## 3 Results
### Characterization of Dispersions of Pluronic-F-127-Decorated Silica Nanoparticles
(**b**) Dependence of the average apparent hydrodynamic diameter on the nanoparticle concentration for silica nanoparticle dispersions with Pluronic F-127, where the concentration of Pluronic F-127 is fixed at \(1\,\text{mg}/\text{mL}\). The lines in both panels are guides for the eyes. Exploring the effect of the nanoparticle concentration on the adsorption of Pluronic F-127 onto the silica surface in more detail, it is important to note that the apparent thickness of the Pluronic F-127 layer increases as the concentration of nanoparticles is decreased. This can be explained considering the effective area available for the copolymer's deposition. In fact, the lower the nanoparticle concentration, the smaller the area available for the adsorption; therefore, it is expected that there will be stronger competition between the Pluronic F-127 molecules and micelles for occupying the nanoparticles' surface, resulting in the formation of more disordered layers with a higher fraction of Pluronic F-127 monomers protruding into the aqueous phase. This demonstrates the complexity of the concentration-dependent adsorption behavior and highlights the importance of understanding surface interactions. In a similar situation to the above, the effect of the silica nanoparticle concentration on the adsorption of Pluronic F-127 at a constant concentration (1 mg/mL) was examined. As the concentration of silica nanoparticles increased, there was a decrease in the apparent hydrodynamic diameter of the copolymer-nanoparticle complexes. The association of Pluronic F-127 and silica nanoparticles in the aqueous bulk can also be evaluated in terms of the effective charge of the decorated colloids, evaluated as the \(\zeta\) potential (see Figure 3). The results show a progressive shift of the \(\zeta\) potential value, moving from that of the unmodified particles to values close to electroneutrality. Based on this result, it can be assumed that the formation of the Pluronic F-127 shell on the silica surface shields the negative charge on the nanoparticle. Consequently, the stability mechanism of the particles in the aqueous medium shifts from electrostatic stabilization to steric stabilization, leading to the formation of core-shell colloids. These colloids consist of an inner core composed of silica nanoparticles, while the outer shell is formed by the capping Pluronic F-127 layer (see references [17; 18] for a sketch of the core-shell decorated colloids). In addition, the dependence of the coating density on the number of nanoparticles dispersed in the aqueous medium is supported by the observed reduction in the effective charge of the copolymer-decorated nanoparticles with increasing nanoparticle concentration. As mentioned earlier, a higher particle concentration results in a limited availability of Pluronic F-127 to coat each individual particle. Figure 3: (**a**) Dependence of the \(\zeta\) potential on the concentration of Pluronic F-127 for the mixed dispersions. (\(\blacksquare\)) \(c_{\text{NP}}=0.1\%\)\(w/w\) and (\(\bullet\)) \(c_{\text{NP}}=1\%\)\(w/w\). (**b**) Dependence of the \(\zeta\) potential on the nanoparticle concentration for silica nanoparticle dispersions with Pluronic F-127, where the concentration of Pluronic F-127 is fixed at 1 mg/mL. The lines in both panels indicate the \(\zeta\) potential value corresponding to the bare silica nanoparticles, and the error bars represent the standard deviation of five independent measurements.