A New Approach to Studying Microcapsule Wall Growth Mechanisms

Polyurea microcapsules were prepared by sequential interfacial reaction of different aromatic and aliphatic isocyanates. The resulting composite capsule walls were studied using scanning transmission X-ray microscopy (STXM) to quantitatively map the distributions of the resulting aromatic and aliphatic polyureas across the capsule wall. Application of this method to both cross-linked and non-cross-linked polyurea capsules resulted in observation of different capsule wall growth mechanisms, depending mainly on the choice of monomers.