulsion. The improved microcapsules with low breakage have been produced under the optimum conditions. Furthermore, die obtained microcapsules immobilizing NiCl2 as a recyclable catalyst is successfully used in benzaldehyde reduction.