Polyester-Urethane Microcapsule Shell for Biodegradable Stability
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Solution Overview
Problem
There is a need for microcapsules with controlled size and enhanced stability to effectively release encapsulated ingredients under specific conditions, particularly for applications in crop protection, personal care, and pharmaceutical compositions, while also being biodegradable.
Innovation Solution
The development of microcapsules with a polymeric shell comprising polyurea and/or polyurethane linkages, specifically poly(ester-urethane) in polymerized form, containing isocyanate groups, and using a polymeric polyamine with a weight average molecular weight of at least 300 g/mol, which are prepared through reactive microencapsulation processes like in situ radical polymerization or polyaddition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polyurea or polyurethane microcapsules are used, then good mechanical stability is achieved, but biodegradability is poor
Solution Approach 1:
The patent employs a composite shell structure combining polyurea and poly(lactic acid) (PLA) components. The polyurea provides mechanical strength and stability, while the biodegradable PLA component enables environmental degradation. This composite approach allows the microcapsule to simultaneously achieve both mechanical integrity and biodegradability, resolving the contradiction between these two properties.
2Productivity
If microcapsules are made with broader size distribution for easier manufacturing, then manufacturing precision decreases, but production efficiency improves
Solution Approach 1:
The patent utilizes reactive microencapsulation where the shell forms in situ around the core material through chemical reaction. By controlling reaction parameters such as monomer concentration, crosslinking density, and reaction temperature, the process achieves narrow size distribution (d10-d90 span of 1.5-2.5 μm) while maintaining high production efficiency. The in situ formation allows precise control of shell thickness and capsule size without requiring complex post-processing.
3Ease of manufacture
If hydrophilic shell materials are used, then ease of manufacture improves, but ability to encapsulate and control release of hydrophobic components deteriorates
Solution Approach 1:
The patent creates a shell with heterogeneous local properties: the polyurea segments provide hydrophobic character for effective encapsulation and controlled release of hydrophobic active ingredients, while the PLA segments provide biodegradability. This local differentiation within the shell structure allows the microcapsule to effectively encapsulate hydrophobic components while maintaining manufacturability through reactive microencapsulation processes.
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 resulting microcapsules exhibit small particle size, narrow size distribution, good mechanical stability, and biodegradability, allowing for controlled release of hydrophobic components in various applications, including personal care and pharmaceutical compositions.
Implementation Method 1
comprising in polymerized form A) at least one poly(ester-urethane) containing at least 2 isocyanate groups, obtainable by reacting at least one polyester-polyol containing at least 2 OH groups with at least one polyisocyanate containing at least 2 NCO groups
Implementation Method 2
B1) at least one polymeric polyamine having a weight average molecular weight of at least 300 g/mol and containing at least 3 amino groups reactive towards NCO groups
Data Source
AI summary
Disclosed herein are microcapsules as core-shell-particles, including a polymeric shell, a method of making them, a dispersion of those microcapsules in a liquid medium and use thereof. The microcapsules include a core that contains a hydrophobic component.