Multilayered Core/Shell Microcapsules for Controlled Fragrance Release
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Solution Overview
Problem
Existing microcapsules for encapsulating perfumes in laundry compositions have inadequate barrier and release properties, leading to inefficient perfume delivery and retention on fabrics, with issues of delamination and permeability.
Innovation Solution
A method of creating multilayered microcapsules with a coacervate outer shell and a synthetic polyurea inner shell, formed through complex coacervation and interfacial polymerization processes, which results in a composite structure that provides improved barrier and release properties, maintaining integrity even upon mechanical breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer microcapsule structure is used, then the manufacturing process is simple, but the barrier properties and release control are inadequate
Solution Approach 1:
The capsule shell is segmented into multiple functional layers: an inner coacervate layer providing baseline barrier properties and an outer polymer layer providing enhanced protection and controlled release. This segmentation allows each layer to specialize in specific functions, improving overall reliability without requiring complete redesign of the entire system.
Solution Approach 2:
The invention uses composite shell structure combining coacervate material and synthetic polymer material. The coacervate inner shell provides selective permeability and the outer polymer shell provides mechanical strength and environmental resistance. This composite approach achieves superior barrier properties by leveraging the complementary strengths of different materials.
2Reliability
If a multilayered shell structure is implemented, then barrier properties improve, but the shell may delaminate under mechanical stress
Solution Approach 1:
The inner coacervate shell and outer polymer shell are merged through interfacial polymerization where the polymer forms directly at the interface with the coacervate. This creates a bonded composite structure where the layers are chemically or physically integrated, preventing delamination while maintaining the barrier benefits of multiple layers.
Solution Approach 2:
The capsule employs flexible thin film shells that can accommodate mechanical stress without rigid fracture. The coacervate and polymer layers form a flexible composite that can deform elastically under stress, maintaining integrity and preventing delamination while preserving barrier properties.
3Productivity
If the perfume is released immediately upon capsule rupture, then delivery efficiency is high, but the active lifetime is reduced
Solution Approach 1:
The capsule shell dynamics are designed to respond to environmental conditions: remaining intact during washing and storage, then rupturing or degrading under specific triggers such as mechanical abrasion during drying or chemical conditions. This dynamic behavior enables delayed release for extended active lifetime while ensuring efficient delivery when the rupture event occurs.
Solution Approach 2:
The multilayered shell structure performs preliminary protective action during storage and washing, preventing premature release. The shell is designed to maintain integrity until a predetermined release condition is met, at which point the preliminary protection ceases and rapid release occurs, optimizing both delivery efficiency and active lifetime.
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 multilayered microcapsules exhibit enhanced barrier properties against evaporation and chemical destabilization, ensuring prolonged and controlled release of fragrances, improving the longevity and stability of perfumes in consumer products.
Implementation Method 1
mixing a first and second polyelectrolytes in the aqueous vehicle under conditions sufficient to form a suspension of complex coacervate nodules; depositing the complex coacervate nodules at an interface of an aqueous vehicle adjacent the hydrophobic internal phase to form an outer shell
Implementation Method 2
introducing a water soluble reactant into the aqueous vehicle under conditions sufficient to induce interfacial polymerization of the monomer inside the outer shell to form an inner shell at the interface between the internal phase and the outer shell
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The invention relates to a method of making multilayer core/shell microcapsules for delivery of active agents such as fragrance components of perfume oils. The method includes forming an outer shell by coacervation surrounding an internal phase which contains the active agent; and forming an inner shell by interfacial polymerization at the interface between the internal phase and the outer shell. The internal phase contains the active agent. The microcapsules are typically incorporated in a consumer product wherein the multilayer shell prevents the active agent from release until desired, generally during use of the consumer product.