ABAC Tetrablock Polymer Membranes for Ultrafiltration
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Solution Overview
Problem
Conventional ultrafiltration (UF) membranes manufactured by non-solvent-induced phase separation (NIPS) have limited selectivity due to a broad distribution of surface pores, while track-etching methods produce membranes with high selectivity but low permeability, necessitating the development of polymers that can achieve both narrowly dispersed surface pores and negligible resistance to hydrodynamic flow.
Innovation Solution
A tetrablock polymer with the formula ABAC, where A is a glassy block, B is a rubbery block, and C is a hydrophilic block, is used to create membranes with pores of average diameters between 15 nm to 50 nm, and these membranes are further enhanced by incorporating an ionic liquid within the pores to form supported ionic liquid membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-solvent-induced phase separation (NIPS) is used to manufacture UF membranes, then the membranes have high permeability, but they exhibit limited selectivity due to broad distribution of surface pores
Solution Approach 1:
The patent uses block copolymer composition parameters (glassy/rubbery/hydrophilic block ratios) and processing parameters (non-solvent concentration, immersion time) to control phase separation behavior, achieving narrow pore distribution while maintaining high permeability through precise parameter optimization
Solution Approach 2:
The patent employs composite block copolymer structures combining glassy blocks (for mechanical strength), rubbery blocks (for flexibility), and hydrophilic blocks (for pore formation and selectivity), creating membranes that simultaneously achieve high permeability and narrow pore distribution
2Manufacturing precision
If track-etching method is used to manufacture UF membranes, then the membranes have high selectivity with narrowly dispersed surface pores, but they exhibit low permeability
Solution Approach 1:
The patent optimizes block copolymer molecular weight, composition ratios, and processing conditions to control pore size and distribution, achieving narrow pore distribution similar to track-etching while maintaining high permeability through self-assembled mesoporous structures
Solution Approach 2:
The patent creates controlled mesoporous structures through block copolymer self-assembly and water-induced phase separation, forming uniform nanoscale pores that provide both high selectivity (narrow distribution) and high permeability, overcoming the limitations of track-etching methods
3Device complexity
If homopolymer-based membranes are manufactured by NIPS, then the membranes have simple structure, but they have limited selectivity due to broad distribution of surface pores
Solution Approach 1:
The patent transitions from simple homopolymer structures to composite block copolymer structures (ABAC tetrablocks with glassy A, rubbery B, and hydrophilic C blocks), where the multi-block architecture enables controlled self-assembly and water-induced phase separation to form uniform mesoporous structures with narrow pore distribution
4Manufacturing precision
If membranes with narrowly dispersed surface pores are created, then selectivity is improved, but resistance to hydrodynamic flow increases
Solution Approach 1:
The patent creates a hierarchical porous structure with uniform mesopores (15-50 nm) formed through block copolymer self-assembly, where the controlled pore size and distribution provide high selectivity while the interconnected porous network maintains low resistance to hydrodynamic flow
Solution Approach 2:
The patent uses composite block copolymer structures where hydrophilic blocks form selective mesoporous channels that guide water flow, while rubbery blocks provide flexibility to maintain open pore structures under pressure, reducing hydrodynamic resistance while preserving narrow pore distribution
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 resulting membranes exhibit improved mechanical properties, narrow pore distributions, and enhanced permeability, overcoming the trade-offs between selectivity and permeability of traditional UF membranes, while maintaining mechanical integrity under pressure.
Implementation Method 1
block copolymers have emerged as examples of such materials
Implementation Method 2
solvent-nonsolvent interdiffusion, phase separation, and kinetic arrest
Implementation Method 3
incorporating an ionic liquid within the pores to form supported ionic liquid membranes
Data Source
AI summary
Disclosed is a tetrablock polymer including the formula ABAC, wherein A, B and C are each blocks of the polymer, where A is a glassy block; B is a rubbery block; and C is a hydrophilic block. Also, a membrane including any of the disclosed polymers organized to define pores with an average pore diameter of about 15 nm to about 50 nm is disclosed. A supported ionic liquid membrane including any of the disclosed membranes and an ionic liquid within the pores are also disclosed. Methods of forming a membrane and methods of purifying a liquid or gas are disclosed.