Preparation of microcapsules that produce color in response to humidity for use in intelligent functional paper

In this study, a microcapsule that produces color in response to moisture in air was produced for use in an intelligent functional paper which is able to self-color after a fixed time. This microcapsule containing FeSO4 as the coloring material was prepared from gelatin and terephthaloyl chloride by an interfacial polymerization technique and was modified by a 2-propanol solution of glycerin to supplement the moisture sensitivity. A microcapsule membrane was formed by crosslinking between the amino group at the end of the gelatin and the carbonyl group of the terephthaloyl chloride. The time required for the microcapsules to produce the color tended to increase with decreasing amounts of the glycerin 2-propanol solution used for the soaking treatment of the microcapsules or increasing amounts of FeSO4 in the microcapsules. (C) 2005 Springer Science + Business Media, Inc.