Colored Polymer Particles for Electrophoretic Displays
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Solution Overview
Problem
Current electrophoretic displays (EPDs) face challenges in producing colored particles that are easily dispersible in non-polar media, maintain electrophoretic mobility, and prevent color leaching, while also requiring complex and costly processes for preparation and dye incorporation.
Innovation Solution
Development of colored polymer particles with monomer units including polymerizable dyes, charged co-monomers, and crosslinking agents, which are synthesized in a one-step process to ensure dye irreversibility and optimal dispersibility, allowing for precise control over particle size, charge, and color, and are designed to prevent dye leaching into non-polar solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dye incorporation methods are used, then color can be added to particles, but the dye leaches into non-polar media and requires complex multi-step processes
Solution Approach 1:
The patent combines the dye molecule and polymer monomer into a single integrated structure where the dye contains polymerizable groups that become covalently bonded to the polymer chain during polymerization. This merging eliminates the need for separate dye incorporation steps and prevents leaching while maintaining color stability.
Solution Approach 2:
The dye is pre-modified with polymerizable groups before polymerization, allowing it to be incorporated into the polymer structure during the polymerization process itself. This preliminary preparation enables single-step synthesis of colored particles without subsequent dyeing or coating steps.
2Ease of operation
If charged particles are used for electrophoretic mobility, then electrophoretic function is achieved, but dispersibility in non-polar media becomes difficult
Solution Approach 1:
The patent creates composite particles combining hydrophobic polymer segments (for non-polar media compatibility) with charged functional groups (for electrophoretic mobility). The polymer structure integrates both non-polar hydrocarbon chains and ionic groups, allowing simultaneous achievement of dispersibility and electrophoretic function.
Solution Approach 2:
Different regions of the polymer particle exhibit different properties: the bulk polymer provides non-polar character for dispersibility, while surface-localized charged groups provide electrophoretic mobility. This spatial differentiation of properties resolves the contradiction between dispersibility and electrophoretic function.
3Reliability
If multiple processing steps are used for particle preparation, then dye incorporation and charge addition can be achieved, but production cost and time increase
Solution Approach 1:
The polymerization process serves multiple functions simultaneously: it forms the particle structure, incorporates the color through polymerizable dye groups, and adds charge through charged monomers or co-monomers. This multi-functionality eliminates sequential processing steps and accelerates production.
Solution Approach 2:
The patent merges particle formation, coloring, and charging into a single polymerization reaction step. All three functions are achieved concurrently through careful selection of monomers and dyes with appropriate functional groups, dramatically improving production efficiency.
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 enables the production of high-quality, monodisperse colored particles with enhanced electrophoretic mobility and optical clarity, reducing production costs and complexity, while ensuring stable color retention and improved image quality in EPDs.
Implementation Method 1
coloured polymer particles...comprising monomer units of a) at least one polymerisable dye comprising a chromophore, at least two polymerisable groups
Implementation Method 2
If a voltage is applied between the electrodes, charged particles move to the electrode of opposite polarity
Data Source
AI summary
This invention relates to coloured polymer particles preferably with surface functionality for charge retention, a process for their preparation, the use of these particles for the preparation of an electrophoretic device, colour electrophoretic displays comprising such particle, and new polymerisable dyes.