Abstract
Vesicle forming ability of double-chain cationic surfactants {dialkyldimethyl-ammonium bromides {(CnH2n+1)2(CH3)2N+Br-; DDAB (n=12), DTDAB (n=14), DHDAB (n=16), DODAB (n=18)} in deep sea water was examined, and the effect of their chain length on the membrane properties and dispersability of vesicles formed was investigated. Any of the surfactants failed to form vesicles in 100% of deep sea water while they formed vesicles in a mixture of deep sea water (5%)/purified water water (95%) and in deep sea water treated with reverse osmosis membrane (RO water). The particle size of vesicles was found to increase with the chain length of the cationic surfactants (except for DHDAB). For DTDAB with 14 carbon atoms in the alkyl chain, vesicles in RO water were more stable than in purified water, being stable for six months after preparation. The experimental findings demonstrated that the stability of the vesicles depended on the preparation temperature and the gel-liquid crystal phase transition temperature of the surfactants (in each system).
