Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (2): 322-328.doi: 10.3866/PKU.WHXB201412012

• SOFT MATTER • Previous Articles     Next Articles

Effect of Hydrophobic Chain Length on the Interfacial Dilational Rheological Properties of Polyoxyethylene Sorbitan Fatty Acid Ester

LI Ming1,2, CAO Chong1, XIONG Ke-Jie1, DU Feng-Pei1   

  1. 1. Department of Applied Chemistry, College of Science, China Agriculture University, Beijing 100193, P. R. China;
    2. Research Center of Pesticide Application, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, P. R. China
  • Received:2014-09-16 Revised:2014-12-01 Published:2015-01-26
  • Contact: DU Feng-Pei
  • Supported by:

    The project was supported by the Special Fund for Agroscientific Research in the Public Interest of China (201103024).


The dilational rheological properties of a series of polyoxyethylene sorbitan fatty acid surfactants (TweenX) at the decane/water interface have been investigated using the drop shape analysis method. The experiment results showed that larger quantities of the Tween20 molecules with shorter hydrophobic chain lengths were adsorbed at the interface because they could arrange more closely. Tween40 and Tween60 molecules had similar“actual cross-sectional areas”, which meant that their interfacial tensions were also similar at the critical micelle concentration (γcmc). Furthermore, when the bulk concentration exceeded the critical micelle concentration (cmc), the modulus and elasticity of Tween20 were larger than those of Tween40 and Tween60. When the hydrophobic alkyl chain of TweenX reached a certain length, the interfacial film properties of TweenX affected by the hydrophobic chain length decreased, which led to similar dilational parameters.

Key words: Polyoxyethylene sorbitan fatty acid ester, Hydrophobic chain length, Interface, Dilational modulus, Phase angle