New lyotropic, fragranced, viscoelastic fluid with a
complex structure
is obtained from fragranced microemulsions by the addition of a fatty
acid. Nonhomogeneous mixing of an appropriate nonionic surfactant,
a fatty acid, and a fragrance oil led to the formation of anisotropically
shaped and highly oriented micelles in aqueous solution. The nano-
and microstructures, and consequently the viscosity, are controlled
by the balance of fatty acids used as a cosurfactant and fragrance
molecules, which partly behave as a cosurfactant and partly segregate
in the micelles of the hydrophilic nonionic surfactant. The transition
from isotropic microemulsion to a more structured viscoelastic solution
is characterized by X-ray scattering and rheological methods. Considering
our X-ray scattering results, we propose a structure composed of planar
sheets of ellipsoidal micelles arranged in a lamellar type of stacking.
The complex structured, low viscous, transparent fluid is capable
of solubilizing a fragrance inside the ellipsoidal micelles, as well
as retaining microparticles containing fragrance, without the addition
of a polymeric thickener or another gelator. These features allow
the creation of a 2-in-1 fragrance-solubilizing liquid product compatible
with all types of home and body care consumer products.