SYNTHESIS AND PROPERTIES OF DI-N-DODECYL ALPHA,OMEGA-ALKYL BISPHOSPHATE SURFACTANTS

Three gemini and two bolaform bisphosphate surfactants of the type 12- s-12, with s = 6, 8, 12, 18, and 24 carbon atoms, have been synthesize d and their aggregation behavior has been studied. The bolaform surfac tants 12-18-12 and 12-24-12 were found to form vesicles in aqueous sol ution, as indicated by electron microscopy. The geminis 12-6-12, 12-8- 12, and 12-12-12 form micellar structures. The cmc's of the geminis, o btained from conductivity measurements, spectroscopic methods, and mic rocalorimetry, are very low, on the order of 10(-4) to 10(-5) M. The c me decreases with increasing spacer length. For the bolaform amphiphil es 12-18-12 and 12-24-12 noncooperative phase transitions are detected using fluorescence depolarization and DSC. NMR line-broadening studie s display unusual behavior. The spacer within the 12-24-12 vesicles ha s been found to be membrane spanning, as confirmed by X-ray powder dif fraction.