Dilational rheological properties of novel zwitterionic surfactants containing benzene ring and polyoxyethylene group at water-decane interface

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• 作者：Linfang Dong ; Xulong Cao ; Zhenquan Li ; Lei Zhang ; Zhicheng Xu ; Lu Zhang ; Sui Zhao
• 关键词：Zwitterionic surfactant ; Interface ; Dilational rheology ; Dilational modulus ; Dilational phase angle ; Static modulus
• 刊名：Colloids and Surfaces A: Physicochemical and Engineering Aspects
• 出版年：5 March, 2014
• 年：2014
• 卷：444
• 期：Complete
• 页码：257-268
• 全文大小：1699 K

文摘

The interfacial dilational rheological behaviors of four zwitterionic surfactants with benzene ring and polyoxyethylene group, p-(n-lauryl)-benzyl polyoxyethylene ether carboxybetaine C₁₂BE_xCB (x = 0, 1, 2, 3), were investigated via the drop shape analysis method. The influences of time, oscillating frequency and bulk concentration on dilational properties were explored. The experimental results show that the number of ethylene oxide groups is one of the principal factors to control the interfacial film. The dilational properties of C₁₂BE_xCB are quite different from those of common surfactants: the phase angle decreases with aging time, the slope of the log蔚 鈭?#xA0;log蠅 curve and phase angle of C₁₂BE_xCB decrease in a wide concentration range, and the dilational modulus of C₁₂BE_xCB passes through a plateau value with the increasing concentration for surfactant with more ethylene oxide groups. These phenomena become more and more apparent with increasing ethylene oxide groups and it cannot be attributed to the diffusion-exchange process between the bulk and the interface. It is reasonable to consider that ethylene oxide groups are flexible and can be compressed and expanded, just like a spring. The compression and expansion of the ethylene oxide groups in the interfacial layer and the exchange between interface and sub-layer play a crucial role for C₁₂BE_xCB. Possible schematic diagrams of adsorbed molecules with time and concentration at the water-decane interface are proposed. The results of static modulus measurements and dynamic interfacial viscoelasticity for C_yBE₂CB (y = 8, 10, 12) with different length of hydrophobic chain can support our provided mechanism strongly.