Shuo Lu1, Qiliang Mei2, Jiayi Chen1, Zhe Wang1, Wenhong Li2, Chunyan Feng2, Xuefeng Li3, Jinfeng Dong4. 1. Engineering Research Center of Organosilicon Compounds & Materials, Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China. 2. Research Institute of Exploration and Development, PetroChina Changqing Oilfield Company, Xi'an 710018, China. 3. Engineering Research Center of Organosilicon Compounds & Materials, Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China. Electronic address: lixuefeng@whu.edu.cn. 4. Engineering Research Center of Organosilicon Compounds & Materials, Ministry of Education, College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China. Electronic address: jfdong@whu.edu.cn.
Abstract
HYPOTHESIS: Shear-thickening micelles were mostly made of cationic surfactants, but shear-thickening was rarely reported in the zwitterionic/anionic surfactants. Since wormlike micelles were essential in shear-thickening systems, it should be common for the hybrid wormlike micelles formed by zwitterionic/anionic surfactants, and their fundamental features need to be clarified. EXPERIMENTS: The micellization of zwitterionic surfactant homologies alkyl dimethyl amidopropyl hydroxyl sulfobetaine (AHSB) and sodium dodecyl sulfate (SDS) in brine was studied, and various environmental factors were considered systematically. Light scattering, rheology, zeta potential, 1H NMR and cryo-TEM techniques were employed to characterize the AHSB/SDS wormlike micelles. FINDINGS: AHSB/SDS hybrid wormlike micelles were formed in a wide xSDS region to endow them with apparent viscosities, in which the electrostatic and hydrophobic interactions between AHSB and SDS molecules were critical. AHSB with the longer tail, the higher cAHSB and cNaCl were advantageous to enhance the viscosity because of the longitudinal growth of wormlike micelles. The shear-thickening AHSB/SDS samples were commonly composed of unbranched wormlike micelles with various length, and the shear-induced alignment of wormlike micelles was the major cause as verified by cryo-TEM. Moreover, the quantitative relationships on the critical shear rate ɣ̇c were established, and the activation energies were obtained from the temperature-dependent ɣ̇c.
HYPOTHESIS: Shear-thickening micelles were mostly made of cationic surfactants, but shear-thickening was rarely reported in the zwitterionic/anionic surfactants. Since wormlike micelles were essential in shear-thickening systems, it should be common for the hybrid wormlike micelles formed by zwitterionic/anionic surfactants, and their fundamental features need to be clarified. EXPERIMENTS: The micellization of zwitterionic surfactant homologies alkyl dimethyl amidopropyl hydroxyl sulfobetaine (AHSB) and sodium dodecyl sulfate (SDS) in brine was studied, and various environmental factors were considered systematically. Light scattering, rheology, zeta potential, 1H NMR and cryo-TEM techniques were employed to characterize the AHSB/SDS wormlike micelles. FINDINGS: AHSB/SDS hybrid wormlike micelles were formed in a wide xSDS region to endow them with apparent viscosities, in which the electrostatic and hydrophobic interactions between AHSB and SDS molecules were critical. AHSB with the longer tail, the higher cAHSB and cNaCl were advantageous to enhance the viscosity because of the longitudinal growth of wormlike micelles. The shear-thickening AHSB/SDS samples were commonly composed of unbranched wormlike micelles with various length, and the shear-induced alignment of wormlike micelles was the major cause as verified by cryo-TEM. Moreover, the quantitative relationships on the critical shear rate ɣ̇c were established, and the activation energies were obtained from the temperature-dependent ɣ̇c.