In one example, the polyamine polyether has the structure of (3), where R3 and R5 are the same linear, branched, or cyclic radicals having at least about 10 carbon atoms, such as at least about 18 carbon atoms, or at least about 30 carbon atoms, and y and z are zero, so that the generic structure becomes R1HN???[R3???O]x???R3???NHR2, where R1 to R3 are as described above.