Disclosed is a method for producing polymer foams from reactive polycondensation resins with a maximum pore diameter of 1 mu m. Said method comprises the steps of: 1) producing a gelable mixture of the reactive polycondensation resin in a solvent or dispersing agent; 2) producing an aqueous dispersion containing polymer particles; 3) mixing the mixture obtained in step 1) with the dispersion obtained in step 2), whereby a hydrated gel is obtained; and 4) drying the hydrated gel so as to obtain the polymer foam. The drying process in step 4) takes place at a pressure and a temperature that lie below the critical pressure and below the critical temperature of the liquid phase of the gel while the gel is not brought in contact with an organic liquid in order to replace the water contained in the gel by said liquid following step 3) and prior to step 4). |