SEBS Ion-Exchange Membrane for Bistable Electro-Optic States
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Solution Overview
Problem
Conventional electro-optic devices require constant electrical potential to maintain an activated, colored or darkened state, leading to high power consumption and impracticality in certain applications due to self-erasing when the potential is removed.
Innovation Solution
An electro-optic device with a bi-stable ion exchange membrane made of styrene-ethylene-butylene-styrene (SEBS) block polymers, functionalized with quaternized amine or ammonium cations, inhibits diffusion of cations between compartments, allowing anodic and cathodic species to remain in activated states without continuous power, using an anionic exchange membrane to prevent cation passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant electrical potential is applied to maintain activated state, then device remains in darkened state, but power consumption increases
Solution Approach 1:
The ion exchange membrane is pre-functionalized with quaternized amine or ammonium cations that are primarily attached to the polystyrene block. This preliminary chemical modification creates fixed positive charges that permanently repel cations, establishing the barrier function before the device is activated. As a result, when electrical potential is applied to darken the device, the cation diffusion barrier is already in place to prevent self-erasing, eliminating the need for continuous power application.
Solution Approach 2:
The invention uses a composite structure combining SEBS block polymers (polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene) with quaternized amine or ammonium cations. The polystyrene blocks provide the structural framework while the functionalized cations provide the electrostatic barrier. This composite material approach creates a membrane that simultaneously provides mechanical integrity and cation diffusion inhibition, resolving the contradiction between maintaining device state and reducing power consumption.
2Reliability
If ion exchange membrane is functionalized with quaternized amine or ammonium cations, then cation diffusion is inhibited, but manufacturing complexity increases
Solution Approach 1:
The functionalization is localized specifically to the polystyrene blocks of the SEBS copolymer, rather than requiring modification of the entire polymer structure. The quaternized amine or ammonium cations are primarily attached to the polystyrene blocks, creating localized positive charge regions at the membrane interfaces where cation diffusion occurs. This localized functionalization approach simplifies manufacturing compared to uniform functionalization of the entire polymer matrix.
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 device maintains an activated, colored state for a predetermined period without continuous power, reducing power consumption and enabling applications with memory and less self-erasing.
Implementation Method 1
anionic exchange membrane to prevent cation passage
Implementation Method 2
functionalized with quaternized amine or ammonium cations, inhibits diffusion of cations between compartments
Implementation Method 3
At least one of the cathodic species and the anodic species may be operable between an activated and an un-activated state based, at least in part, on an applied electrical potential
Data Source
AI summary
An electro-optic device may comprise a first substrate having a first surface and a second surface; a second substrate having a third surface and a fourth surface, the second substrate disposed in a spaced-apart relationship relative to the first substrate such that the second and third surfaces are generally parallel to and face one another; a first electrode associated with the second surface; a second electrode associated with the third surface; a styrene-ethylene-butylene-styrene (SEBS) anionic exchange membrane disposed between the first and second electrodes; a first compartment defined by the SEBS anionic exchange membrane and the first substrate; a second compartment defined by the SEBS anionic exchange membrane and the second substrate; a cathodic species disposed in the first compartment; and an anodic species disposed in the second compartment.