Modified Chitosan Polyurea Capsules for Low-Leakage Deposition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing microencapsulation processes face challenges with chitosan due to its insolubility in water above pH 7, leading to handling difficulties and incompatibility with certain matrices, resulting in poor deposition efficiency and high leakage.
Innovation Solution
A process that modifies chitosan to be soluble at higher pH levels by hydrolyzing it with acid and reacting it with modifying compounds like epoxides or α,β-unsaturated compounds, forming a cross-linked polyurea shell with tailored surface charge, enabling higher concentration use and improved compatibility with matrices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chitosan is used as a cross-linker in microencapsulation, then the capsule shell can be formed, but chitosan is insoluble in water above pH 7, causing handling difficulties and poor deposition efficiency
Solution Approach 1:
The patent modifies chitosan by introducing hydrophilic groups (carboxyl, hydroxyl, or amine groups) through chemical modification. This changes the solubility parameter of chitosan, enabling it to dissolve in water at neutral to alkaline pH levels (pH 7-11), thereby eliminating handling difficulties while maintaining its cross-linking capability for capsule shell formation
Solution Approach 2:
The patent creates a composite material by chemically modifying chitosan to incorporate hydrophilic functional groups. This composite modified chitosan maintains the biocompatibility and cross-linking properties of natural chitosan while adding water solubility at neutral to alkaline pH, resolving the contradiction between shell formation capability and ease of handling
2Reliability
If chitosan is used at high concentration to improve shell formation, then capsule shell can be formed, but chitosan is insoluble in water above pH 7, resulting in poor deposition efficiency
Solution Approach 1:
The patent chemically modifies chitosan by introducing hydrophilic groups (carboxyl, hydroxyl, or amine groups) that change its solubility parameters. This enables chitosan to dissolve at high concentrations in water at neutral to alkaline pH levels, thereby improving deposition efficiency while maintaining reliable capsule shell formation
Solution Approach 2:
The patent creates a functional copy of chitosan with improved properties by chemically modifying it to introduce hydrophilic groups. This modified version retains the essential cross-linking functionality needed for shell formation while gaining water solubility at higher pH levels, enabling better deposition efficiency
3Reliability
If chitosan is used in microencapsulation, then capsule shell can be formed, but chitosan is incompatible with certain matrices, resulting in high leakage
Solution Approach 1:
The patent modifies chitosan by introducing hydrophilic functional groups (carboxyl, hydroxyl, or amine groups) that change its interaction parameters with different matrices. This modification improves compatibility with various matrices including consumer products, thereby reducing leakage while maintaining reliable capsule shell formation
Solution Approach 2:
The patent creates a composite modified chitosan material that combines the biocompatibility and cross-linking properties of natural chitosan with improved matrix compatibility through introduced hydrophilic groups. This composite material reduces harmful interactions with matrices, thereby minimizing leakage while maintaining shell formation reliability
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 modified chitosan polyurea capsules exhibit reduced leakage, enhanced deposition efficiency, and improved compatibility with consumer product matrices, with tailored surface charge and degradability, addressing the limitations of traditional chitosan use in microencapsulation.
Implementation Method 1
The chitosan is hydrolyzed by treating with acid to enable the chitosan to be soluble even at pH above 5
Implementation Method 2
A water soluble or dispersible modifying compound is added to the emulsion or the water phase... The modifying compound contains cationic, anionic, or nonionic groups... formed by reaction with a multifunctional electrophile
Implementation Method 3
the shell comprises a reaction product of at least one modified chitosan and at least one polyisocyanate... Jabs et al., U.S. Pat. No. 4,847,152 teaches microcapsules with polyurea walls. The wall is the reaction product of an aromatic isocyanate with an isocyanate reactive group
Implementation Method 4
The emulsion is heated to at least 40° C., for a time sufficient to form a shell at an interface of the droplets with the water phase
Data Source
AI summary
An improved polyurea and chitosan core-shell delivery particles encapsulating a benefit agent is described. Chitosan is pre-modified with a modifying compound which is cationic, anionic, or nonionic. Alternatively the modification is accomplished in situ. The modifying compound is selected from the group consisting of an epoxide, aldehyde, or an α,β-unsaturated compound, and is reactive with free amine moieties of chitosan, covalently bonding through CN bonds with the amine moieties of the chitosan. The modifying compound can contain acidic, hydroxyl, and quaternary ammonium groups. The reaction product of the chitosan, the modifying compound along with an electrophile, preferably a polyisocyanate yields a microcapsule with charge, improved release characteristics, improved compatibility or enhanced degradation characteristics, such as in OECD test method 301B.