Soybean-Oil-Based CO2-Switchable Surfactants with Multiple Heads.

Huiyu Huang,Xiaoling Huang,Xin Su,Hongping Quan

doi:10.3390/molecules26144342

Huiyu Huang, Xiaoling Huang + Show 2 more

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https://doi.org/10.3390/molecules26144342

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Abstract

Oligomeric surfactants display the novel properties of low surface activity, low critical micellar concentration and enhanced viscosity, but no CO2 switchable oligomeric surfactants have been developed so far. The introduction of CO2 can convert tertiary amine reversibly to quaternary ammonium salt, which causes switchable surface activity. In this study, epoxidized soybean oil was selected as a raw material to synthesize a CO2-responsive oligomeric surfactant. After addition and removal of CO2, the conductivity analyzing proves that the oligomeric surfactant had a good response to CO2 stimulation. The viscosity of the oligomeric surfactant solution increased obviously after sparging CO2, but returned to its initial low viscosity in the absence of CO2. This work is expected to open a new window for the study of bio-based CO2-stimulated oligomeric surfactants.

Highlights

Traditional surfactants are composed of hydrophilic and hydrophobic groups
Due to the separation caused by the electric repulsion among the ionic head groups or the hydration effect of the ionic groups [1,2], it is difficult for these groups to arrange closely at the interface or in the molecular aggregates, resulting in the relatively low surface activity of the surfactants [3]
The pKaH values of oligomeric surfactant were obtained by theoretical calculation [25] and determined to be from 8.37 and 9.84

Summary

Introduction

Traditional surfactants are composed of hydrophilic and hydrophobic groups. due to the separation caused by the electric repulsion among the ionic head groups or the hydration effect of the ionic groups [1,2], it is difficult for these groups to arrange closely at the interface or in the molecular aggregates, resulting in the relatively low surface activity of the surfactants [3]. Despite the optimal solubility-enhancing properties, thickening behavior, dispersibility and flocculability possessed by the polymeric surfactants, it is generally difficult to realize a directional arrangement of the polymeric surfactant molecules at the interface [3]. Their surface tension is observed to be weaker than the traditional surfactants [4,5]. The advent of oligomeric surfactants has bridged the gap between the two surfactant types. Due to their various characteristics, such as high efficiency, multifunctionality and environmental friendliness, the oligomeric surfactants have recently emerged as new generation surfactants and are most likely to find a widespread use [6,7,8,9]

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