n the range from 1 to 500, for example, from 1 to 100 and from 4 to 25, including all values and subranges there between; X is preferably a linear or branched alkylene chain containing from 1 to 30 carbon atoms and in particular 3 to 10 carbon atoms, and Y is preferably an alkylene chain that is linear or branched or that possibly comprises rings and/or unsaturations, containing from 1 to 40 carbo