Patent ID: 8163682

Claim:
A polymer, comprising: 50-100% by weight, based on the weight of the polymer, of repeat units which are derived from one or more ethylenically unsaturated ester compounds of the formula (I) in which R is hydrogen or methyl, R 1 is a linear or branched alkyl radical having from 7 to 30 carbon atoms, R 2 and R 3 are each independently hydrogen or a group of the formula —COOR′ in which R′ is hydrogen or an alkyl group having from 7 to 30 carbon atoms, wherein the polymer is a star polymer having from 3 to 21 arms and at least 3 of the arms comprise at least 40% by weight, based on the weight of the arms, of repeat units which derive from one or more ethylenically unsaturated ester compounds of the formula (I) in which R is hydrogen or methyl, R 1 is a linear or branched alkyl radical having from 7 to 30 carbon atoms, R 2 and R 3 are each independently hydrogen or a group of the formula —COOR′ in which R′ is hydrogen or an alkyl group having from 7 to 30 carbon atoms; wherein the polymer is prepared by controlled polymerization proceeding from a polyfunctional initiator; wherein the number of polymer arms depends on the number of functionalities of the initiator; wherein the center of the star polymer has at most 50 carbon atoms; wherein the star polymer has a polydispersity M w /M n in the range from 1.0 to 2.0; and wherein the polymer has from 0.1 to 40% by weight of repeat units which are derived from one or more ethylenically unsaturated ester compounds of the formula (II) in which R is hydrogen or methyl, R 4 is a linear or branched alkyl radical having from 1 to 6 carbon atoms, R 5 and R 6 are each independently hydrogen or a group of the formula —COOR″ in which R″ is hydrogen or an alkyl group having from 1 to 6 carbon atoms.