Reduction of interfacial polycondensation self-limitation through solvent swelling to dynamically modulate shell thickness and structure of microcapsules

Abstract

The thickness and structure of microcapsule shell is the most important factor affecting essential performance of microcapsule. The growth of microcapsule shell prepared by interfacial polycondensation is self-limited which produces thin microcapsule shells with low mechanical strength. In this study, solvent dynamic swelling is employed to overcome the self-limitation of microcapsule shell prepared by interfacial polycondensation. It was found that the solvent dynamic swelling can enhance polyurethane shell and epoxy shell growth, and so that different shell structures could be regulated and the thickness of the shell could be increased. Finally, capsaicin microcapsules were prepared using epoxy resin as microcapsule shell, and capsaicin microcapsules with different core-shell structures were obtained by solvent regulation. The embedded microcapsule structure had lower release rate. The general effect of solvent evaporation and swelling on the interfacial polymerized microcapsule shell was explained, which provided a new paradigm for interfacial polymerized microcapsule shell structure regulation, especially the regulation of shell thickness.