Comprehensive evaluation on the encapsulation performances of melamine-formaldehyde microcapsules affected by core oils

Core oils' properties are significant for the microencapsulation process. 12 representative single componential core oils with different chemical structures, logP, solubility, interfacial tension (IFT) and viscosity were specially selected to fabricate melamine-formaldehyde (MF) microcapsules. Afterward, the effect of core oils' properties on the performance of microcapsules was investigated. It was found that the morphology, the average particle sizes (7.83 µm∼27.06 µm), the encapsulation efficiencies (47.35 ± 3%∼92.86 ± 4%), zeta potentials (−52.37 ± 2.97 mV∼−65.03 ± 0.79 mV) and the rupture forces (0.28 ± 0.20mN∼0.82 ± 0.3mN) of microcapsules were influenced by core oils' properties. Further comprehensive analysis indicated that logP≥ 1.66 and the solubility≥ 0.055 mL3/g were the premises for the successful encapsulation processes. Moreover, by increasing logP, IFT and viscosity, the size of microcapsules increased; as microcapsules size increased, the release rate decreased; the high IFT and the solubility increased the encapsulation efficiency of microcapsules; the mechanical property was influenced by logP. This work provided to use logP as the criterion to predict the encapsulation work, which hasn't been studied before; and the correlations between microcapsules' various performances and core oils' properties were initially established. This work was meaningful since logP was used as a clear criterion to select core oils for encapsulation work and core oils' properties were used to predict the application performances of microcapsules.