Stabilization of CO₂‐in‐water emulsions with high internal phase volume using PVAc‐b‐PVP and PVP‐b‐PVAc‐b‐PVP as emulsifying agents

Abstract

Two newly-designed hydrocarbon surfactants, that is, poly(vinyl acetate)-block-poly(1-vinyl-2-pyrrolidone) (PVAc-b-PVP) and PVP-b-PVAc-b-PVP, were synthesized using reversible addition-fragmentation chain transfer polymerization and used to form CO 2 /water (C/W) emulsions with high internal phase volume and good stability against flocculation and coalescence up to 60 h. Their structures were precisely determined by nuclear magnetic resonance, gel permeation chromatography, thermal gravimetric analysis, and differential scanning calorimetry. Besides low temperature and high CO 2 pressure, the surfactant structures were the key factors affecting the formation and stability of high internal phase C/W emulsions, including the polymerization degrees of CO 2 -philic block (PVAc) and hydrophilic block (PVP), as well as the number of hydrophilic tail. The surface tension of the surfactant aqueous solution and the apparent viscosity of the C/W emulsions were also measured to characterize the surfactants efficiency and effectiveness. The surfactants with double hydrophilic tails showed stronger emulsifying ability than those with single hydrophilic tail. The great enhancement of the emulsions stability was due to decrease of the interface tension as well as increase of the steric hindrance in the water lamellae, preventing a frequent collision of CO 2 droplets and their fast coalescence. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46351.

Novel Synthesis of CdSe Quantum Dots in a Confined Space by Using a High Internal Phase Emulsion and Their Application in Fluorescent Labeling

“…In addition, the emulsifier plays an important role in the HIPE system, which can reduce the surface tension between the two phases of the emulsion and also contribute to build a stable and adjustable continuous phase . Figure showed the effect of different contents of emulsifier on the fluorescence performance of QDs prepared by HIPE‐SDS.…”

Synthesis of CO2-philic/hydrophilic surfactant with brush structure and its application in preparing monolithic material

“…The emulsi cation ability of PVAc-g-MPEG can be determined by measuring the stability time of HIPEs [14,19] . The experiment result indicate that PVAc-g-MPEG can exhibit excellent emulsi cation ability (Table 1).…”

“…In the preparation of surfactants, some water-soluble substances can be as hydrophilic components, such as poly(ethylene glycol)(PEG), poly(N-vinylpyrrolidone)(PNVP), poly (2-(dimethylamino) ethyl methacrylate) (PDMAEMA), or some ionic groups, etc. These surfactants can be used to prepare the CO 2in-water (C/W) high internal phase emulsion (HIPE) [14][15][16] , water-in-CO 2 emulsion (W/C) [17] or microemulsion [18] . Tan [19] prepared the di or tri-block polymers PVAc-b-PEG and PVAc-b-PEG-b-PVAc from PVAc and PEG, and the surfactant can show remarkable emulsi cation performance to emulsify up to 97% (v/v, C/W).…”

“…Tan [19] prepared the di or tri-block polymers PVAc-b-PEG and PVAc-b-PEG-b-PVAc from PVAc and PEG, and the surfactant can show remarkable emulsi cation performance to emulsify up to 97% (v/v, C/W). Liu [14] synthesized poly(vinyl acetate)-co-poly(N-vinylpyrrolidone), and it can emulsify the CO 2 /H 2 O system up to 90% (v/v, C/W). In our previous research, we synthesized a cationic amphiphilic surfactant poly(vinyl acetate)-b-poly(dimethylaminoethyl methacrylate) through the method of successive RAFT and ATRP, and the polymers obtained as surfactants can also emulsify the CO 2 /acrylamide solution (AM) system up to 90% (v/v, C/W).…”