CO2-responsive aqueous foams stabilized by pseudogemini surfactants

Zengzi Wang; Gaihuan Ren; Jiawen Yang; Zhenghe Xu; Dejun Sun

doi:10.1016/j.jcis.2018.10.040

CO₂-responsive aqueous foams stabilized by pseudogemini surfactants

J Colloid Interface Sci. 2019 Feb 15:536:381-388. doi: 10.1016/j.jcis.2018.10.040. Epub 2018 Oct 16.

Authors

Zengzi Wang¹, Gaihuan Ren¹, Jiawen Yang¹, Zhenghe Xu², Dejun Sun³

Affiliations

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.

PMID: 30380437
DOI: 10.1016/j.jcis.2018.10.040

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.

Keywords: CO(2) responsive foam; Long chain fatty acids; Polyetheramine; Pseudogemini surfactants.