STUDY OF THE INTERFACIAL POLYCONDENSATION OF ISOCYANATE IN THE PREPARATION OF BENZALKONIUM CHLORIDE LOADED MICROCAPSULES

The preparation of benzalkonium chloride loaded microcapsules was perf ormed by interfacial polycondensation of isocyanates. The present stud y was made in order to clarify parameters affecting microcapsule wall formation during the course of polymerization. The results presented h ere show that many interrelated parameters are involved during the mic rocapsule formation. Each individual component introduced in the prepa ration was shown to have an effect either on the morphology of the mic rocapsules or on the mechanical resistance. Benzalkonium chloride seem ed to interact mainly in the interfacial polymer precipitation step th rough a salt effect, or influence the polycondensation reaction rate a cting as a catalyst. A contribution of the hydroxylic functions of the surfactant in the polycondensation reaction of the isocyanate was als o highlighted. Finally, the organic phase composition was found to be able to modulate the reactivity of hydroxylic functions of the surfact ant, leading to very slow reactions in pure xylene. These effects were related to the characteristics of the microcapsules obtained accordin g to different compositions of the formulation system.