Block Copolymer Grafted Pigments for Clear State Electrophoretic Inks
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Solution Overview
Problem
Current electrophoretic display technologies are limited to color and white states or black and white states, unable to provide a clear or transparent state, which restricts the use of stacked architecture designs for print-like color transitions.
Innovation Solution
The development of novel electronic inks using tri-block or di-block copolymers grafted onto pigment surfaces via azide chemistry, providing stable and charged particle dispersions that enable both clear and colored states through covalent bonding, minimizing the need for additional surfactants and charge directors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional electrophoretic display technology is used, then color and white states or black and white states can be provided, but clear or transparent states cannot be achieved
Solution Approach 1:
The patent changes the chemical parameters of the pigment surface by introducing azide groups and grafting block copolymers. This chemical modification enables the pigment particles to achieve both colored and clear states through controlled aggregation and dispersion, resolving the contradiction between providing clear states and maintaining stacked architecture capability
Solution Approach 2:
The patent creates composite structures by grafting block copolymers onto pigment surfaces. The composite material combines the optical properties of pigments with the stabilizing and charging properties of copolymers, enabling clear state transitions while maintaining compatibility with stacked architecture designs
2Reliability
If additional surfactants and charge directors are used to stabilize pigment dispersions, then particle stability improves, but device complexity increases
Solution Approach 1:
The grafted block copolymers perform multiple functions simultaneously: they stabilize pigment dispersions through steric hindrance, provide charge for electrophoretic actuation, and prevent aggregation. This multi-functionality eliminates the need for separate surfactants and charge directors, reducing device complexity while maintaining particle dispersion stability
Solution Approach 2:
The patent merges the functions of surfactants and charge directors into a single grafted block copolymer structure. The copolymer chains attached to pigment surfaces simultaneously provide steric stabilization and electrical charge, consolidating multiple additives into one integrated component
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 solution allows for the creation of robust electronic inks with improved switching behavior and longer lifetimes, enabling the achievement of bright, neutral white states and precise color control in stacked full-color electro-optical displays.
Implementation Method 1
The azide group reacts with the pigment surface to covalently bond the block copolymer to the pigment, stabilizing the pigment in non-polar solvents
Implementation Method 2
Electrophoretic actuation relies on particles moving under the influence of an electric field
Data Source
AI summary
Pigment based inks are provided. The inks include a non-polar carrier fluid; and a surface-functionalized pigment particle including a nitrogen-inked moiety to the surface of the pigment particle through a nitrogen link at one end of the nitrogen-linked moiety and a block copolymer having at least two blocks attached at another end, the pigment particle suspended in the non-polar carrier fluid. A combination of an electronic display and an electronic ink employing the pigment and a process for making the pigment-based inks are also provided.