The effects of the alkyl chain length of non-ionic surfactants on micellar structure and micellar inner polarity have been investigated. The aggregation number increases while the degree of hydration decreases with increased alkyl chain length. Also, a decrease in micellar inner polarity is found to occur as the alkyl chain length increases. An interpretation of these results is given.

From the relationship between the distribution width of oxyethylene (OE) or alkyl chains and O/W emulsions stability, it became evident that even with the same average OE or alkyl chain lengths, the phase‐inversion temperature (PIT) and O/W emulsion stability depend on width. However, emulsification at the PIT invariably results in a very stable O/W emulsion. Emulsifiers with a large distribution width of OE or alkyl chains were also found to improve O/W emulsion stability.

Thin layer chromatography with a flame ionization detection (TLC‐FID) technique was applied to the separation and determination of nonionic surfactants containing oxyethylene (OE) chains. The OE adducts with an average number of 4.2, 6.0 and 8.0 oxyethylene units were separated on Chromarod S‐II (Silica gel‐coated rods) with double development using benzene:ethyl acetate (6:4) and ethyl acetate:acetic acid:water (8:1:1). OE adducts of nonionic surfactants were well separated by the TLC‐FID method using simple and standard techniques that eliminate the need for any chemical modification.