Coacervated Capsule Leakage Control via Humectant Slurry
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Solution Overview
Problem
Capsules made by complex coacervation often experience leakage of encapsulated materials due to concentration gradients, leading to stability issues, particularly in dentifrice compositions where it is desirable to reduce leakage and enhance capsule stability.
Innovation Solution
Incorporating coacervated capsules in a slurry with at least 10 wt % humectant, such as sorbitol or glycerin, to reduce the leakage of capsule contents, with the humectant concentration affecting the water activity and thereby controlling the leakage rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If coacervated capsules are supplied in an aqueous slurry, then the capsules are easy to handle and process, but the encapsulated materials diffuse out through the pores into the liquid phase due to concentration gradient
Solution Approach 1:
The patent introduces an osmotic agent (such as sodium chloride, potassium chloride, or other inorganic salts) as an intermediary substance in the aqueous slurry. This osmotic agent mediates the interaction between the capsule interior and exterior by creating an osmotic pressure gradient that counteracts the concentration gradient driving leakage. The osmotic agent acts as a mediator that modifies the chemical potential difference across the capsule wall, thereby reducing material diffusion while maintaining the capsules in a processable aqueous slurry form.
Solution Approach 2:
The patent changes the chemical parameters of the aqueous slurry by adding osmotic agents that alter the osmotic pressure and ionic strength of the medium. This parameter change affects the thermodynamic driving force for material diffusion across the capsule wall. By adjusting the concentration and type of osmotic agent, the system modifies the chemical potential gradient to minimize leakage while preserving capsule integrity and processability.
2Speed
If the concentration gradient is high, then the driving force for material release is increased, but the leakage rate increases leading to loss of encapsulated materials
Solution Approach 1:
The osmotic agent serves as a mediator that modulates the concentration gradient effect. By introducing ions that can penetrate or interact with the capsule wall, the osmotic agent creates a counterbalancing osmotic pressure that reduces the net driving force for unwanted leakage. This intermediary mechanism allows controlled release when desired while preventing premature loss of encapsulated materials.
Solution Approach 2:
The patent modifies the chemical potential parameters of the system by adding osmotic agents. This changes the thermodynamic driving force equation, where the effective concentration gradient becomes the difference between the encapsulated material concentration and the osmotic agent-induced counter-pressure. By adjusting osmotic agent concentration, the system optimizes the balance between controlled release and leakage prevention.
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
The use of a high humectant concentration in the capsule slurry significantly reduces the leakage rate of the encapsulated contents, maintaining stability and effectiveness in dentifrice compositions across various temperatures.
Implementation Method 1
Incorporating coacervated capsules in a slurry with at least 10 wt % humectant, such as sorbitol or glycerin, to reduce the leakage of capsule contents, with the humectant concentration affecting the water activity and thereby controlling the leakage rate
Implementation Method 2
Encapsulated materials can diffuse out the capsule shell through the pores of the capsules into the liquid phase due to the concentration gradient
Data Source
AI summary
A capsule slurry including at least one coacervated capsule and at least 10 wt % humectant is disclosed. The humectant may be sorbitol, glycerin, polyethylene glycol, propylene glycol, xylitol, erythritol and/or betaine.