Stabilized All-Aqueous Emulsions via Electrospraying
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Solution Overview
Problem
Existing methods for producing all-aqueous emulsions with high viscosity (≥ 100 mPa·s) and ultra-low interfacial tension face challenges in achieving stability and monodispersity, particularly in systems with dynamic viscosity of 100 mPa·s or above, where traditional methods like microfluidics and perturbation approaches result in polydisperse droplets and short-term stability due to coalescence.
Innovation Solution
The method involves electrospraying a first electrically charged aqueous phase containing a solute with a second aqueous phase containing oppositely charged surfactants, inducing electrostatic forces that form droplets with a membrane to prevent coalescence and leakage, using incompatible solutes like PEG and dextran to create stable, monodisperse emulsions with high viscosity and ultra-low interfacial tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional microfluidic methods are used to produce all-aqueous emulsions, then droplet formation is achieved, but the emulsions become polydisperse and unstable due to low interfacial tension and coalescence
Solution Approach 1:
The patent introduces a third phase (oil phase) as an intermediary between the two aqueous phases. This oil phase acts as a stabilizing medium that prevents direct contact and coalescence between the immiscible aqueous phases, thereby maintaining emulsion stability and monodispersity despite the low interfacial tension between water and water phases
Solution Approach 2:
The patent changes the interfacial tension parameter by introducing surfactants at the water-oil and oil-water interfaces. This parameter modification enables stable droplet formation and prevents coalescence, resolving the contradiction between achieving droplet formation and maintaining emulsion stability
2Speed
If perturbation methods are used to induce jet breakup in viscous systems, then droplet formation is achieved, but the growth rate of Rayleigh-Plateau instability is insufficient and emulsions are only stable for short periods
Solution Approach 1:
The oil phase serves as a mediator that enables rapid and stable droplet formation. By facilitating controlled jet breakup and providing a stabilizing interface, the oil phase allows for both fast droplet generation and long-term emulsion stability, overcoming the limitations of direct water-water perturbation methods
Solution Approach 2:
The patent replaces the mechanical perturbation approach with an electrostatic field-based method. High voltage application induces rapid charge accumulation and Coulomb explosion, substituting the slow mechanical Rayleigh-Plateau instability with a faster electrostatic-driven breakup mechanism that achieves both speed and stability
3Manufacturing precision
If electrospraying is used to produce all-aqueous emulsions, then monodisperse droplets are formed, but coalescence still occurs without additional stabilization mechanisms
Solution Approach 1:
The oil phase acts as a protective intermediary layer between the charged aqueous droplets. This intermediate phase prevents direct coalescence of droplets by providing a physical barrier, thereby maintaining both the monodispersity achieved through electrospraying and the long-term stability of the emulsion system
Solution Approach 2:
The oil phase forms a flexible interfacial film around the aqueous droplets. This thin film provides mechanical protection against coalescence while allowing the droplets to maintain their electrosprayed monodisperse structure, effectively combining precision droplet formation with enhanced stability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach produces stable all-aqueous emulsions with enhanced monodispersity and extended stability, preventing coalescence and leakage of encapsulated agents, suitable for drug delivery, materials fabrication, and biomedical applications without the use of organic solvents.
Implementation Method 1
The method involves electrospraying a first electrically charged aqueous phase containing a solute with a second aqueous phase containing oppositely charged surfactants, inducing electrostatic forces that form droplets with a membrane to prevent coalescence and leakage
Implementation Method 2
electrospraying at least one first liquid substance by applying an electrical potential to said first liquid substance, creating a charged electrosprayed product
Implementation Method 3
Aqueous two-phase systems (ATPSs), or all-aqueous emulsions, are formed by dissolving two incompatible solutes in water above the critical concentrations for phase separation. These incompatible solutes can redistribute in water and form immiscible aqueous phases
Implementation Method 4
at least one surfactant, at least 2.25% by weight, relative to the total weight of the composition, of at least one water-soluble salt
Data Source
Figure 1(a)~2
AI summary
Methods for preparing all-aqueous emulsions, including stable emulsions and/or emulsions having high viscosity and/or ultra-low interfacial tension are described. The method includes mixing, combining, or contacting a first electrically charged phase containing a first solute with at least a second phase containing a second solute. The solutes are incompatible with each other. The electrostatic forces between the two phases induce the formation of droplets of a dispersed phase in a continuous phase. The dispersed and continuous phases contain oppositely charged molecules, which stabilize the drops of the dispersed phase.