Novel impact modifiers obtained by the reaction of amphiphilic block copolymers. These impact modifiers are suitable for use in thermosetting epoxy resin adhesives. The impact modifiers include a carboxylic acid group prepared from the reaction of an intramolecular anhydride of a di- or tricarboxylic acid with at least one amphiphilic block copolymer including at least one hydroxyl group. A method for adhesively binding heat-stable substrates includes applying a single-component thermosetting epoxy resin composition to the surface of a first heat-stable substrate; contacting the epoxy resin composition with the surface of second heat-stable substrate; heating the epoxy resin composition to 20-100° C.; bringing the two substrates and the epoxy resin composition into contact with a wash liquid; and heating the epoxy resin composition to 140-220° C.