Water-in-Oil Microcapsule Wall Formation via Controlled Polymerization
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Solution Overview
Problem
Existing microencapsulation processes fail to produce capsules with low permeability and durability, particularly for heat-sensitive applications, and lack control over permeability characteristics, which is crucial for various industrial uses.
Innovation Solution
A novel method for forming water in oil (W/O) and oil in water (O/W) microcapsules involves dispersing oil-soluble amine modified polyvinyl monomers with free radical initiators and organic acids, followed by controlled heating and emulsification steps to form microcapsule walls at the interface of the two phases, allowing for controlled permeability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microencapsulation processes are used, then capsule formation is achieved, but the capsules exhibit high permeability and poor durability
Solution Approach 1:
The patent applies parameter changes by systematically varying polymerization conditions including temperature (50-90°C), time (2-24 hours), and monomer ratios to optimize capsule wall properties. This resolves the contradiction by finding specific parameter combinations that simultaneously reduce permeability and enhance durability through controlled polymerization reactions.
Solution Approach 2:
The patent uses composite materials by combining different monomers (amine-modified polyvinyl monomers with polyfunctional vinyl monomers) to create capsule walls with tailored properties. This composite approach enables simultaneous achievement of low permeability and high durability that cannot be obtained with single materials.
2Manufacturing precision
If capsule wall materials are selected for low permeability, then permeability control is improved, but the process complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-mixing monomers, initiators, and emulsifiers before polymerization, and by conducting a preliminary emulsification step to create stable droplet distributions. This preliminary preparation simplifies the overall process while enabling precise permeability control during the actual polymerization phase.
Solution Approach 2:
The patent uses an intermediary approach by employing emulsifiers as mediators between the hydrophobic monomers and hydrophilic aqueous phase. This intermediary substance enables controlled polymerization at the interface while simplifying the process through standardized emulsification procedures that can be applied across different formulations.
3Strength
If heat treatment is applied to polymerize wall material, then capsule strength is improved, but heat-sensitive core materials may be damaged
Solution Approach 1:
The patent applies dynamics by using a staged polymerization approach where temperature and time are dynamically adjusted in multiple phases. The process begins at lower temperatures to protect heat-sensitive materials, then progressively increases temperature to build wall strength, resolving the contradiction through dynamic process control.
Solution Approach 2:
The patent uses parameter changes by systematically varying polymerization temperature and time parameters to achieve the desired balance between wall strength and core material protection. Specific parameter ranges (50-90°C, 2-24 hours) are optimized to simultaneously achieve adequate capsule strength while minimizing thermal exposure to the core.
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
This method enables the production of microcapsules with controlled permeability, suitable for diverse applications, including heat-sensitive materials, by selecting wall materials and adjusting cross-linking conditions, resulting in capsules with low leakage and tailored release profiles.
Implementation Method 1
heating for a time and temperature sufficient to decompose the free radical initiators thereby oligomerizing the amine modified polyfunctional polyvinyl monomer and polyfunctional vinyl monomer or oligomer
Implementation Method 2
The free radical polymerization is believed to be driven by a reaction between the amine modified polyfunctional polyvinyl monomer and the organic acid to form an ionic structure which drives the wall material to the oil water interface
Implementation Method 3
decompose the free radical initiators thereby oligomerizing the amine modified polyfunctional polyvinyl monomer and polyfunctional vinyl monomer or oligomer forming a pre-polymer
Implementation Method 4
adding to the internal phase oil a water phase comprising a dispersion in water of an anionic emulsifier
Data Source
AI summary
A novel method of forming water in oil microcapsules is disclosed. According to the invention microcapsules are obtained by steps comprising dispersing an oil soluble amine modified polyfunctional polyvinyl monomer and an oil soluble bi- or polyfunctional vinyl monomer along with a thermal or UV free radical initiator (optionally included in one or both of the oil or water phases) and an organic acid into an internal phase oil; heating or UV exposing for a time (and temperature) sufficient to oligomerize the amine modified polyfunctional polyvinyl monomer and oil soluble bi- or polyfunctional vinyl monomer forming a pre-polymer. Thereafter the process involves adding to the oil phase oil a water phase comprising a dispersion in water of an anionic emulsifier (and optionally initiator), and adding an emulsifying agent. Emulsifying the water phase into the oil phase (W/O) is controlled through the quantity of water employed. The emulsion is then UV exposed or heated for a time (and temperature) sufficient to decompose the free radical initiators in the oil and/or water phases; thereby forming microcapsule wall material at the interface of the water and oil phases.