STABILIZATION OF OIL-IN-WATER EMULSIONS BY NON-IONIC DETERGENTS - ELECTRICAL AND ENTROPIC CONTRIBUTIONS TO STABILITY

Calculations of the attractive and repulsive forces between globules of anisole and chlorobenzene in the presence of non‐ionic detergents of varying polyoxyethylene chain length are presented. The equations of the Derjaguin‐Landau‐Verwey‐Overbeek theory are used and the effect on the attractive potential of the adsorption of stabilizer onto the particle is taken into account. The adsorbed film was found to increase the attractive forces between the particles, VA. In the previous paper (Elworthy & Florence, J. Pharm. Pharmac., 1969, 21, 70) it was shown that the electrical contribution to stability is a secondary stabilizing factor. More quantitative estimates of this contribution have been made. The entropic repulsion has been calculated using an equation of Ottewill & Walker. The energy‐distance diagrams are discussed in the light of the experimental results presented in the previous paper. 1969 Royal Pharmaceutical Society of Great Britain