## 3 Results
### Determining the Interfacial and Surface Energy of NPs  
The interfacial energy of the NP-CN and NP-SH with its polar \(\gamma_{NP/W}^{p}\) and dispersive \(\gamma_{NP/W}^{d}\) components was previously determined using the newly developed NanoTraPPED method by our group [35]. The interfacial energy with its polar and dispersive components of NP-Gly was determined in this work, using NanoTraPPED and the Owens-Wendt-Rabel-Kaelble (OWRK) [47; 48] model given by the following equation:  
\[\frac{\gamma_{P/W}(1+\cos\beta)}{2\sqrt{\gamma_{P/W}^{d}}}=\sqrt{\gamma_{NP/W} ^{p}}\sqrt{\frac{\gamma_{P/W}^{p}}{\gamma_{P/W}^{d}}}+\sqrt{\gamma_{NP/W}^{d }} \tag{1}\]  
where, \(\beta\) is the contact angle of the NPs at the three-phase line: NP-polymer (NP/P), NP-water (NP/W), polymer-water (P/W), as indicated by the subscript to the Greek letter \(\gamma\) throughout this work, \(\gamma_{P/W}^{p}\) and \(\gamma_{P/W}^{d}\) are the polar and dispersive polymer/water interfacial energy, \(\gamma_{NP/W}^{p}\) and \(\gamma_{NP/W}^{d}\) are the polar and dispersive nanoparticle/water interfacial tension and \(\gamma_{P/W}\) is the interfacial energy of polymer/water. Equation (1) was solved graphically, see Figure 2, by building a system of equations relating the contact angle \(\beta\) of the NP-Gly, on five different polymers listed in Table S3, with the surface energy components \(\gamma_{NP/W}^{p}\) and \(\gamma_{NP/W}^{d}\). Whereas the values for the polymer, \(\gamma_{P/W}^{p}\) and \(\gamma_{P/W}^{d}\) are known [35]. The contact angle was measured from the diameter of the circular voids or traces left be the NP-Gly on the surface of the polymer microspheres resulted from the Pickering emulsion polymerization and are shown in Figure S8, together with the obtained microspheres. The calculated contact angles are related to the diameter of the circular traces of the voids through the following geometric relationship: \(\beta=\pi-\sin^{-1}\frac{l}{r}\). The total surface energy and its components \(\gamma_{NP/W}^{p}\), \(\gamma_{NP/W}^{d}\) in water, are obtained by fitting the data to the linear Equation (1), where the \(\sqrt{\gamma_{NP/W}^{p}}\) is the slope and the \(\sqrt{\gamma_{NP/W}^{d}}\) is the intercept, as shown in the Figure 2. With this, the actual values of the \(\gamma_{NP/water}^{p}\), \(\gamma_{NP/water}^{p}\), and \(\gamma_{NP/water}\) are calculated and are given together with those for NP-CN and NP-SH in Table 1 and in Figure 2. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Nanoparticle** & \(\gamma_{NP/water}^{d}\) **(mN/m)** & \(\gamma_{P}^{p}\)**NP/water **(mN/m)** & \(\gamma_{NP/water}\) **(mN/m)** \\ \hline NP-SH & 0.21 & 3.10 & 3.10 \\ NP-CN & 0.00 & 2.77 & 2.77 \\ NP-Gly & 0.00 & 0.11 & 0.11 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Interfacial energy and its disperse \(\gamma_{NP/W}^{d}\) and polar component, \(\gamma_{NP/W}^{p}\) of the silica nanoparticles with water, bearing different surface functional groups. The data for NP-CN and NP-SH were taken from reference [35]. The total NP/w interfacial energy \(\gamma_{NP/water}\), Table 1, decreases in the order NP-SH > NP-CN > NP-Gly, suggesting the NP-Gly are wetted the most by water and are the most hydrophilic, while the NP-SH are the least wetted by water. Here we note that a vanishingly small value of the interfacial energy, see Table 1, implies complete wetting of a solid surface by a liquid and high work of adhesion energy, such as it is the case for NP-Gly, \(\gamma_{NP/water}=0.11\) mJ/m\({}^{2}\).