Investigation of dialkyldimethylammonium bromides as stabilizers and/or emulsifiers for O/W emulsion

The emulsifying and/or stabilizing properties of dialkyldimethylammonium br omides (the alkyl chain-lengths 8, 10 and 12 carbon atoms) were investigate d by dynamic light scattering technique. The multimodal size distribution, effective diameter and zeta potential of the n-tetradecane droplets in 0.5 M n-propanol (and/or the bromide) solution were studied as a function of ti me. The parameters were determined with the help of ZetaPals/BI-MAS (Brookh aven Instrument Co.) apparatus. Following the droplet size determination in the emulsion, the zeta potential was measured for the same sample placed i n the measuring cell. The results obtained show that the surfactant molecul es are easily adsorbed on the surface of newly formed oil droplets. The sta bilizing properties of these bromides depend on the alkyl chain-length, the bromide concentration and the method of emulsion preparation. These bromid es were also tested as the emulsifying agents, without the presence of alco hol. It was found that, at appropriate conditions, they could be used as em ulsifiers only. However, more investigations are needed with other emulsion systems to better determine their emulsifying properties. A possible stabi lizing mechanism by which they interact in the oil-in-water emulsions is di scussed. (C) 2001 Elsevier Science B.V. All rights reserved.