## 3 Results and Discussion
### Phase Change Properties of Electro-Sprayed mPCM  
The phase change temperatures and the latent heats of melting and crystallization of raw \(n\)-alkanes, neat PCL microspheres, and mPCM were obtained using differential scanning calorimeter. They are presented in Figures 3 and 4, and gathered in Tables 1 and 2. On the one hand, the latent heats of fusion of raw \(n\)-hexadecane and \(n\)-eicosane are 199, and 205 Jg\({}^{-1}\), respectively. Their melting and crystallization temperatures are found at 17.9 \({}^{\circ}\)C, 16.2 \({}^{\circ}\)C, 34.3 \({}^{\circ}\)C, and 35.7 \({}^{\circ}\)C. On the other hand, the onset of melting and crystallization temperatures of PCL microspheres are determined at 54.9 and 41.2 \({}^{\circ}\)C, when they have been prepared from ethyl acetate solution, and 55.6 and 41.5 \({}^{\circ}\)C from chloroform. The solvent used modifies to a limited extent the crystallinity since it is about 40.8% and 42.7% for the samples prepared from EA, and Chl, respectively. DSC thermograms of microencapsulated PCM have both the thermal transitions of the \(n\)-alkanes used and PCL. Figure 3: DSC cuves of \(n\)-hexadecane, neat PCL microspheres and a series of \(n\)-hexadecane/PCL microcapsules obtained from different solvents with different mass ratios between \(n\)-hexadecane and PCL. Figure 2: The fourier transform infrared spectroscopy (FT-IR) spectra of \(n\)-eicosane, \(n\)-hexadecane, neat PCL microsphere and a series of mPCM obtained from different conditions. The increase of \(n\)-hexadecane to PCL from 30 to 70 wt.% in the EA working solution results in the increase of the melting (and crystallization) enthalpy from 52 to 113 J:g-1, corresponding to an increase of the loading content from 26 to 56%, which is a quite lower than the theoretical content. On the other hand, the encapsulation efficiency reaches a maximum of 89% for 50 wt.%, then decreases to 81% for 70 wt.%. The loading content does not have a significant effect on the phase change transition temperatures, which are close to the raw \(n\)-hexadecane one. The mPCM obtained from chloroform solution have lower melting enthalpy than those with ethyl acetate. The encapsulation efficiency is slightly lower too. Furthermore, the melting and crystallization temperatures for low loading content are found relatively lower compared to the other content. The loss of \(n\)-hexadecane during electrospray microencapsulation results from the evaporation of the solvent in flight, which promotes phase separation between \(n\)-hexadecane and PCL, and sometimes the presence of pure tiny droplet of \(n\)-hexadecane. The rigidification of the PCL hindrances this phenomenon. \(n\)-hexadecane is highly soluble in chloroform than in ethyl acetate, and therefore, has a better compatibility [48,49]. Thus, the use of the chloroform working solution induces a higher loss in \(n\)-hexadecane during its evaporation. The use of ethyl acetate may prevent this phenomenon, and therefore, higher loading content in PCM in the microcapsules, are reached. Apart from \(n\)-hexadecane/PCL microcapsules, the thermal properties of \(n\)-eicosane-based mPCM, obtained from different solvents and various weight ratios between the \(n\)-alkane and PCL, are also presented in Figure 4 and Table 2. On the one hand, the presence of the PCL and the choice of the solvent used for the working solution does not affect the phase temperatures, which are quite similar to the raw \(n\)-hexadecane one. On the other hand, the use of chloroform allows entrapping higher content of \(n\)-eicosane (more than 10%) compared to the use of ethyl acetate. These results are the opposite of those obtained in the case of \(n\)-hexadecane, highlighting the influence or importance of the phase change that takes place during the process. Thus, the solvent evaporation, which occurs in the early stages of the electro-spraying process, induces a fast phase separation and further the PCM crystallization, which also promotes the stiffening of the PCL.