MICELLIZATION OF 2 TRIQUATERNARY AMMONIUM SURFACTANTS IN AQUEOUS-SOLUTION

As part of our current studies of oligomeric amphiphiles, two trimeric surfactants containing three dodecyl chains and three quaternary ammo nium headgroups connected by 1,3-propanediyl groups, the decylbis[3-(d imethyldodecylammonio)propyl]ammonium tribromide and trichloride, refe rred to as 12-3-12-3-12,3Br(-) and 12-3-12-3-12,3Cl(-) have been synth esized and purified, and their micellization behavior has been investi gated in aqueous solution. On a weight/volume basis, the cmc's of the trimeric surfactants are well below those of the corresponding monomer ic and dimeric surfactants (dodecyltrimethylammonium bromide, or DTAB, and 1,3-bis(dodecyldimethylammonio)propane dibromide or 12-3-12,2Br(- )), whereas the micelle ionization degrees of the monomeric, dimeric, and trimeric surfactants are rather close. At a given concentration (w eight/volume basis), the solution of 12-3-12-3-12,3Br(-) is much more viscous than that of the corresponding monomeric and dimeric surfactan ts, indicating a much stronger tendency to micelle growth. Measurement s of micelle aggregation numbers at low surfactant concentrations supp orted this conclusion.