The synergistic effect on surface tension reduction and micelle format
ion was systematically studied for the binary mixtures of sodium dodec
yl sulfate (SDDS) and dodecyl trimethyl ammonium chloride (DDTMAC), Si
gnificant synergism of this system results in large negative values of
parameters beta(sigma) and beta(m) that measure the extent of the int
eraction between the two surfactants for mixed monolayer formation at
aqueous solution/air interface and mixed micelle formation, respective
ly. The stoichiometry and equilibrium constant of the ion - pair compl
ex formation between oppositely charged organic ions were also determi
ned by means of the conductimetric method, Synergism affects through t
he formation of the equimolecular complex can then be verified.