The invention relates to a macroporous plastics bead material with an average particle diameter from 10 to 1000 μm, containing a copolymer of a) 5-60 wt. % vinylically polymerizable monomers with a water solubility of at least 1% at 20° C., b) 1-40 wt. % vinylically polymerizable monomers with an additional functional group, which can enter into covalent bonds with the nucleophilic groups of the ligands in a polymer-like reaction, c) 10-40 wt. % hydrophilic, crosslinking radical-polymerizable monomers with two or more ethylenically unsaturated polymerizable groups and d) 10-60 wt. % vinylically polymerizable monomers with a water solubility of at most 1% at 20° C. are contained, as a rule with the monomers a) to d) adding up to 100%.