Electrophoretic Particle Manufacturing via Living Polymerization

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Solution Overview

Problem

Existing electrophoretic particle manufacturing methods using atom transfer radical polymerization (ATRP) result in variations in polymer density and functionality, leading to inconsistent uniformity and dispersibility of electrophoretic particles in dispersions.

Innovation Solution

A method involving the use of block copolymers, where a first monomer contributing to dispersibility, a second monomer with reactivity, and a third monomer providing charge are polymerized through living polymerization without random copolymerization, and then connected to the particle surface, ensuring uniform dispersibility and chargeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If atom transfer radical polymerization (ATRP) is used to manufacture electrophoretic particles, then the particles can be produced with coating layers, but variations in polymer density and functionality result in inconsistent uniformity and dispersibility

Engineering Contradiction:

Improveuniformity of electrophoretic particlesVSAvoiddispersibility in electrophoretic dispersion

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The coating layer is segmented into distinct functional blocks: a first block copolymer providing uniform dispersibility, a second block copolymer providing chargeability, and optionally a third block copolymer providing additional functionality. This segmentation ensures that each function is performed by a dedicated polymer block with controlled properties, eliminating the variability inherent in conventional ATRP methods.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electrophoretic particle uses a composite coating structure consisting of multiple block copolymers with different functions. The first block copolymer (e.g., polyethylene glycol-based) provides dispersibility, the second block copolymer (e.g., polyacrylic acid-based) provides chargeability, and they are combined in a controlled manner to achieve both uniformity and reliability simultaneously.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If silane coupling agents with polymerization initiation groups are bonded to the base particle surface and monomers are polymerized, then chargeability and dispersibility are imparted, but variations in silane coupling agent density and monomer type cause variations in polymerization degree

Engineering Contradiction:

Improveability to impart chargeability and dispersibilityVSAvoidpolymerization degree uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The base particle surface is preliminarily treated with silane coupling agents at controlled densities before polymerization. This preliminary action ensures uniform distribution of polymerization initiation sites, which subsequently leads to uniform polymerization degree across all particles. The silane coupling agents are bonded under controlled conditions to achieve consistent surface coverage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The polymerization process parameters are precisely controlled, including monomer concentration, polymerization temperature, and reaction time. By optimizing these parameters, the polymerization degree is maintained within a narrow range (e.g., 10-100 kDa), ensuring uniformity across all electrophoretic particles while still achieving the desired chargeability and dispersibility.

Inventive Principle:

Principle #35Parameter changes

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 enables the production of electrophoretic particles with consistent uniform dispersibility and chargeability, enhancing the reliability of electrophoretic dispersions, sheets, and devices.

Implementation Method 1

polymerizing a first monomer having a site contributing to dispersibility into a dispersion medium, a second monomer including a second functional group having reactivity with the first functional group, a positively or negatively-charged third monomer by living polymerization without random copolymerizing the first monomer and the second monomer

Methodology Applied

Scientific EffectLiving polymerization: Photopolymerisation

Implementation Method 2

when an electric field is applied to a dispersion system in which particles are dispersed in a liquid, particles are moved (migrated) in a liquid by the Coulomb force. This phenomenon is referred to as electrophoresis.

Methodology Applied

Scientific EffectElectrophoresis: Electrophoresis

Data Source

PatentUS9798215B2Method of manufacturing electrophoretic particle, electrophoretic particle, electrophoretic dispersion, electrophoretic sheet, electrophoretic device, and electronic apparatus

Publication Date: 2017.10.24 E INK CORP

AI summary

There is provided a method of manufacturing an electrophoretic particle, in which the electrophoretic particle includes a mother particle and a block copolymer, including: a step of polymerizing a monomer M having a site contributing to dispersibility into a dispersion medium, a monomer M including a second functional group having reactivity with the first functional group, a charged monomer M by living polymerization without random copolymerizing the monomer M1 and the monomer M2 so as to obtain the block copolymer; and a step of reacting the first functional group and the second functional group to a bonding section to a mother particle so as to connect the block copolymer to the mother particle.