Abstract:

The effects of NaBr on the properties of heterogemini surfactant CmOhpNC8(m:10, 14, 16) in aqueous solution were investigated by means of surface tension and fluorescence probe techniques. The results show that NaBr strongly promoted the adsorption and the aggregation of CmOhpNC8 at the air/water interface in aqueous bulk solution. The c20 was reduced to extremely low order of magnitude of micromole per liter at c(NaBr)≥10 mol/L, showing quite a high efficiency in surface tension reduction. Upon NaBr addition, CmOhpNC8 exhibited strong premicellization in aqueous bulk solution. So low c20 and evident premicellization could not be observed in the equal-mole mixture of the corresponding conventional surfactants, exhibiting the surface-active advantage as well as the salt-sensitivity of heterogemini-type surfactant, in which a short spacer was introduced to link the two different headgroups.

Key words: heterogemini surfactant CmOhpNC8, NaBr, aqueous solution surface tension, premicellization