## 3 Results and Discussion  
### Size and Morphology of Electro-Sprayed mPCM  
The size, the surface state, and the morphology of electro-sprayed mPCM were characterized by SEM and OM observations (Figure 1). They are mainly influenced by the PCM content, the phase change temperature of the PCMs used during the process, and also the choice of the solvents. Blank PCL particles present a spherical shape, whatever the solvent selected to solubilize PCL, i.e., chloroform or ethyl acetate (Figure 1(n1,n2)). The use of chloroform allows the particles to have a smooth surface state. In contrast, the solubilization in ethyl acetate solution leads to the formation of a single-pore morphology as previously described by [PERSON] et al. [45]. Adding PCMs in the working solution does not have a substantial effect on the obtained morphology, since the obtained particles are also spherical. Nevertheless, the increase of _n_-alkanes in the solution leads to an increase in the mean diameter and the particle size distribution. Furthermore, in the case of the use of EA as the solvent, single-pore morphology turns to a non-porous morphology for PCM/PCL blends. The use of \(n\)-hexadecane and \(n\)-eicosane does not lead to the same granulometric properties, even if their molecular chain length differs by four carbon atoms. \(N\)-hexadecane is in its liquid state at room temperature, while \(n\)-eicosane is in its solid state. Under the action of Coulombic repulsions, the break-up process of \(n\)-eicosane/PCL charged droplets is different from that of \(n\)-hexadecane/PCL  
Figure 1: Scanning electron microscopy (SEM) and optical microscopy (OM) graphs of neat poly(caprolactone) (PCL) microspheres and mPCM obtained from different conditions (**n1**) neat PCL microspheres obtained from chloroform (**n2**) neat PCL microspheres obtained from ethyl acetate (**a1–a3**) \(n\)-hexadecane/PCL/chloroform microcapsules (**b1–b3**) \(n\)-eicosane/PCL/chloroform microcapsules (**b1–b3**: Their surface morphologies) (**c1–c3**) \(n\)-hexadecane/PCL/ethyl acetate microcapsules (**d1–d3**) \(n\)-eicosane/PCL/ethyl acetate microcapsules (**d1–d3**: their surface morphologies) (scale bar: 200 \(\upmu\)m) (**b1–b3**s and **d1–d3s**) the magnification SEM images of related sample surface morphology (scale bar: 50 \(\upmu\)m). one. During the flying process, from the nozzle to the collector, droplets containing \(n\)-eicosane start their solidification at the earliest stages due to the evaporation of the solvent, which induces an enhancement of \(n\)-eicosane chain interactions and, therefore, their crystallization. Therefore, it leads to a higher specific surface to volume ratio, which prevents the further break-up process of the electro-sprayed droplets, unlike \(n\)-hexadecane, which is in a liquid state throughout the process. Furthermore, the crystallization being an exothermic phenomenon increases the local temperature in the inner core of the droplets, which leads to a growth of the solvent evaporation rate. Therefore, the use of \(n\)-eicosane leads to the formation of particles having a higher mean diameter and particle size distribution than with \(n\)-hexadecane one. Since solid particles are obtained in the earliest stages of the flying process, in the last steps, the solvent release results in the obtaining of the rough and wrinkled surface state of the particles, which is more pronounced with the increase of \(n\)-eicosane content. Thus, the black color observed in OM micrographs of \(n\)-eicosane/PCL particles belonged to \(n\)-eicosane laying on the surface of the PCL matrix (Figure 1(b3,d3)). At low content in \(n\)-eicosane, the core compound is completely entrapped by the PCL shell, but when it increased due to the thermodynamical phenomena and solvent evaporation, it diffuses on the surface of the particles. The granulometric properties of the electro-sprayed particles, as well as their morphology, are also affected by the solvent choice, that is used to solubilize the polymer and the \(n\)-alkane.