Biodegradable Microcapsule Shell via Interfacial Polyurea
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Solution Overview
Problem
Conventional controlled release microcapsules face issues such as premature release of active agents in surfactant-containing solutions, poor environmental biodegradability, limited encapsulation breadth, mechanical instability, inadequate adhesion to substrates, and inefficient release profiles, particularly in rinse-off applications like cleaning products.
Innovation Solution
The development of microcapsules with a modified shell composition incorporating biodegradable resins, which are made reactive through pre-treatment, and a method involving an oil phase with isocyanates, epoxies, organofunctional silanes, and amine moieties, combined with natural materials, to form a membrane that enhances barrier properties and environmental biodegradability while allowing controlled release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If highly crosslinked membranes are used to reduce swelling and solubility, then barrier properties are improved, but environmental biodegradability deteriorates
Solution Approach 1:
The patent uses composite materials by combining biodegradable polymers (starch, cellulose, chitosan, gelatin, albumin) with controlled crosslinking density. The membrane comprises a biodegradable polymer matrix with crosslinks formed by natural crosslinking mechanisms (enzyme-mediated, chemical crosslinkers like glutaraldehyde or genipin) that provide sufficient structural integrity while maintaining biodegradability. This composite approach allows the membrane to resist premature dissolution in aqueous formulations while remaining accessible to environmental microbes for degradation.
2Reliability
If microcapsules are made stable to prevent premature release, then reliability is improved, but mechanical stability during processing deteriorates
Solution Approach 1:
The patent optimizes membrane parameters including crosslinking density, polymer molecular weight, and membrane thickness to achieve the desired balance. By controlling the degree of crosslinking (not too high to maintain biodegradability, not too low to ensure stability) and selecting appropriate polymer characteristics, the membrane achieves sufficient mechanical strength to withstand processing (extrusion, granulation, coating) while maintaining stability to prevent premature active ingredient release during storage and application.
3Reliability
If conventional membrane materials are used to provide controlled release, then release control is improved, but adhesion to substrates deteriorates
Solution Approach 1:
The patent applies local quality by incorporating adhesion-promoting functional groups (carboxyl, hydroxyl, amine groups) at specific locations on the membrane surface or within the polymer structure. The biodegradable polymers used (starch, cellulose, chitosan, gelatin, albumin) naturally contain these functional groups that can form hydrogen bonds, electrostatic interactions, or covalent bonds with substrate surfaces. This localized adhesion enhancement allows the microcapsules to effectively deposit and adhere to substrates (fabrics, skin, hair) while maintaining their controlled release functionality through the membrane's diffusion barrier properties.
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 solution achieves improved barrier properties, increased environmental biodegradability, and enhanced adhesion to substrates, enabling sustained release of active agents in challenging conditions, including surfactant-containing solutions and rinse-off applications, while maintaining a favorable environmental profile.
Implementation Method 1
a shell material is manufactured within the dispersed phase, and migration of the shell material is induced via an interfacial reaction
Implementation Method 2
A high degree of crosslinking within the membrane can reduce swelling and solubility
Implementation Method 3
environmentally biodegradable polymers generally swell in water, or are soluble in water
Implementation Method 4
An emulsion comprising the active material (dispersed phase) is stabilized in a continuous phase
Data Source
AI summary
A method is disclosed for preparing a composition including controlled release particles includes: (a) preparing an oil phase including at least one hydrophobic active ingredient, at least one isocyanate, at least one epoxy, at least one organofunctional silane, optionally at least one pre-reacted natural material resin, and optionally a plasticizer; (b) preparing an aqueous phase comprising an emulsifier; (c) combining the oil phase and the aqueous phase to provide an aqueous suspension; (d) adding at least one amine moiety containing material to provide a barrier; (e) heating; (f) adding a natural material to provide a microcapsule having hydroxyl moieties or amine moieties on a surface thereof; (g) adding an aldehyde to react with the surface moieties; and (h) adding structuring agents to provide the controlled release particles homogeneously suspended in an aqueous dispersion. The composition is also disclosed.