Quaternary ammonium amphiphiles of the following structures were synthesized: Cn-BB-N+3C1 and Cn-BB-Cm- N+3C1, where C., and Cm are hydrocarbon chains of n = 0, 4, 7, 12 and m = 4, 10, and BB and N+3C1 denote 4,4'-diphenylazomethine moiety and trimethylammonium group, respectively. These amphiphiles gave clear or slightly turbid solutions when dispersed in water by the sonication or injection method. The aqueous solutions contained extraordinarily large aggregates: 106- 107 daltons except for BB-N+3C1 and C4-BB-N+3C1, as estimated by the light scattering method. The critical micelle concentration was 10-4-10-5 M when the hydrocarbon tail (Cn portion) was present. Electron microscopy indicated that these aggregates (n = 7 and 10) possessed lamellar or vesicle structures which were composed of the bilayer assembly (layer thickness 40-60 Å). The bilayer structure could not be detected for amphiphiles of n = 0 and 4. The Cm portion did not appear to affect the aggregate structure. NMR spectroscopy and differential scanning calorimetry suggested the liquid crystalline property of these aqueous aggregates. In conclusion, the stable bilayer assembly similar to that of biomembranes was prepared in dilute aqueous solution from single-chain ammonium amphiphiles which possessed a rigid segment.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry