Three homologous anionic AE₃3SO₃[C_nH_2n+1(OE)₃SO₃Na(n=12, 14, 16)] surfactants were synthesized and purified. Firstly, their critical micelle concentration (cmc) predictions were done on an optimum Quantitative Structure-Property Relationship (QSPR) model created previously, and the cmc values were experimentally measured by use of surface tension method. It can be concluded that the QSPR model is valid due to the good agreement between the calculated results and the experimental data. Secondly, it should be emphasized that the EO segment within AESO₃ moiety possesses both hydrophilicity and hydrophobicity. On one hand, from QSPR calculation, Klevens equation and organic concept diagram, the EO segment in AESO₃ moiety exhibits hydrophobicity in micellization. Moreover, with increase in alkyl chain length from 12 to 16 for AE 3SO₃, the hydrophobicity of EO chain is on a par with that of 2.4, 2.3 and 2.2 CH₂ groups respectively. On the other hand, the calculation of the thermodynamic parameters shows that the introduction of the first EO into the dodecyl sulfonate decreases ΔG°_mic by about 3 kJ/mol, the same as one CH₂ group does. The introduction of the second and the third EO, however, decreases ΔG°_mic by about 1 kJ/mol respectively, which reflects that with increase in EO chain the hydrophilicity of the EO unit gets increased.

Key words: sulfonated polyoxyethylene(3)alcohol, critical micelle concentration(cmc), quantitative structure-property relationship(QSPR), hydrophilicity2hydrophobicity of oxyethylene