Dissolution dynamics of a binary switchable hydrophilicity solvent–polymer drop into an acidic aqueous phase

Billet, Romain; Zeng, Binglin; Lockhart, James; Gattrell, Mike; Zhao, Hongying; Zhang, Xuehua

doi:10.1039/d2sm01275h

Cited by 4 publications

(7 citation statements)

References 48 publications

(73 reference statements)

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“…This phase separation behavior has been observed at room temperature in previous work 37 . Similarly, water droplets are observed following the shrinking interface of the drop.…”

Section: Resultssupporting

confidence: 85%

“…This phase separation behavior has been observed at room temperature in previous work. 37 Similarly, water droplets are observed following the shrinking interface of the drop. At the end of the dissolution process, the increase of the viscosity of the drop fixes the water droplets that remain trapped in the particle.…”

Section: Resultsmentioning

confidence: 95%

“…The fraction of water contained in dissolving DMCHA drops could be much higher than the solubility of water in DMCHA (~21 wt% at 20°C 36 ), as a large number of dispersed microdroplets were present in the DMCHA-PS drops. 37 Recent research showed that the solubility of a compound in a drop may be markedly different from the solubility in the bulk, when a phase separation process or chemical reactions in the drops may lead to a large change in the concentration of the compound in the small drops. 38,39 Moreover, for water microdroplets to escape from the dissolving drop and merge into the surrounding liquid phase, their transport through the interface has to take place, which may be hindered by high viscosity near the interface by accumulated PS.…”

Section: Resultsmentioning

confidence: 99%

“…The fraction of water contained in dissolving DMCHA drops could be much higher than the solubility of water in DMCHA (~21 wt% at

20

°C 36 ), as a large number of dispersed microdroplets were present in the DMCHA‐PS drops 37 . Recent research showed that the solubility of a compound in a drop may be markedly different from the solubility in the bulk, when a phase separation process or chemical reactions in the drops may lead to a large change in the concentration of the compound in the small drops 38,39 .…”

Section: Resultsmentioning

confidence: 99%

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Hydrophilic solvent recovery from switched‐on microdroplet dissolution

Billet,

Zeng,

et al. 2023

Droplet

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Switchable hydrophilicity solvents (SHSs) are a unique class of chemical compounds that can be switched between their hydrophobic and hydrophilic forms. The switchable characteristics allow SHSs to be used as emerging, green solvents for sustainable extraction and separation technology. In the production of polymeric microparticles from recycled plastics, SHSs are used to dissolve the polymer and then are switched to the hydrophilic form for separation from the generated polymeric microparticles. However, it is extremely difficult to fully recover the SHS residue from the mixtures. In this work, we will identify the key parameters that determine the level of the solvent residue during the switched‐on dissolution of emulsion microdroplets. The SHS N,N‐dimethylcyclohexylamine from solvent–polymer binary emulsion droplets was switched to the hydrophilic, water‐soluble form, triggered by addition of an acid in the surrounding aqueous phase. By applying a sensitive detection method developed in this work, we compared the levels of SHS residue in polymer microparticles obtained under 30 different dynamical and chemical conditions for the switching processes. The quantitative analysis revealed that residue levels remained constant at varied addition rates and concentration of the trigger solution, but decreased with the increase in organic phase fractions or the decrease in the emulsion temperature. Trapped water in the drops during switched‐on dissolution may have contributed to the high level of solvent residue. The understanding of the new possible mechanism for residual solvent reported in this work may help develop effective approaches for the recovery of switchable solvents in environmentally friendly separation processes.

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“…This phase separation behavior has been observed at room temperature in previous work 37 . Similarly, water droplets are observed following the shrinking interface of the drop.…”

Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

“…The fraction of water contained in dissolving DMCHA drops could be much higher than the solubility of water in DMCHA (~21 wt% at

20

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Hydrophilic solvent recovery from switched‐on microdroplet dissolution

Billet,

Zeng,

et al. 2023

Droplet

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“…The formation of internal microdroplets within the host drop may bear a resemblance to liquid-liquid phase separation in multicomponent drops. [16,25,38] Typically, the preferential dissolution of a drop component leads to the composition change in the drop and a reduced solubility of another component in the drop. Encapsulated microdroplets form from liquid-liquid phase separation in response to the reduced miscibility of the drop components.…”

Section: Dynamics Of Internal Water Microdropletsmentioning

confidence: 99%

Launching a Drop via Interplay of Buoyancy and Stick‐Jump Dissolution

Zeng,

Yang,

et al. 2023

Small

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According to Archimedes' principle, a submerged object with a density lower than that of aqueous acid solution is more buoyant than a smaller one. In this work, a remarkable phenomenon is reported wherein a dissolving drop on a substrate rises in the water only after it has diminished to a much smaller size, though the buoyancy is smaller. The drop consisting of a polymer solution reacts with the acid in the surrounding, yielding a water‐soluble product. During drop dissolution, water‐rich microdroplets form within the drop, merging with the external aqueous phase along the drop‐substrate boundary. Two key elements determine the drop rise dynamics. The first is the stick‐jump behavior during drop dissolution. The second is that buoyancy exerts a strong enough force on the drop at an Archimedean number greater than 1, while the stick‐jump behavior is ongoing. The time of the drop rise is controlled by the initial size and the reaction rate of the drop. This novel mechanism for programmable drop rise may be beneficial for many future applications, such as microfluidics, microrobotics, and device engineering where the spontaneous drop detachment may be utilized to trigger a cascade of events in a dense medium.

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Introduction, Types, Properties, and Applications of Switchable Solvents: A Review

Kanawade,

Kesarwani,

Bajpai Tripathy

et al. 2024

ChemistrySelect

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Switchable solvents (SS) are a class of liquids with the unique ability to significantly alter their physical properties in response to external stimuli such as changes in temperature or the introduction or removal of CO2 gas. This reversible behaviour allows them to return to their original state with minimal changes, making them highly advantageous for various applications. A notable example of a switchable solvent is waste carbon dioxide gas, which is non‐toxic, non‐flammable, and cost‐effective. The versatility of switchable solvents extends to their polarity and physical states, which can be modified through molecular adjustments, opening new pathways for research and industrial applications. This review provides a comprehensive overview of switchable solvents, including their classification, history, properties, and applications, with a particular focus on their role in green chemistry. The types of switchable solvents discussed include Switchable‐Polarity Solvents (SPS), Switchable‐Hydrophilicity Solvents (SHS), and Switchable Water. Each type is examined in terms of synthesis, chemical properties, and development. The desirable properties of switchable solvents, such as their efficiency and recyclability, make them suitable alternatives to traditional solvents in various fields. Their applications range from water treatment and oil extraction to cleaning solid particles and recovering residual motor oil. Additionally, switchable solvents have proven effective as reaction media and in recovering polystyrene from foam. This paper also highlights the environmental benefits of switchable solvents, emphasizing their role in reducing the ecological impact of chemical processes. The potential for future developments in this field is significant, with ongoing research aimed at enhancing their performance and expanding their applications. By providing a detailed analysis of switchable solvents, this review aims to support researchers and industry professionals in developing more sustainable and efficient chemical processes.

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Dissolution dynamics of a binary switchable hydrophilicity solvent–polymer drop into an acidic aqueous phase

Abstract: Switchable hydrophilicity solvents (SHSs) are solvents defined by their ability to switch from their hydrophobic form to a hydrophilic form when put in contact with an acidic trigger such as...

Cited by 4 publications

References 48 publications

Hydrophilic solvent recovery from switched‐on microdroplet dissolution

Hydrophilic solvent recovery from switched‐on microdroplet dissolution

Launching a Drop via Interplay of Buoyancy and Stick‐Jump Dissolution

Introduction, Types, Properties, and Applications of Switchable Solvents: A Review

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