The use of terpolymers, obtainable by free radical copolymerization of (a) at least one anhydride of a C.sub.3-C.sub.10-dicarboxylic acid, (b) at least one 1,1-di-(C.sub.1-C.sub.3-alkyl)-substituted C.sub.4-C.sub.8-olefin, (c) polyisobutene having an average molecular weight M.sub.n in the range of from 200 to 10 000 g/moland, if appropriate hydrolysis,for the preparation of aqueous emulsions or dispersions of hydrophobic substances with the use of not more than 2% by weight of further emulsifier, based on the total aqueous emulsion or dispersion.