Functional Polymer Membrane pH Resistance and Electric Resistance

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Solution Overview

Problem

Existing ion-exchange membranes lack excellent pH resistance and dimensional stability, particularly when exposed to long-term electrodialysis processes, leading to issues like calcium and magnesium ion precipitates and increased electric resistance.

Innovation Solution

A functional polymer membrane is developed with specific constitutional units, including a polyfunctional monomer with a ClogP value between -0.3 and 3.0, which improves pH resistance, reduces electric resistance, and enhances selective permeability and dimensional stability by hydrophobizing the membrane.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ion-exchange membranes are used in electrodialysis processes, then ion removal function is achieved, but pH resistance deteriorates and dimensional stability decreases over time

Engineering Contradiction:

ImprovepH resistanceVSAvoidservice life in electrodialysis

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical composition parameters of the membrane by incorporating specific constitutional units (Formula I with sulfonate groups, Formula II with carboxylate groups, and Formula III hydrophobic units) in controlled ratios. This compositional parameter change enables the membrane to maintain both ion-exchange functionality and enhanced pH resistance, resolving the contradiction between reliability and service life

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite membrane structure combining hydrophilic ion-exchange units (Formula I and II) with hydrophobic stabilizing units (Formula III). This composite approach allows the membrane to simultaneously achieve good pH resistance from the hydrophobic regions and maintained dimensional stability, while preserving ion removal function through the hydrophilic regions

Inventive Principle:

Principle #40Composite materials

2Reliability

If conventional ion-exchange membranes are used, then ion removal is achieved, but electric resistance increases due to calcium and magnesium ion precipitates

Engineering Contradiction:

Improveelectric resistance stabilityVSAvoidcalcium and magnesium ion precipitates

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful effect of calcium and magnesium ions by incorporating specific functional groups (sulfonate and carboxylate units in Formula I and II) that have high affinity for these divalent cations. These units selectively bind calcium and magnesium ions, preventing them from forming precipitates that would increase electric resistance, thus transforming the harmful precipitation effect into a beneficial ion-selective binding function

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If membrane hydrophobicity is increased to improve pH resistance, then pH resistance improves, but ion exchange capacity may decrease

Engineering Contradiction:

ImprovepH resistanceVSAvoidion exchange capacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies local quality by creating distinct functional regions within the membrane structure. Formula III units provide localized hydrophobic domains that enhance pH resistance in specific areas, while Formula I and II units provide localized hydrophilic ion-exchange domains that maintain ion exchange capacity. This spatial differentiation of properties allows both requirements to be satisfied simultaneously in different parts of the membrane

Inventive Principle:

Principle #3Local quality

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 membrane exhibits excellent pH resistance, low electric resistance, and dimensional stability, making it suitable for long-term ion-exchange applications without the need for acid washing and maintaining performance in varying pH conditions.

Implementation Method 1

a polyfunctional monomer having a ClogP value of equal to or greater than -0.3 to less than 3.0 as a constitutional unit B

Methodology Applied

Scientific EffectHydrophobizing: Hydrophobe

Implementation Method 2

A functional polymer membrane is used as an ion-exchange membrane for electrodeionization (EDI), continuous electrodeionization (CEDI), electrodialysis (ED), electrodialysis reversal (EDR), and the like

Methodology Applied

Scientific EffectIon exchange: Ion Exchange

Data Source

PatentEP3290103B1Functional polymer membrane , separation membrane module and ion exchange device

Publication Date: 2021.07.14 FUJIFILM CORP

Figure 1

AI summary

Provided are a functional polymer membrane, which contains a polymer compound having a constitutional unit represented by Formula I as a constitutional unit A and a constitutional unit derived from a polyfunctional monomer having a ClogP value of equal to or greater than -0.3 to less than 3.0 as a constitutional unit B, a method for manufacturing the functional polymer membrane, a composition for forming a functional polymer membrane from which the functional polymer membrane is obtained, and a separation membrane module and an ion-exchange device which have the functional polymer membrane.