Star-shaped block copolymers. IV. Emulsifying activity in the water–oil emulsions

Water–organic solvents emulsions based on toluene, n hexane, n-dodecane, and decaline are stabilized by new A(B)₂ star-shaped block copolymers. B is a polyoxirane block and A a polydiene or polyvinyl one. The influence of the molecular parameters of the copolymers has been studied; low-molecular-weight (±5000) copolymers containing 50% of polyoxirane have the originality to generate both O/W and W/O stable emulsions. The importance of the molecular architecture of block copolymers on their stabilizing efficiency has been put in evidence. For instance, 7/3 water–toluene emulsions are more efficiently stabilized by star-shaped block copolymers, whereas linear block copolymers give better results for 3/7 water–toluene emulsions.