ARCHAEBACTERIAL LIPIDS : HIGH SURFACE ACTIVITY OF POLYISOPRENOID SURFACTANTS IN WATER

Abstract The surface tension of aqueous solutions of the amphiphiles, (3RS, 7R, 11R)-3,7,11,15-tetramethylhexadecyl-X where X is SO 4 − Na + , PO 4 H − Na + , N + (CH 3 ) 3 Br − , N + (C 2 H 5 ) 3 Br − , etc., was studied at 25–75°C. The polyisoprenoid surfactants provided the surface tension of 26–31 mN m −1 , which was lower by 10–15 mN m −1 than that of corresponding straight chain-analogues. The results were discussed in conjunction with an unordered fluid state of the highly branched hydrocarbon chains at an air-water interface.