Preparation and barrier properties of the microcapsules added nanoclays in the wall

Preparation of microcapsules applied to the fabrication of self-healing composites has attracted a lot of attention. However, the leakage of core material from the microcapsule is a major problem in self-healing microcapsules. Proper dispersion of layered silicates within the wall of microcapsule is a strategy for improving the barrier properties of the microcapsule. In the present study,poly(urea-formaldehyde) (PUF) microcapsules containing dicyclopentadiene (DCPD) were prepared by in situ polymerization. For the preparation of UF/clay nanocomposite microcapsules, acid-modified montmorillonite (H-MMT) was used as an effective catalyst for the condensation of urea and formaldehyde, and the condensation polymerization in the galleries resulted in the delamination of the clay, as confirmed by TEM and XRD analysis. Scanning electron microscopy (SEM) was applied to observe the morphology of the microcapsules and the barrier property of microcapsules was investigated by thermal gravimetry (TG) analysis and mass release method. On comparison with conventional microcapsules (CMs), nanocomposite microcapsules (NCMs) have better barrier property. This can be attributed to the nanocomposite structure of the microcapsules, where nanosized montmorillonite dispersed in UF to decrease the core material cross-over. Copyright (C) 2008 John Wiley & Sons, Ltd.