SURFACE FREEZING A PATHWAY TO STABLE HIGH INTERNAL PHASE EMULTIONS (HIPE)

Linear alkanes and surfactants with similar chain lengths, when combined at a given temperature, may form a mixed monolayer of ordered molecules¹. This phenomenon is called surface freezing and can be used to stabilize emulsions².

In this work, the hanging drop method was used to measure interfacial tension as function of temperature and of the composition of the oil and aqueous phases to determine their surface freezing temperature.

With variations in composition, it was observed that higher surface freezing temperatures (SFTs > 40^oC) occur when a co-surfactant such as hexadecanol is added. This finding was used to prepare highly stable emulsions, which could be concentrated to form HIPEs that remained stable over a few months when stored below their SFTs, but that where readily broken above it.