Surfactant-Free Microemulsion Based on CO₂-Induced Ionic Liquids

Abstract

A novel surfactant-free microemulsion (SFME) based on CO2-induced ionic liquids (ILs) was prepared. Among them, dipropylamine (DPA) was directly reacted with CO2 to form the ILs that were composed of the ammonium salts and the ammonium carbamate salts, which was confirmed by 13C NMR, Fourier transform infrared, electrical conductivity, and pH. In addition, the purity of ILs was determined by 1H NMR. We used water as a polar phase, ILs as an amphi-solvent, and 1-dodecanol as a nonpolar phase to prepare SFME. The multiphase zone and the single-phase zone of the SFME were obtained from the ternary-phase diagram. Then, the microstructure of the studied SFME was determined to be the O/W type by the staining method. The demulsification process of SFME was explored by means of conductivity, pH, dynamic light scattering, and gas chromatography. Under the introduction of N2, CO2 could be removed, and the ILs could be reversibly restored to DPA, resulting in a change in polarity, which caused most of DPA to transfer into the oil phase, eventually leading to demulsification.

Production of 4-Ethylphenol from Lignin Depolymerization in a Novel Surfactant-Free Microemulsion Reactor

“…Due to the fact that acidic ILs are widely applied in the depolymerization of biomass with well activity and endowed with the feature of surfactivity in nature, the influence of different acidic ILs on lignin depolymerization in a typical microemulsion system (point d in Figure ) was investigated. From Figure B, it can be found that the catalytic performance of [C 3 H 6 SO 3 HMIm]­[HSO 4 ] (93.5 mg g –1 ) is better than those of [C 4 H 8 SO 3 HMIm]­[Cl] and [C 4 H 8 SO 3 HMIm]­[HSO 4 ] (55.6 and 68.1 mg g –1 respectively), and [HOOCMMIm]­[Cl] also shows a better catalytic activity than [HOOCEMIm]­[Cl] (60.0 and 51.7 mg g –1 , respectively).…”

“…Due to the fact that acidic ILs are widely applied in the depolymerization of biomass with well activity 37 and endowed with the feature of surfactivity in nature, 38 the influence of different acidic ILs on lignin depolymerization in a typical microemulsion system (point d in Figure 1) was investigated.…”

“…Besides, due to the stronger Broǹsted acidity (Figure S4 and Table S4), SO 3 H-functionalized ILs provide better yields of phenolic monomers than those with a carboxyl group, and this observation is similar to that of our previous study. 37 For comparison, the catalytical efficiency of H 2 SO 4 is also determined (68.1 mg g −1 ) and found to be less than that of SO 3 H-functionalized ILs but better than that of ILs with a carboxyl group.…”

pH-Responsive Non-Pickering Emulsion Stabilized by Dynamic Covalent Bond Surfactants and Nano-SiO2 Particles

“…Prior to this, many researchers have introduced various stimulus responses into the emulsion (such as temperature response, − magnetic response, , redox response, , light response, , CO 2 response, − pH response, , etc.) in an attempt to make the stability and demulsification of the emulsion controllable.…”

Enhancing Poly(lactic acid) Microcellular Foams by Formation of Distinctive Crystalline Structures

“…At present, some methods have been proposed to improve the foaming behavior of PLA, such as chain extension, chain branching, and blending with other materials. − Moreover, controlling crystallization kinetics of PLA during foaming has also been recognized as an effective way to improve its foaming behavior. Li et al reported a new supercritical fluid foaming process based on preisothermal cold crystallization for PLA, and foams with high expansion ratio were obtained .…”