)k -- and --(CH2)k SO2 N(R')(CH2)k --, where R' is hydrogen, a phenyl group or is a methyl or ethyl group and where each k is independently an integer from 1 to about 20; p is 2 or more, up to the valency of A; R is a hydrogen atom or is a substituted or unsubstituted alkyl group; and A is the residue of a dimer acid, representing an aliphatic moiety containing from about 30 to 170 carbon atoms. 1