A synthetic polymer has a water-soluble or water-swellable polymer backbone and terminal groups and/or intermediate groups of blocks of hydrophobes of alkyl- or aryl compounds containing a polymerizable cyclic monomer or a polymerizable double bond (or alkene) group or derivatives thereof. The blocks of hydrophobes are composed of two or more units of the same or different hydrophobes. These synthetic polymers are used as rheology modifiers, especially in latex paints.