Hongyao Yin1, Yujun Feng2, Peixun Li3, James Doutch3, Yixiu Han4, Yongjun Mei4. 1. Polymer Research Institute, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, PR China. 2. Polymer Research Institute, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, PR China. Electronic address: yjfeng@scu.edu.cn. 3. ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, OXON OX11 0QX, UK. 4. The Second Research Institute of Civil Aviation Administration of China (CAAC), Chengdu 610041, PR China.
Abstract
HYPOTHESIS: Current viscoelastic surfactant (VES) aqueous solutions quickly freeze and thus, lose their viscoelasticity and flowability at subzero temperatures, limiting their practical use in cold environments. Therefore, it is highly desirable to develop cryo-VES fluids with freezing point far below 0 °C. Since addition of alcohol antifreeze greatly reduces the freezing point of water, cryo-VES fluids might be generated in the presence of alcohols. EXPERIMENTS: The self-assembly behavior of a C22-tailed surfactant, erucyl dimethyl amidopropyl betaine (EDAB), in eight alcohol/water cosolvents from 20 to -20 °C was studied by pyrene fluorescent probe, cryo-TEM imaging and cryo-SNAS characterization, and the solution properties of the mixtures were investigated by rheological test. FINDINGS: It is found that the alcohol molecular structure, content and temperature play crucial roles dominating EDAB self-assembly behavior. Monohydric alcohols are unfavorable for micelles formation and growth, thus VES fluids cannot be obtained in the presence of 50 vol% monohydric alcohols even at subfreezing temperatures. On the contrary, dihydric and trihydric alcohols with short alkyl chain show less negative effect on EDAB micellization. Thus, cryo-VES fluids can be formed in the presence of 50 vol% ethylene glycol, 1,3-propanediol or glycerol due to the formation of wormlike micelles. These cryo-VES fluids with different alcohols exhibit different temperature-sensitivity and rheological properties, furnishing them with potential applications in anti-freeze hydraulic fracking fluids and aircraft deicing/anti-icing fluids.
HYPOTHESIS: Current viscoelastic surfactant (VES) aqueous solutions quickly freeze and thus, lose their viscoelasticity and flowability at subzero temperatures, limiting their practical use in cold environments. Therefore, it is highly desirable to develop cryo-VES fluids with freezing point far below 0 °C. Since addition of alcohol antifreeze greatly reduces the freezing point of water, cryo-VES fluids might be generated in the presence of alcohols. EXPERIMENTS: The self-assembly behavior of a C22-tailed surfactant, erucyl dimethyl amidopropyl betaine (EDAB), in eight alcohol/water cosolvents from 20 to -20 °C was studied by pyrene fluorescent probe, cryo-TEM imaging and cryo-SNAS characterization, and the solution properties of the mixtures were investigated by rheological test. FINDINGS: It is found that the alcohol molecular structure, content and temperature play crucial roles dominating EDAB self-assembly behavior. Monohydric alcohols are unfavorable for micelles formation and growth, thus VES fluids cannot be obtained in the presence of 50 vol% monohydric alcohols even at subfreezing temperatures. On the contrary, dihydric and trihydric alcohols with short alkyl chain show less negative effect on EDAB micellization. Thus, cryo-VES fluids can be formed in the presence of 50 vol% ethylene glycol, 1,3-propanediol or glycerol due to the formation of wormlike micelles. These cryo-VES fluids with different alcohols exhibit different temperature-sensitivity and rheological properties, furnishing them with potential applications in anti-freeze hydraulic fracking fluids and aircraft deicing/anti-icing fluids.