The instant invention relates to new compounds of the formula I R1 and R2 are each independently of the other a fluorine containing group, R3 and R4 are each independently of the other hydrogen, a fluorine containing group, C1-C12alkyl, phenyl or R4, together with the carbon atom to which they are bonded, form a C5-C8-cycloalkylidene ring that is unsubstituted or substituted by from 1 to 3 C1-C4alkyl groups; R5, R6, R7 and R8 are each independently of the other hydrogen, C1-C12alkyl or C3-C12alkenyl, X1 and X2 are each independently of the other a direct bond or C1-C12alkylene, m is 1 to 10,000, and n is 0 to 10,000. These new compounds of the formula I are useful as reducers of surface energy for organic materials such as polycarbonates, polyesters or polyketones or their mixtures, blends or alloys. Polymers with such a reduced surface energy possess an “easy to clean”, “self-cleaning” “antisoiling”, “soil-release” “antigraffiti”, “oil resistance”, “solvent resistance”, “chemical resistance”, “self lubricating”, “scratch resistance”, “low moisture absorption” and “hydrophobic” surface.