The present invention relates to novel comb polymers, to a process for their manufacture and to the use thereof in the stabilization in an aqueous phase of active or effect substances which are insoluble or sparingly soluble in water. The invention furthermore relates to the use of the comb polymers in the manufacture of active substance formulations or active substance preparations of water-insoluble active or effect substances, in particular of active substances for plant protection. The comb polymers can be obtained by copolymerization of monoethylenically unsaturated monomers M, the monomers M comprising: a) at least one monoethylenically unsaturated monomer Ma chosen from esters of monoethylenically unsaturated C3-C8-monocarboxylic acids with C1-C20-alkanols, C5-C10-cycloalkanols, phenyl-C1-C4-alkanols or phenoxy-C1-C4-alkanols and the diesters of monoethylenically unsaturated C4-C8-dicarboxylic acids with C1-C20-alkanols, C5-C10-cycloalkanols, phenyl-C1-C4-alkanols or phenoxy-C1-C4-alkanols; and b) at least one monoethylenically unsaturated monomer Mb chosen from the esters of monoethylenically unsaturated C3-C8-monocarboxylic acids and the mono- and diesters of monoethylenically unsaturated C4-C8-dicarboxylic acids with poly(C2-C4-alkylene ether)ols; and the total amount of the monomers Ma and Mb making up at least 60% by weight of the monomers M constituting the comb polymer.