Abstract
Emulsions composed of oil and water are typically stabilized by emulsifiers (e.g., surfactants and
amphiphilic polymers) because oil and water are immiscible with each other. However, since the emulsions
are thermodynamically unstable even upon the utilization of emulsifiers, the colloidal stabilization of
emulsions remains a challenging task. To this end, we have investigated the colloidal stability of oil-in-water
(O/W) emulsions in the absence of any emulsifiers such as surfactants and amphiphilic polymers (named as
emulsifier-free or surfactant-free O/W emulsions) in order to evaluate the essential features of colloidal
stabilization of O/W emulsions. Recently, we found that the paraffin-in-water emulsion was destabilized with
the addition of L-menthol to paraffin. Then, we applied the polar oils for stabilization the
L-menthol-containing paraffin-in-water emulsions because the polar oils are expected to homogenize
L-menthol in paraffin droplets by the hydrogen bonding between L-menthol and polar oil. Indeed,
L-menthol-containing paraffin-in-water emulsions were stabilized with the addition of polar oil to paraffin.
