SYNTHESIS AND AGGREGATION PROPERTIES OF A NEW FAMILY OF AMPHIPHILES WITH AN UNUSUAL HEADGROUP TOPOLOGY

A new family of amphiphiles, derived from a rigid dicarboxylic acid headgroup unit of unusual topology, has been synthesized. The aggregation of these molecules in aqueous solution has been examined by H-1 NMR and dye solubilization methods. Two modes of aggregation appear to be operative within this group of amphiphiles, one determined by the headgroup and the other determined by the flexible tail. The former mode is dominant when the tail is short or nonexistent, and the latter is dominant when the tail contains six or more nonpolar atoms. The latter mode appears to be a typical micellization process, but the former is less cooperative. For the latter group of amphiphiles, comparison with literature data for a family of long chain alkyl malonate surfactants indicates that the wide, rigid headgroup, containing 16 non-carboxylate carbon atoms, has the equivalent ''hydrophobic impact'' on aggregation of only five CH2 groups in the flexible tail.