Abstract: Disclosed herein are graft polymers, their preparation, and methods of using graft polymers, where the graft polymers include as polymer backbone (A) a polyalkylene oxide ester polymer with a weight average molecular weight Mw of 500 to 50 000 g/mol and a polydispersity PD of 2 to 6, including 10 to 560 ether groups and 2 to 51 ester groups, which are interconnected with alkylene groups, which is significantly more biodegradable than conventional polyalkylene oxide polymers, and polymeric side chains grafted onto the polymer backbone A, where the polymeric sidechains (B) are obtainable by polymerization of at least one monomer being selected from i) at least one vinyl ester monomer (B1) and ii) optionally at least one further olefinically unsaturated monomer (B2) polymerizable with monomer B1.