Recent progress in emulsion gels: from fundamentals to applications

Wan, Chuchu; Cheng, Qing; Zeng, Min; Huang, Caili

doi:10.1039/d2sm01481e

Cited by 14 publications

(12 citation statements)

References 130 publications

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“…The behaviors of emulsion gels has been reviewed by Wan et al and may serve as a supplement to this review. [31] Alternative approaches to generating responsive emulsions include the use of small-molecule surfactants and particles as "Pickering" emulsifiers, which have been reviewed by Brown et al [32] and Tang et al [20] The current review focuses on polymeric surfactants; for a broader overview of the literature on responsive emulsions, readers are directed other recent reviews. [33,34]…”

Section: Introductionmentioning

confidence: 99%

Stimuli‐Responsive Polymers for Engineered Emulsions

Rajbanshi,

Hilton,

Dreiss

et al. 2024

Macromol. Rapid Commun.

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Emulsions are complex. Dispersing two immiscible phases, thus expanding an interface, requires effort to achieve and the resultant dispersion is thermodynamically unstable, driving the system toward coalescence. Furthermore, physical instabilities, including creaming, arise due to presence of dispersed droplets of different densities to a continuous phase. Emulsions allow the formulation of oils, can act as vehicles to solubilize both hydrophilic and lipophilic molecules, and can be tailored to desirable rheological profiles, including “gel‐like” behavior and shear thinning. The usefulness of emulsions can be further expanded by imparting stimuli‐responsive or “smart” behaviors by inclusion of a stimuli‐responsive emulsifier, polymer or surfactant. This enables manipulation like gelation, breaking, or aggregation, by external triggers such as pH, temperature, or salt concentration changes. This platform generates functional materials for pharmaceuticals, cosmetics, oil recovery, and colloid engineering, combining both smart behaviors and intrinsic benefit of emulsions. However, with increased functionality comes greater complexity. This review focuses on the use of stimuli‐responsive polymers for the generation of smart emulsions, motivated by the great adaptability of polymers for this application and their efficacy as steric stabilizers. Stimuli‐responsive emulsions are described according to the trigger used to provide the reader with an overview of progress in this field.

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Section: Introductionmentioning

confidence: 99%

Stimuli‐Responsive Polymers for Engineered Emulsions

Rajbanshi,

Hilton,

Dreiss

et al. 2024

Macromol. Rapid Commun.

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“…Emulsions, as a typical polydisperse system formed by dispersing a liquid into another immiscible one in droplet forms, have been extensively applied in many industrial processes and commercial products, such as foods, pharmaceuticals, cosmetics, and personal care products . To address the thermodynamically instability due to large interface energy between immiscible liquids, emulsifiers were widely adopted, including surfactants or surface-active polymers, categorized as traditional emulsifiers. , Key questions regarding traditional emulsions mainly involves three aspects: (i) the toxicity of chemically synthesized surfactants; (ii) the disposal difficulty of adsorbed and enriched surfactants at interphases; and (iii) the unexpected effect incurred by the self-recovery of assembled surfactant film. − Developing novel emulsions of low traditional emulsifier dosage with new functions such as stimulus-responsiveness is of vital importance and also challenging.…”

Section: Introductionmentioning

confidence: 99%

pH/Ion Dual-Responsive Emulsion Via a Cationic Surfactant and Positively Charged Magnesium Hydroxide Nanosheets

Zhu,

Chen,

Ding

et al. 2024

Langmuir

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Emulsions, formed by dispersing a liquid into another immiscible one by virtue of emulsifiers, have been widely applied in commercial applications like foods, pharmaceuticals, cosmetics, and personal care, which always confront environmental and/or toxic questions due to emulsifiers’ high dosage. Recently, a study on Pickering emulsions points out a solution to stable emulsions based on the costabilizing effect of colloidal particles, which focused on surface-active particles cooperating with oppositely charged ionic surfactants. Costabilized emulsions adopting a charge-similar ionic surfactant and particles were less studied. In this article, a hexane-in-water emulsion was prepared in use of a cationic surfactant cetyltrimethylammonium bromide (CTAB) with positively charged magnesium hydroxide (MH) nanosheets at low concentrations (10–5 M and 10–2 wt %, respectively). The emulsion is stable due to the synergy by CTAB and MH nanosheets, which functions in virtue of the electric repulsion by similarly charged particles, the mechanical shielding by MH nanosheets, and restrained water drainage in lamellae between droplets due to the gelation of MH nanosheets. Moreover, the emulsion is doubly switchable within emulsification/demulsification via convenient pH or ion manipulation, a mechanism based on the breakdown and rebuilding of the costabilizing synergy. Such dual-responsive emulsions show high potential for the delicate control of drug delivery, release, and biphasic biocatalysis applications.

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“…1,2 Emulsion gels exhibit outstanding physical stability as a result of combining the characteristics of both emulsions and hydrogels, 3 and display lots of advantageous characteristics (including rheology and texture) for use in food structuring and fat mimetics, 4 as well as for improving the stability, delivery and controlled release of bioactive compounds. [5][6][7] The gel-like properties originate from the high concentration of closely packed oil droplets with strong interactions or the entangled network of the biopolymers in the continuous phase. 8 Emulsion gels are often constructed using a variety of natural polymers (such as proteins and polysaccharides) due to their excellent functional properties, especially emulsifying, stabilizing and gelling properties.…”

Section: Introductionmentioning

confidence: 99%