wherein R??? is chosen from a hydrogen atom and CH3, B is an ethylenoxy group, n is an integer ranging from 0 to 100, R is a hydrocarbon-based group chosen from alkyl, arylalkyl, aryl, alkylaryl and cycloalkyl radicals comprising from 8 to 30 carbon atoms, for example from 10 to 24 carbon atoms such as from 12 to 18 carbon atoms.