The present invention relates to aqueous dispersions comprising (A) at least one (co)polymer of at least one branched or straight-chain C.sub.3-C.sub.10-alkene, (B) at least one emulsifies synthesized by (a) preparation of a (co)polymer of isobutene, the (co)polymer having at least one reactive group, (b) functionalization of the (co)polymer of at least one branched or straight-chain C.sub.3-C.sub.10-alkene, (c) incorporation of at least one hydrophilic unit.