A review of high internal phase Pickering emulsions: Stabilization, rheology, and 3D printing application

He, Xiao; Lu, Qingye

doi:10.1016/j.cis.2024.103086

Cited by 23 publications

(2 citation statements)

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“…7 As a functionalized printing ink with excellent colloidal stability against coalescence, Pickering emulsions have recently attracted significant interest in 3D-printing applications, as they can endure repeated mechanical deformation and rising temper- ature during the direct-ink-write (DIW) printing process, attaining improved printability and shape fidelity. 8 Although stable to coalescence and Ostwald ripening, Pickering emulsion systems are prone to flocculation, which is a universal phenomenon affecting the physical stability, flow behavior, and structure of such emulsions. 9 Often the dispersed droplets in the O/W emulsions are present in the form of small/large clusters ("flocs"), more prevalent in Pickering emulsions that contain a high-volume fraction of the dispersed phase, also known as Pickering-high-internal-phase emulsions (Pickering-HIPEs).…”

Section: Introductionmentioning

confidence: 99%

Depletion Flocculation of High Internal Phase Pickering Emulsion Inks: A Colloidal Engineering Approach to Develop 3D Printed Porous Scaffolds with Tunable Bioactive Delivery

Shahbazi,

Jäger,

Huc-Mathis

et al. 2024

ACS Appl. Mater. Interfaces

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Flocculation is a type of aggregation where the surfaces of approaching droplets are still at distances no closer than a few nanometers while still remaining in close proximity. In a high internal-phase oil-in-water (O/W) emulsion, the state of flocculation affects the bulk flow behavior and viscoelasticity, which can consequently control the three-dimensional (3D)-printing process and printing performance. Herein, we present the assembly of O/W Pickering high-internal-phase emulsions (Pickering-HIPEs) as printing inks and demonstrate how depletion flocculation in such Pickering-HIPE inks can be used as a facile colloidal engineering approach to tailor a porous 3D structure suitable for drug delivery. Pickering-HIPEs were prepared using different levels of cellulose nanocrystals (CNCs), co-stabilized using “raw” submicrometer-sized sustainable particles from a biomass-processing byproduct. In the presence of this sustainable particle, the higher CNC contents facilitated particle-induced depletion flocculation, which led to the formation of a mechanically robust gel-like ink system. Nonetheless, the presence of adsorbed particles on the surface of droplets ensured their stability against coalescence, even in such a highly aggregated system. The gel structures resulting from the depletion phenomenon enabled the creation of high-performance printed objects with tunable porosity, which can be precisely controlled at two distinct levels: first, by introducing voids within the internal structure of filaments, and second, by generating cavities (pore structures) through the elimination of the water phase. In addition to printing efficacy, the HIPEs could be applied for curcumin delivery, and in vitro release kinetics demonstrated that the porous 3D scaffolds engineered for the first time using depletion-flocculated HIPE inks played an important role in 3D scaffold disintegration and curcumin release. Thus, this study offers a unique colloidal engineering approach of using depletion flocculation to template 3D printing of sustainable inks to generate next-generation porous scaffolds for personalized drug deliveries.

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Section: Introductionmentioning

confidence: 99%

Depletion Flocculation of High Internal Phase Pickering Emulsion Inks: A Colloidal Engineering Approach to Develop 3D Printed Porous Scaffolds with Tunable Bioactive Delivery

Shahbazi,

Jäger,

Huc-Mathis

et al. 2024

ACS Appl. Mater. Interfaces

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“…High internal phase emulsion (HIPE), an emulsion containing internal phase of >74% dispersed as individual droplets, has been known for many years and has found applications in fields such as food, fuels, oil recovery, biphasic interfacial catalysis, and cosmetics. − In the past 20 years, a growing interest focuses on its application in materials science, i.e., as template to fabricate highly porous structure (so-called HIPE-templating technique). ,− HIPE is commonly stabilized by high content of nonionic surfactant (5–50%, relative to its continuous phase) owing to its high volume ratio of disperse phase/continuous phase. − When the HIPE contains monomers in its continuous phase, polymerization of the monomers and removal of the dispersed phase could cause a highly open-cell foam, named polyHIPE. − The HIPE-templating technique provides the advantages of generating porous materials with a diverse morphology, for example, polymer foams, membranes, beads, or rods. Since the structure of polyHIPE replicates from its precursor HIPE-template, by tuning the droplet size and the chemical nature of HIPE phases, polyHIPEs with designed performance can be fabricated. − Moreover, in situ or postpolymerization approaches can be also adapted to tune the surface area or endow polyHIPE with additional chemical properties. − PolyHIPEs could be used in a wide range of areas, including energy storage applications, , tissue engineering, chromatography, separation, , microreactors, , sound absorption, , and catalysis. − The implementation of these applications largely depends on their highly open-cellular structure, i.e., the presence of interconnected pores (also named pore throats or windows) between adjacent voids.…”

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confidence: 99%

Mechanism of Interconnected Pore Formation in High Internal Phase Emulsion-Templated Polymer

Zhang,

Chen,

You

et al. 2024

ACS Macro Lett.

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High internal phase emulsion-templated polymer, named polyHIPE, has received widespread attention due to its great potential applications in many fields, such as separation, adsorption, heterogeneous catalysis, and sound absorption. The broad applicability is largely dependent on its adjustable opening structure. However, the question of why polyHIPE has an interconnected pore network structure is still to be discussed. Herein, different types (w/o, o/w, and o/o) of HIPEs are prepared and subsequently detected with laser scanning confocal microscopy (LSCM), and the polyHIPEs obtained by curing the HIPEs are characterized by SEM. The observations suggest that the interconnected pore formation is primarily due to the presence of the surfactant-rich phase in the film between the neighboring droplets in HIPE. The interconnected pores are generated by removal of the surfactant-rich domains in the postcuring procedure, and their sizes would be enlarged if the solubility of the surfactant in the continuous phase decreases in the curing stage.

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Assessing rheological properties of oxidized Moringa oleifera gum and carboxymethyl chitosan‐based self‐healing hydrogel for additive manufacturing applications

Verma,

Kumar,

Pradhan

et al. 2024

Polymer Engineering & Sci

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Rheology plays a vital role in pneumatic three‐dimensional (3D) printing of hydrogels. This study investigates the rheological behavior of a novel self‐healing hydrogel (O‐MOG/CMCh) formed by a Schiff base crosslinking reaction between oxidized Moringa oleifera gum (O‐MOG), a biodegradable antimicrobial polysaccharide, and carboxymethyl chitosan (CMCh), a water‐soluble biocompatible chitosan derivative. Three hydrogel formulations were designed using 5% w/v of CMCh with varied concentrations of O‐MOG (3% w/v, 4% w/v, and 5% w/v) and evaluated through rheology analyses, including frequency sweeps, amplitude sweeps, oscillatory thixotropy, and gelation kinetics. These tests revealed that the material has shear thinning, self‐healing properties, a high linear viscoelastic region (LVE), and gel formation times (tgel) of 3.23–4.57 min. The hydrogel synthesized with 5% w/v of O‐MOG composition exhibited the best characteristics for printability based on rheological assessments, and this composition was used for further printing assessment, where bi‐layered 4 × 4 and 2 × 2 grids were successfully printed using 22 G (0.41 mm) and 23 G (0.34 mm) syringes. All the constructs had a printability index value of 1 ± 0.13 and spreading ratios <6.5, demonstrating the feasibility of employing the synthesized hydrogel as an acellular matrix via additive manufacturing.Highlights Self‐healing hydrogel was prepared by mixing the precursors through a cannula. Rheology was examined using standard tests for printability assessment. 3D printability was achieved using two different gauze syringes. Printability parameters were recorded and analyzed for the constructs.

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A review of high internal phase Pickering emulsions: Stabilization, rheology, and 3D printing application

Cited by 23 publications

References 233 publications

Depletion Flocculation of High Internal Phase Pickering Emulsion Inks: A Colloidal Engineering Approach to Develop 3D Printed Porous Scaffolds with Tunable Bioactive Delivery

Depletion Flocculation of High Internal Phase Pickering Emulsion Inks: A Colloidal Engineering Approach to Develop 3D Printed Porous Scaffolds with Tunable Bioactive Delivery

Mechanism of Interconnected Pore Formation in High Internal Phase Emulsion-Templated Polymer

Assessing rheological properties of oxidized Moringa oleifera gum and carboxymethyl chitosan‐based self‐healing hydrogel for additive manufacturing applications

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