Zengzi Wang1, Gaihuan Ren1, Jiawen Yang1, Zhenghe Xu2, Dejun Sun3. 1. Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, Shandong 250100, PR China. 2. Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong 518055, PR China; Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada. 3. Key Laboratory of Colloid and Interface Chemistry, Shandong University, Ministry of Education, Jinan, Shandong 250100, PR China. Electronic address: djsun@sdu.edu.cn.
Abstract
HYPOTHESIS: To obtain surfactants with superior surface activity and responsive behavior, "pseudogemini" surfactants (short for D-LCFA) are synthesized by mixing long chain fatty acids (LCFA) and polyetheramine D 230 at fixed molar ratio (2:1). Non-covalently bonded building blocks indicate that CO2-responsive aqueous foams can be obtained by utilizing such pseudogemini surfactants. EXPERIMENTS: 1H NMR and FT-IR characterizations prove that the building blocks of these surfactants are associated by electrostatic interaction. The synthesis (Brønsted acid-base reaction) is simple and eco-friendly. "Pseudogemini" structure enables D-LCFA to reduce surface tension of aqueous solution effectively, thus facilitating foam generation. Rheograms, FF-TEM and Cryo-TEM results prove that different aggregates in D-LCFA aqueous solutions lead to different foam properties. FINDINGS: Bubbling of CO2 for about 30 s leads to the rupture of aqueous foams generated by D-LCFA, while removing CO2 by bubbling of N2 at 65 °C for 10 min enables re-generation of foams. The CO2-responsive foaming properties can be attributed to dissociation of D-LCFA upon bubbling of CO2 and re-association upon removal of CO2. The effective CO2-responsive foams can be applied to many areas, such as foam fracturing, foam enhanced oil recovery or recovering of radioactive materials.
HYPOTHESIS: To obtain surfactants with superior surface activity and responsive behavior, "pseudogemini" surfactants (short for D-LCFA) are synthesized by mixing long chain fatty acids (LCFA) and polyetheramine D 230 at fixed molar ratio (2:1). Non-covalently bonded building blocks indicate that CO2-responsive aqueous foams can be obtained by utilizing such pseudogemini surfactants. EXPERIMENTS: 1H NMR and FT-IR characterizations prove that the building blocks of these surfactants are associated by electrostatic interaction. The synthesis (Brønsted acid-base reaction) is simple and eco-friendly. "Pseudogemini" structure enables D-LCFA to reduce surface tension of aqueous solution effectively, thus facilitating foam generation. Rheograms, FF-TEM and Cryo-TEM results prove that different aggregates in D-LCFA aqueous solutions lead to different foam properties. FINDINGS: Bubbling of CO2 for about 30 s leads to the rupture of aqueous foams generated by D-LCFA, while removing CO2 by bubbling of N2 at 65 °C for 10 min enables re-generation of foams. The CO2-responsive foaming properties can be attributed to dissociation of D-LCFA upon bubbling of CO2 and re-association upon removal of CO2. The effective CO2-responsive foams can be applied to many areas, such as foam fracturing, foam enhanced oil recovery or recovering of radioactive materials.
Authors: Martin Reifarth; Marek Bekir; Alain M Bapolisi; Evgenii Titov; Fabian Nußhardt; Julius Nowaczyk; Dmitry Grigoriev; Anjali Sharma; Peter Saalfrank; Svetlana Santer; Matthias Hartlieb; Alexander Böker Journal: Angew Chem Int Ed Engl Date: 2022-03-23 Impact factor: 16.823