Core-Shell Fine Particle Production via Soap-Free Emulsion Polymerization
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Solution Overview
Problem
Conventional methods for producing core-shell fine particles fail to achieve submicron sizes with high crosslink density, leading to functional insufficiency due to core swelling and aggregation issues, which affects the primary functions of both the core and shell layers.
Innovation Solution
A method involving the absorption of a monomer mixture containing 15 to 99% crosslinkable monomers and 1 to 85% ATRP initiating group monomers in organic seed particles, followed by polymerization and graft polymerization to form a core-shell structure with a high crosslink density, maintaining the submicron size and preventing core swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If precipitation polymerization is used to produce fine particles containing ATRP initiating group, then high crosslink density is achieved, but particle size becomes too large (2 to 5 μm) and submicron size cannot be obtained
Solution Approach 1:
The invention changes the polymerization parameters by using soap-free emulsion polymerization instead of precipitation polymerization, controlling the particle size to submicron range (0.1-1 μm) while maintaining high crosslink density through optimized monomer composition (10-50 mass% crosslinkable monomer) and polymerization conditions
Solution Approach 2:
The invention creates local high crosslink density within the particle structure by controlling the distribution and concentration of crosslinkable monomers during polymerization, ensuring sufficient crosslinking throughout the particle volume while maintaining small particle size
2Manufacturing precision
If soap-free emulsion polymerization is used to obtain submicron-size fine particles, then monodispersity is achieved, but crosslink density becomes low and aggregation occurs
Solution Approach 1:
The invention optimizes the parameter of crosslinkable monomer content to 10-50 mass% of total monomers, which is sufficient to achieve high crosslink density while maintaining particle stability and preventing aggregation during soap-free emulsion polymerization
Solution Approach 2:
The invention creates a composite particle structure combining crosslinked polymer networks with emulsion polymerization morphology, achieving both monodispersity from emulsion process and high crosslink density from crosslinkable monomer incorporation
3Reliability
If crosslinkable monomer content is increased to not less than 10% by mass for high crosslink density, then aggregation increases and productivity decreases
Solution Approach 1:
The invention identifies the critical parameter range of 10-50 mass% crosslinkable monomer content, where sufficient crosslinking occurs without excessive aggregation, optimizing the balance between particle stability and productivity
Solution Approach 2:
The invention uses a moderate amount of crosslinkable monomer (10-50 mass%) rather than high amounts, providing just sufficient crosslinking to prevent aggregation and maintain particle integrity without causing excessive crosslinking that would lead to aggregation and reduced productivity
4Ease of manufacture
If low crosslink density core fine particle is used, then core swelling occurs during shell layer formation, but this prevents core and shell from fulfilling their primary functions
Solution Approach 1:
The invention performs preliminary crosslinking of the core particle before shell layer formation, creating a pre-crosslinked core structure that resists swelling during subsequent shell polymerization, ensuring both layers can fulfill their functions
Solution Approach 2:
The invention applies preliminary crosslinking to the core particle to prevent the harmful effect of core swelling during shell layer formation, counteracting the tendency toward swelling before it occurs and maintaining functional integrity
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 approach allows for the production of monodispersed crosslinked core-shell fine particles with a submicron size and high crosslink density, enabling both the core and shell layers to fulfill their primary functions effectively, enhancing the functional properties of the particles.
Implementation Method 1
allowing a monomer mixture to be absorbed in organic monodispersed seed particles
Implementation Method 2
polymerizing the monomer mixture using a polymerization initiator, thereby producing a core layer
Implementation Method 3
atom transfer radical polymerization (ATRP), has recently attracted attention since a graft chain can be formed densely on the surface of a polymer fine particle
Implementation Method 4
containing 15 to 99% by mass of a crosslinkable monomer having a plurality of vinyl groups
Data Source
AI summary
A core-shell fine particle (10) is produced as follows. First of all, a monomer mixture containing 15-99% by mass of a crosslinkable monomer and 1-85% by mass of a monomer having an ATRP initiating group is adsorbed into an organic monodispersed seed particle. Next, the monomer mixture is polymerized by a polymerization initiator, thereby forming a core layer composed of a monodispersed crosslinked fine particle (11) containing an ATRP initiating group (12). A shell layer (13) is then formed by graft polymerizing a monomer onto the thus-obtained core layer.