Studies on Microcapsules. XIII. Effect of Span 85 and pH of Aqueous Phase on the Formation of Polyamide Microcapsules

Abstract

Abstract The effects of the pH of aqueous phase containing piperazine and the concentration of Span 85, a nonionic surfactant with chemical description of sorbitan trioleate (Atlas Power Co., U.S.A) on the formation of polyphthalamide microcapsules were systematically investigated by the interfacial polycondensation method in the organic phase containing p-phthaloyl dichloride. The presence of Span 85 facilitated the formation of microcapsules by increasing the transfer of undissociated diamine molecules into the organic phase in the pH range 9.0–12.0, outside of which Span 85 did not significantly contribute to the formation of microcapsules. An increase in the pH in this range gives rise to an increase in the number of undissociated diamine molecules, promoting the transfer of diamine.