The invention describes amphiphilic polymer compounds which are prepared by a) reacting a di-, tri- or tetraglycidyl compound (A) with an optionally unsaturated reactive component (B) consisting of C.sub.8-C.sub.28-fatty acid, a C.sub.8-C.sub.28-alcohol or a secondary C.sub.8-C.sub.28-amine, and allowing b.sub.1) the reaction product from stage a) to react further first with b.sub.1.alpha.) an aliphatic or aromatic polyisocyanate compound (C) b.sub.1.beta.) and optionally then with a polyalkylene oxide compound (D), and b.sub.1.gamma.) reacting the reaction product from stage b.sub.1.alpha.) or optionally b.sub.1.beta.) with a component (E) which is reactive towards isocyanates and has at least one OH, NH.sub.2, NH or SH group, or b.sub.2) allowing the reaction product from stage a) to react to completion with the reaction product of component (C) with component (E) and optionally (D) and (C), or b.sub.3) allowing the reaction product from stage a) to react to completion with the reaction product from component (C) and component (D) and optionally (C) and optionally the reaction product of component (C) and component (E) and optionally (C).The polymer compounds proposed according to the invention are exceptionally useful as agents for preventing or suppressing efflorescences on surfaces of hardened, hydraulically settable building materials or/and for hydrophobization of the corresponding hydraulically settable systems. Moreover, owing to the admixtures proposed according to the invention, the corresponding products absorb substantially less water, with the result that frost damage and rapid rusting of the steel reinforcement can be substantially reduced.