T. Engels et al., THE INFLUENCE OF COEMULSIFIER TYPE ON THE STABILITY OF OIL-IN-WATER EMULSIONS, Colloids and surfaces. A, Physicochemical and engineering aspects, 99(2-3), 1995, pp. 141-149
Oil-in-water emulsions containing ethoxylated non-ionic surfactants ma
y undergo a phase inversion to water-in-oil emulsions on heating. This
temperature-induced phase inversion is utilized in the so-called phas
e inversion temperature (PIT) method for the preparation of finely dis
persed bluish oil-in-water emulsions. PIT emulsions with polar oil com
ponents were prepared by adding mixtures of fatty alcohol ethoxylates
with or without the coemulsifier glyceryl monostearate. In the phase i
nversion temperature range, microemulsion or liquid crystalline phases
are formed depending on the type of emulsifier mixture used. The form
ation of a bicontinuous or lamellar structure is essential in order to
obtain finely dispersed oil-in-water emulsions. In both phases the hy
drophilic-lipophilic properties are balanced, which results in minimum
interfacial tensions between oil and water phases. Fine dispersity, h
owever, is not the only criterion for stable oil-in-water emulsions. S
tudies of different parameters of the emulsions give hints to the stab
ilization mechanism of the emulsifier/coemulsifier system. According t
o these results, low viscous PIT emulsions exhibit long-term storage s
tability, if the oil droplets are shielded against coalescence by a la
mellar gel phase, which is imparted by the coemulsifier glyceryl monos
tearate.