Biodegradable Microcapsules via Photopolymerized Crosslinked Shell
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Solution Overview
Problem
Current microcapsules with crosslinked shells are not biodegradable, leading to environmental concerns due to non-degradable materials and issues with active ingredient retention and protection.
Innovation Solution
A method involving the preparation of solid microcapsules with a crosslinked shell using a polymeric composition containing monomers, crosslinking agents, and photoinitiators, forming a double emulsion that is then polymerized to create biodegradable capsules without the need for surfactants, ensuring controlled size and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crosslinked shell is formed using conventional materials (e.g., urea and formaldehyde), then diffusion is slowed and retention is improved, but biodegradability is lost
Solution Approach 1:
The patent uses a composite shell structure combining biodegradable polymer matrix (polyester, polysaccharide, or their copolymers) with crosslinked network formed by multifunctional crosslinking agents. This composite approach maintains the protective barrier function while ensuring biodegradability through enzymatic or hydrolytic degradation of the polymer chains.
Solution Approach 2:
The patent modifies the chemical parameters of biodegradable polymers by introducing reactive functional groups (carboxyl, hydroxyl, amino, epoxy, isocyanate) that can form crosslinked structures. This parameter change enables the formation of a crosslinked protective shell while maintaining the underlying biodegradable nature of the polymer backbone.
2Object-generated harmful factors
If non-crosslinked biodegradable materials (e.g., hydrogel or thermoplastic polymer) are used for the shell, then biodegradability is achieved, but diffusion is rapid and retention is limited
Solution Approach 1:
The patent performs preliminary chemical modification of biodegradable polymer chains by introducing crosslinking functional groups before encapsulation. This preliminary crosslinking action creates a pre-formed protective network that will maintain its integrity during encapsulation and provide controlled diffusion, while remaining biodegradable.
Solution Approach 2:
The patent creates local crosslinked regions within the polymer matrix that provide enhanced protective properties where needed, while maintaining the overall biodegradable character of the material. The crosslinking density can be controlled to provide optimal balance between retention and biodegradability in different regions of the shell.
3Reliability
If conventional encapsulation methods are used, then active ingredients are isolated, but harmful reactions with other components occur and stability is reduced
Solution Approach 1:
The patent uses the crosslinked biodegradable polymer shell as an intermediary barrier between the active ingredient and the external environment. This intermediary layer provides selective permeability, allowing controlled release of the active ingredient while preventing harmful interactions with other formulated product components.
4Reliability
If crosslinking agents and photoinitiators are added to form a crosslinked shell, then diffusion is reduced and retention is improved, but the process complexity increases
Solution Approach 1:
The patent replaces conventional thermal or chemical crosslinking processes with photopolymerization using UV or visible light initiation. This substitution allows for spatial and temporal control of the crosslinking process, enabling shell formation during or after encapsulation without requiring complex temperature control or prolonged chemical reaction times.
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 method produces biodegradable microcapsules with improved retention and protection of active ingredients, meeting OECD biodegradability standards and avoiding uncontrolled release, while eliminating the use of surfactants that could react with other components.
Implementation Method 1
composition C2 comprising: at least one monomer or polymer selected from the group formed by aliphatic or aromatic esters or polyesters, anhydrides or polyanhydrides, saccharides or polysaccharides, ethers or polyethers, amides or polyamides and carbonates or polycarbonates, additionally carrying at least one function selected from the group formed by acrylate, methacrylate, vinyl ether, N-vinyl ether, epoxy, siloxane, amine, lactone, phosphate, carboxylate functions, and mixtures thereof, at least one crosslinking agent, and optionally at least one photoinitiator or crosslinking catalyst
Implementation Method 2
at least one crosslinking agent
Implementation Method 3
after which an emulsion (E1) is obtained comprising droplets of composition C1 dispersed in composition C2
Data Source
AI summary
The present invention relates to a method for preparing solid microcapsules, comprising the following steps a) adding, with stirring, a composition C1 to a polymeric composition C2 comprising at least one aliphatic or aromatic ester or polyester, additionally bearing at least one function selected from the group consisting of acrylate, methacrylate, vinyl ether, N-vinyl ether, epoxy, siloxane, amine, lactone, phosphate and carboxylate functions and mixtures thereof, whereby an emulsion (E1) is obtained comprising droplets of composition C1 dispersed in a composition C2; b) adding, with stirring, the emulsion (E1) to a composition C3 whereby a double emulsion (E2) is obtained comprising droplets dispersed in the composition C3; c) applying shear to the emulsion (E2) whereby a double emulsion (E3) is obtained comprising droplets of controlled size dispersed in the composition C3; and d) polymerizing the composition C2, whereby solid microcapsules dispersed in the composition C3 are obtained.