Cellulosic Membranes with Block Copolymers for Hydrophilicity

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Solution Overview

Problem

Porous cellulosic polymer membranes face challenges in reproducibility, stability, and pore clogging when attempting to modify surface properties such as hydrophilicity and incorporation of reactive functionalities or charged groups for improved chemical resistance and mechanical strength.

Innovation Solution

The use of specific copolymers, including polyglycerol and allyl glycidyl ether-based block copolymers, which can be tailored for hydrophilicity and charged groups, adhering strongly to cellulosic materials and allowing for crosslinking, thereby enhancing membrane surface and bulk properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If hydrophilic monomers are grafted to membrane surfaces or water soluble polymers are coated on membranes, then hydrophilicity is improved, but reproducibility and stability deteriorate

Engineering Contradiction:

ImprovehydrophilicityVSAvoidreproducibility and stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The copolymer is designed with pre-formed hydrophilic blocks (polyglycerol and poly(allyl glycidyl ether)) that are incorporated into the membrane structure before use. This preliminary incorporation of hydrophilic functionality eliminates the need for subsequent surface modification steps, ensuring consistent and reproducible hydrophilic properties while maintaining structural stability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention uses a composite block copolymer structure combining hydrophobic poly(ether sulfone) blocks with hydrophilic polyglycerol and poly(allyl glycidyl ether) blocks. This composite structure integrates both hydrophobic and hydrophilic properties within a single material, achieving stable and reproducible membrane performance without the variability associated with surface coating methods.

Inventive Principle:

Principle #40Composite materials

2Strength

If reactive functionalities and charged groups are incorporated into membranes, then chemical resistance and mechanical strength are improved, but pore clogging occurs

Engineering Contradiction:

Improvemechanical strength and chemical resistanceVSAvoidpore clogging

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The copolymer structure localizes reactive functionalities and charged groups within specific blocks (polyglycerol and poly(allyl glycidyl ether)) rather than distributing them throughout the entire membrane structure. This localized placement allows reactive groups to provide chemical resistance and mechanical strength while the block structure prevents excessive accumulation that would cause pore clogging.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention maintains a porous membrane structure using the block copolymer framework, where the hydrophobic poly(ether sulfone) blocks provide structural integrity and the hydrophilic blocks create controlled porosity. This porous architecture allows reactive functionalities to be present without blocking pores, as the block copolymer morphology ensures open pore pathways are maintained.

Inventive Principle:

Principle #31Porous materials

3Object-affected harmful factors

If copolymers are used to tailor hydrophilicity and charged groups, then membrane properties are improved, but extractables increase

Engineering Contradiction:

Improvehydrophilicity and chemical resistanceVSAvoidextractables

Core Design Contradiction:

Object-affected harmful factorsVSLoss of substance

Solution Approach 1:

Instead of using small molecule additives or surface coatings that can be extracted, the invention inverts the approach by incorporating hydrophilic and reactive functionalities directly into the polymer backbone structure. The block copolymer architecture ensures these functional groups are covalently bonded and structurally integrated, preventing extraction while maintaining the desired properties.

Inventive Principle:

Principle #13The other way round (Inversion)

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 described copolymers effectively improve the hydrophilicity and chemical resistance of porous membranes, reducing extractables and enhancing mechanical strength, while maintaining low extractables and stability.

Implementation Method 1

The copolymers interact strongly with and adhere strongly to cellulosic materials

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

The copolymers are amenable to crosslinking through their hydroxy groups and the allyl groups

Methodology Applied

Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 3

block A is a hydrophilic polymeric segment... it is possible to readily tailor the hydrophilicity... on the membrane as desired

Methodology Applied

Scientific EffectHydrophilicity: Hydrophile

Data Source

PatentEP2977100B1Membranes comprising cellulosic material and hydrophilic block copolymer

Publication Date: 2020.07.29 PALL CORP

AI summary

Disclosed is a porous membrane comprising a cellulosic material and a copolymer of the formula: A-B-A (I) or A-B (II), wherein block A, for example, polyglycerol, a polymer of allyl glycidyl ether, or a copolymer of glycidol and allyl glycidyl ether, or a polymer of allyl glycidyl ether or a copolymer of glycidol and allyl glycidyl ether wherein one or more allyl groups having been replaced by hydrophilic groups. Also disclosed is a method for preparing such a membrane.