Abstract
The effect of the short non-ionic amphiphiles: n-alc. (n = 3-6), polypropylene glycol alkyl ether (CnPOm, for n = 3, 4; m = 1-3) and polyethylene glycol (CnEOm, for n = 3; m = 1 and n = 4; m = 1-3) on the crit. micellar concn. (CMC) of SDS in aq. solns. at 25° was detd. exptl. by measuring the elec. conductance. There is a linear relation between the no. of propylene glycol and ethylene glycol ...
Abstract
The effect of the short non-ionic amphiphiles: n-alc. (n = 3-6), polypropylene glycol alkyl ether (CnPOm, for n = 3, 4; m = 1-3) and polyethylene glycol (CnEOm, for n = 3; m = 1 and n = 4; m = 1-3) on the crit. micellar concn. (CMC) of SDS in aq. solns. at 25° was detd. exptl. by measuring the elec. conductance. There is a linear relation between the no. of propylene glycol and ethylene glycol groups and the slope of the CMC decrease with amphiphile concn. The propylene glycol group appears to be more efficient in lowering the CMC than the ethylene glycol group which is less hydrophobic. Considering the polypropylene glycol alkyl ethers as the condensation of an n-alc. and a certain no. of propylene glycol groups it was possible to classify these amphiphiles according to their efficiency to decrease the CMC of SDS: C4PO3 > C6PO0 > C4PO2 > C3PO3 > C4PO1 > C3PO2 > C5PO0 > C3PO1 > C4PO0 > C3PO0. This trend is different from the series of hydrophobicity of these compds., inferred recently from water/CnPOm binary phase diagrams: C6PO0 > C5PO0 > C4PO4 > C4PO3 > C4PO1 > C4PO0 > C3PO3 > C3PO2 > C3PO1 > C3PO0. The hydrophobicity of these compds. increases much more with the addn. of 1 C in the alkyl chain than with the addn. of one propylene glycol group. The co-surfactant behavior of some of these mols. is also discussed and compared in terms of the topol. of their ternary phase diagrams SDS/water/co-surfactant. Some striking differences in the co-surfactant behavior of the studied amphiphiles are found between their CMC decrease property and the topol. of their corresponding ternary systems.
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