Comparison of oil-in-water emulsion films produced using ABA or ABn copolymers

Film thickness and disjoining pressure in emulsion films formed between two oil droplets in aqueous solutions of two ABA poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock copolymers of the Pluronic series, F108 and P104, were investigated at different NaCl concentrations. The microinterferometric thin film pressure balance experimental technique was used. The results obtained were compared with those previously reported for an ABn graft copolymer of hydrophobically modified inulin, namely INUTEC SP1. It was noted that there are marked differences in the behavior of the emulsion films stabilized with Pluronics ABA copolymers and those based on the ABn graft copolymer INUTEC SP1. This difference in behavior was used to throw some light on the difference in stability of practical emulsions when using these two types of polymeric surfactants. It is concluded that emulsions using INUTEC SP1 should be more stable than those using Pluronics ABA copolymers in particular at high electrolyte concentrations.