at the end can be prepared very simply by means of a one pot reaction first in this reaction a polymethacrylate obtained by free radical polymerization in the presence of a chain regulator is transesterified with u03b1 u03c9 difunctional polyethers at temperatures from about 70 to about 150 u00b0 c preferably from 100 to 120 u00b0 c the reaction can be carried out with or without solvent in general residues of water are first removed from the system with an inert solvent such as toluene or xylene in order to remove any traces of moisture present to simplify the removal from the reaction mixture of the alcohol liberated in the transesterification reaction methanol or butanol for example depending on the polymethacrylate used it is advisable to add an inert solvent such as toluene xylene or a petroleum fraction having a boiling range from about 70 to about 140 u00b0 c prior art lewis transesterification catalysts such as alkyl titanate alkyl zirconate dialkyltin acetate halide or dialkyl tin dialkyl esters can be used in amounts of from about 0 1 to about 3 by weight based on the polymethacrylate particularly suitable catalysts are isopropyl titanate dibutyltin acetate chloride and dibutyltin oxide the molar ratio of polymethacrylate to polyalkylene oxide can be from about 1.