Peripherally decorated binary microcapsules containing two liquids†

In this work, 1.4 mm dibutylphthalate (DBP) filled urea–formaldehyde (UF) microcapsules were used as Pickering stabilizers to create larger 140 mm microcapsules containing a second liquid phase, dicyclopentadiene (DCPD). The binary microcapsules were made by encapsulating the dispersed DCPD liquid (stabilized with the UF(DBP) microcapsules in water) via an isocyanate–alcohol interfacial polymerization reaction. Fluorescent optical microscopy and scanning electron microscopy (SEM) showed that the resulting microcapsules have a central liquid core decorated at its periphery with a layer of microcapsules containing the second liquid. The presence of both the encapsulated liquids within a single capsule structure was demonstrated by differential scanning calorimetry (DSC). DSC data analysis indicated a DBP volume fraction of 8.8%. This value was validated by the calculated theoretical fraction on the basis of the observed architecture and capsule dimensions.