Microencapsulation of essential oils by single and coaxial electrospraying in poly ε-caprolactone microcapsules: characterization and oil release behavior

Electrospraying is a versatile, high-efficiency method for synthesizing microcapsules (MCs) with many applications. In this study, a single and a coaxial nozzle were used to prepare poly (ε-caprolactone) (PCL) MCs. The aim of this work was to investigate the influence of the encapsulation technique (single electrospraying (SE) and coaxial electrospraying (CE)) on morphology, particle size, chemical interactions, thermal properties, encapsulation efficiency, and release behavior. Thus, two natural oils with an insect-repellence effect (citronella and eucalyptus) were encapsulated in PCL MCs by means of SE and by CE. Spectroscopy, thermal, and microscopy characterizations of the MCs were performed. Oil encapsulation efficiency (EE) and release studies were also made. Spherical MCs with a mean diameter of 7–10 µm were obtained. Characterization techniques showed the presence of citronella and eucalyptus in the MCs and the chemical interactions between the polymer and the oils. In addition, higher encapsulation efficiency was achieved by CE for both oils. For MCs obtained by SE, a higher mass of oil released was observed compared to the capsules obtained by CE. Two released mechanisms were obtained in the systems depending on the oil used. The possibility of using MCs with different characteristics allows greater versatility of the particles.