*3.1. Study of Particle Monolayers at the Bare Water*/*Vapor Interface*

The hydrophobic nature of the particles suggests that they may be spread at the bare interface leading to the formation of a particle-laden interface. Therefore, the evaluation of the incorporation of the particles at the bare water/vapor interface, in terms of their surface pressure (Π)-area (*A*) isotherms, can be useful as a preliminary step for understanding their incorporation into DPPC monolayers. Figure 1 shows the Π-*A* isotherms for SiO2 and CB particles at the bare water/vapor interface.

**Figure 1.** Π–*A* isotherms for CB () and SiO2 (•) particles at the bare water/vapor interface.

The isotherms point out that neither CB particles nor SiO2 ones affect the surface tension of the bare water/vapor significantly until the interfacial density of particle is large enough to form a highly packed film, which leads to the increase of the surface pressure of the monolayer.
