The present invention relates to the use of end groups Y, where Y stands for (formula I), where Rf stands for CF3—(CH2)r—, CF3—(CH2)r—O—, CF3—(CH2)r—S—, CF3CF2—S—, SF5—(CH2)r—, [CF3—(CH2)r]2N—, [CF3—(CH2)r]NH— or (CF3)2N—(CH2)r—, B stands for a single bond, O, NH, NR, CH2, C(O)—O, C(O), S, CH2—O, O—C(O), N—C(O), C(O)—N, O—C(O)—N, N—C(O)—N, O—SO2 or SO2—O, R stands for alkyl having 1 to 4 C atoms, b stands for 0 or 1 and c stands for 0 or 1, q stands for 0 or 1, where at least one radical from b and q stands for 1, and r stands for 0, 1, 2, 3, 4 or 5, as end group in surface-active compounds, to corresponding novel compounds, and to processes for the preparation of these compounds.