Surfactant-Free Double Emulsion via Catastrophic Inversion
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Solution Overview
Problem
Existing methods for manufacturing water-in-oil-in-water double emulsions require surfactants, leading to environmental issues, high energy costs, and low encapsulation efficiency, especially for hydrophilic active agents, due to phase instability and osmotic pressure challenges.
Innovation Solution
A one-step method involving the addition of an aqueous phase to an oil phase with controlled adhesion energy and viscosity ratios, without surfactants, to create a stable water-in-oil-in-water double emulsion, allowing for high encapsulation efficiency of hydrophilic active agents by achieving catastrophic inversion and subsequent crosslinking of oligomers or monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If surfactants are used to stabilize emulsions, then emulsion stability is improved, but environmental harm and contamination increase
Solution Approach 1:
The invention removes surfactants from the emulsion system entirely, extracting the harmful stabilizing agent while maintaining emulsion stability through alternative means (phase inversion mechanism). This eliminates environmental contamination and harmful effects of surfactants while preserving the desired emulsion properties.
Solution Approach 2:
The invention introduces a specific oil phase composition as an intermediary that enables stable double emulsion formation without surfactants. The oil phase acts as a mediator between the aqueous phases, facilitating catastrophic inversion and stable W/O/W structure formation through its specific interfacial properties.
2Stability of the object's composition
If traditional two-step emulsion methods are used, then emulsion formation is achieved, but process complexity and energy consumption increase
Solution Approach 1:
The invention merges the emulsion formation steps into a single catastrophic inversion process. Instead of separately forming primary emulsion then secondary emulsion, the method combines both emulsion formation events into one continuous addition process, dramatically simplifying the工艺流程 and reducing energy consumption.
Solution Approach 2:
The invention performs preliminary preparation of the oil phase with specific composition and properties before the emulsion process. This pre-conditioning of the oil phase enables the catastrophic inversion to occur naturally during aqueous phase addition, eliminating the need for complex subsequent processing steps.
3Quantity of substance
If conventional emulsion techniques are used, then encapsulation is achieved, but encapsulation efficiency for hydrophilic agents remains low
Solution Approach 1:
The invention inverts the traditional emulsion approach by using catastrophic inversion from W/O to W/O/W structure. This inversion mechanism creates a concentrated inner aqueous phase that effectively traps hydrophilic agents, reversing the usual dispersion problem and achieving high encapsulation efficiency for water-soluble substances.
Solution Approach 2:
The invention changes key parameters including oil phase composition, viscosity ratio, and interfacial tension to enable catastrophic inversion. These parameter modifications create optimal conditions for hydrophilic agent encapsulation, transforming the system from one that disperses hydrophilic agents to one that concentrates and retains them in the inner aqueous phase.
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 method achieves remarkably stable and concentrated emulsions with over 50% encapsulation of hydrophilic active agents, avoiding surfactant-related issues and energy-intensive processes, while ensuring long-term stability and efficient encapsulation.
Implementation Method 1
the adhesion energy between two droplets of aqueous phase dispersed in the oil phase ranges from 10-5 to 10-3 J.m-2
Implementation Method 2
a water-in-oil-in-water double emulsion, comprising two aqueous phases and one oil phase, wherein one of the two aqueous phases is entrapped in the oil phase and the second aqueous phase entraps the oil phase
Implementation Method 3
concentrated to a limit fraction φmax, they invert according to a specific scheme where the initial W/O single emulsion gives rise to a W/O/W double emulsion
Implementation Method 4
crosslinking the oligomers and/or monomers of the oil phase
Implementation Method 5
the oil phase comprises at least one compound selected from oligomers, monomers and mixtures thereof
Implementation Method 6
the ratio between the dynamic viscosity of the innermost aqueous phase and the viscosity of the oil phase ranges from 0.01 to 20
Implementation Method 7
at least 50% w/w of active agent relative to the total weight of the emulsion are encapsulated with the method according to the invention
Implementation Method 8
the hydrophilic active tends to disperse in the continuous phase rather than being encapsulated by the oligomeric phase, due to osmotic pressure between the innermost aqueous phase and the external aqueous phase
Data Source
Figure 1a)~2
Figure 3
Figure 4a)~4c)
AI summary
The present invention relates to a method for the manufacture of a water-in-oil-in-water double emulsion comprising a step of adding dropwise an aqueous phase to an oil phase until a catastrophic inversion. The present invention also relates to a water-in-oil-in-water double emulsion, a method for preparing solid microcapsules and solid microcapsules.