Fatty acid derivatives of the formula (I) wherein R1 is an aliphatic group containing 1 to 17 carbon atoms, which is linear, branched, saturated or unsaturated； R2, R3, R4, R5, R6, R7 are, independently, hydrogen, methyl, ethyl or hydroxymethyl； m, n and p are numbers from 0 to 17, with the proviso that m + n + p =1, and m + n + p <； 18 where the different monomers can be arranged in statistical order, alternatingly or as a block copolymer and m, n and p can be a statistical mixture； X is, independently, a covalent bond or hydroxy methylene； R8 is an aliphatic group containing 1 to 10 carbon atoms, which is linear, branched, cyclic, saturated or unsaturated, substituted or unsubstituted phenyl or substituted or unsubstituted benzyl, are useful as herbicides.
