The present invention relates to compositions of spherical microparticles composed of a wall material and at least one cavity that comprises a gas and/or a liquid, which have pores on the surface thereof, wherein the spherical microparticles have a mean particle diameter of 10-600 μm and wherein at least 80% of those microparticles, the particle diameter of which does not deviate from the mean particle diameter of the microparticles of the composition by more than 20%, each have on average at least 10 pores, the diameter of which is in the range from 1/5000 to ⅕ of the mean particle diameter, and, furthermore, the diameter of each of these pores is at least 20 nm,wherein the wall material consists of a composition comprising at least one aliphatic-aromatic polyester, and the wall material has a solubility at 25° C. of at least 50 g/l in dichloromethane, a method for the preparation thereof and also the use thereof.