Abstract:We have developed a new benign means of reversibly breaking emulsions and latexes by using "switchable water", an aqueous solution of switchable ionic strength. The conventional surfactant sodium dodecyl sulfate (SDS) is not normally stimuli-responsive when CO2 is used as the stimulus but becomes CO2 -responsive or "switchable" in the presence of a switchable water additive. In particular, changes in the air/water surface tension and oil/water interfacial tension can be triggered by addition and removal of CO2… Show more
“…Replacing them with CO 2 -responsive surfactants could be problematic because of higher surfactant cost and the need to reformulate well-established processes and formulations. 54 Redispersion is achievable using gentle hand shaking rather than sonication (sonication was required for the redispersion of most CO 2switchable latexes reported in this review). Su et al added DMEA as a CO 2 -switchable additive to a dodecane/water emulsion, which had been prepared using SDS surfactant.…”
Section: Co 2 -Switchable Functional Groupsmentioning
confidence: 97%
“…54 The process was reversible and removal of CO 2 resulted into the creation of a stable emulsion (Fig. Replacing them with CO 2 -responsive surfactants could be problematic because of higher surfactant cost and the need to reformulate well-established processes and formulations.…”
Section: Co 2 -Switchable Functional Groupsmentioning
confidence: 99%
“…147,156,182 SHS can be separated from a hydrophobic product by extraction with carbonated water. 54 For instance, when a CO 2 -switchable ionogen is in its neutral form, the ionic strength of the aqueous solution is low, but after the introduction of CO 2 , the ionic strength increases (Fig. 147 SHS can be used in the recycling of polystyrene foam.…”
CO2 is an ideal trigger for switchable or stimuli-responsive materials because it is benign, inexpensive, green, abundant, and does not accumulate in the system. Many different CO2-responsive materials including polymers, latexes, solvents, solutes, gels, surfactants, and catalysts have been prepared. This review focuses on the preparation, self-assembly, and functional applications of CO2-responsive polymers. Detailed discussion is provided on the synthesis of CO2-responsive polymers, in particular using reversible deactivation radical polymerization (RDRP), formerly known as controlled/living radical polymerization (CLRP), a powerful technique for the preparation of well-defined (co)polymers with precise control over molecular weight distribution, chain-end functional groups, and polymer architectural design. Self-assembly in aqueous dispersed media is highlighted as well as emerging potential applications.
“…Replacing them with CO 2 -responsive surfactants could be problematic because of higher surfactant cost and the need to reformulate well-established processes and formulations. 54 Redispersion is achievable using gentle hand shaking rather than sonication (sonication was required for the redispersion of most CO 2switchable latexes reported in this review). Su et al added DMEA as a CO 2 -switchable additive to a dodecane/water emulsion, which had been prepared using SDS surfactant.…”
Section: Co 2 -Switchable Functional Groupsmentioning
confidence: 97%
“…54 The process was reversible and removal of CO 2 resulted into the creation of a stable emulsion (Fig. Replacing them with CO 2 -responsive surfactants could be problematic because of higher surfactant cost and the need to reformulate well-established processes and formulations.…”
Section: Co 2 -Switchable Functional Groupsmentioning
confidence: 99%
“…147,156,182 SHS can be separated from a hydrophobic product by extraction with carbonated water. 54 For instance, when a CO 2 -switchable ionogen is in its neutral form, the ionic strength of the aqueous solution is low, but after the introduction of CO 2 , the ionic strength increases (Fig. 147 SHS can be used in the recycling of polystyrene foam.…”
CO2 is an ideal trigger for switchable or stimuli-responsive materials because it is benign, inexpensive, green, abundant, and does not accumulate in the system. Many different CO2-responsive materials including polymers, latexes, solvents, solutes, gels, surfactants, and catalysts have been prepared. This review focuses on the preparation, self-assembly, and functional applications of CO2-responsive polymers. Detailed discussion is provided on the synthesis of CO2-responsive polymers, in particular using reversible deactivation radical polymerization (RDRP), formerly known as controlled/living radical polymerization (CLRP), a powerful technique for the preparation of well-defined (co)polymers with precise control over molecular weight distribution, chain-end functional groups, and polymer architectural design. Self-assembly in aqueous dispersed media is highlighted as well as emerging potential applications.
“…Particle size and zeta potential measurements Zeta potential and laser particle size analysis measurements are used as an efficient way to detect the molecular morphological changes of molecules [32,33]. Therefore, to investigate the molecule existing form of PolyAspAm(OA/Larg) in aqueous solution and its molecular microstructure variation during the cycle of treatment with CO 2 followed by N 2 , size and zeta potential of the nanoparticles were employed by testing the dispersion via dynamic light scattering (DLS) at 25°C.…”
Section: Measurement Of Swelling Capacitymentioning
Polyaspartamides, which are termed to a variety of amide derivatives of poly(aspartic acid), one of the poly(amino acid)s or polypeptides, have been intensively investigated as biodegradable and biocompatible polymers with a broad range of potential biomedical applications as well as eco-friendly industrial uses. By discovering that polymers containing amidine or guanidine functionality have been shown to be reversibly responsive to carbon dioxide (CO 2 ), we have developed two polyaspartamide systems: novel CO 2 -responsive hydrogel and amphiphilic polyaspartamide derivative containing L-arginine. In this work, poly(2-hydroxyethyl aspartamide) derivative was modified with L-arginine unit (PHEA-Larg), before cross-linked by hexamethylene diisocyanate in the presence of dibutyltin dilaurate catalyst to provide a hydrogel having not only good gel strength, but reversible CO 2 absorption characteristics. On the other hand, amphiphilic polyaspartamide derivative containing hydrophobic long alkyl moiety (octyl) and L-arginine unit was synthesized, and the CO 2 -responsive solubility and molecular self-assembly behaviors of the systems were investigated. These new polyaspartamide systems have potential in several applications including CO 2 capture, CO 2 -responsive and switchable surface, sensor, smart hydrogel for controlled drug delivery system, etc.
“…Addition of CO 2 to a suspension of fine clay particles in SW causes much faster and more complete settling of the particles. 117 SW can be used as a draw solution for the recovery of fresh water from wastewater or sea water using forward osmosis. 117 Emulsions stabilized by non-switchable surfactants in SW can be broken by CO 2 addition.…”
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