The invention relates to a substrate comprising a surface at least partially coated with an oil repellent, characterized in that the oil repellent comprises at least one compound in the form of a
copolymer comprising M units and N units linked by covalent bonds on its backbone, where M, N, R1 and R2 are the same or different and are H, C1-C10
alkyl or C2-C10 alkenyl; x and Y are the same or different and are spacer arms formed by heteroatoms or linear or branched
hydrocarbon chains containing at least one
heteroatom and at least one
carbon atom; b is the same or different and is a polyether group; l is the same or different and is a halogenated C1-C6
carbon group or a halogenated
ether group shown in the formula (I), and in the formula (I), Q is a
halogen atom; p, identical or different, is a linear or branched C1-C10
alkyl group or C2-C10 alkenyl group comprising at least one
halogen atom; p is selected from 1 to 4; and n is selected from 1 to 20, and wherein the
copolymer is
water soluble. The invention also relates to a method for oil-proof
coating of such a substrate, and to a timepiece or jewelry comprising an
assembly containing such a substrate.