4. Controlled fragrance release without microcapsules

The most direct way to influence the olfactory rendering of a fragrance and its evolution over time is to take advantage of the interactions between the fragrance molecules and the cosmetic base, which often includes polar and apolar phases and surfactants. These phases usually coexist in the form of oil-in-water (O/W) or water-in-oil (W/O) emulsions, microemulsions (O/W) or (W/O), or lamellar, hexagonal or cubic mesophases, stabilized by varying quantities of surfactants. The resulting morphologies can be very diverse, as illustrated in figure 11