A polyether having a functional group that is reactive to isocyanate with at least one polyisocyanate, which has an average isocyanate functionality in the range of 2.4 to 3.5, and at least one vinyl compound, which has a functional group that is reactive to isocyanate, wherein the molar ratio of polyether to vinyl compound lies in the range of 3:1 to 1:3 and the ratio of the sum of the molar quantities of polyether and vinyl compounds to isocyanate groups lies in the range of 1.5:1 to U.5. Corresponding vinylterminated prepolymers have the advantage of low visocity together with good water solubility and therefore can be used advantageously for applications as injection agents.
