Mixed-Matrix Membranes Using Ionic Liquid Interfacial Agent
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Solution Overview
Problem
Current mixed-matrix membranes (MMMs) for CO2/CH4 separation suffer from reduced selectivity and permeability under mixed-gas, high-pressure, and high-temperature conditions due to delamination and plasticization, leading to instability and decreased performance.
Innovation Solution
A new composition incorporating a charged interfacial agent formed by an ionic liquid (IL)-based oligomer with three or more repeated units, combined with a porous solid additive and a polymerizable ionic liquid, enhances the mechanical stability and gas separation performance by creating a graft polymer network resistant to plasticization and swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MMMs are prepared by adding porous inorganic filler to polymer matrix, then CO2/CH4 separation potential is improved, but interfacial adhesion deteriorates leading to poor selectivity and permeability
Solution Approach 1:
The patent introduces an ionic liquid as an interfacial agent that mediates between the inorganic filler and polymer matrix. The ionic liquid contains both inorganic-compatible and organic-compatible functional groups, enabling it to adsorb onto inorganic surfaces while also interacting with the polymer matrix, thus improving interfacial adhesion and eliminating interfacial void spaces.
Solution Approach 2:
The patent creates a three-component composite system consisting of inorganic filler, polymer matrix, and ionic liquid interfacial agent. This composite approach combines the advantages of each component: the inorganic filler provides separation selectivity, the polymer matrix provides mechanical stability, and the ionic liquid provides improved interfacial adhesion and CO2 permeability.
2Reliability
If high zeolite loading is used to enhance selectivity, then CO2/CH4 separation selectivity is improved, but mechanical stability deteriorates producing brittle MMMs
Solution Approach 1:
The ionic liquid acts as a bonding intermediary between zeolite particles and the polymer matrix, creating strong interfacial connections that allow high zeolite loading (up to 50 wt% or more) without compromising mechanical integrity. The ionic liquid's dual compatibility enables it to bridge the inorganic-organic interface effectively.
Solution Approach 2:
The patent changes the chemical and physical parameters of the polymer-zeolite interface by introducing the ionic liquid, which modifies the interfacial energy, adhesion strength, and stress distribution. This allows the system to withstand high zeolite concentrations while maintaining flexibility and mechanical stability.
3Reliability
If PIL-IL-zeolite MMMs are produced by radical cross-linking, then CO2 separation performance is improved, but delamination and plasticization occur under high-pressure and high-temperature conditions
Solution Approach 1:
The patent creates a multi-phase composite structure where the ionic liquid forms a distinct interfacial phase between the cross-linked polymer matrix and zeolite particles. This composite architecture provides both the cross-linked stability needed for high-performance separation and the ionic liquid's resistance to delamination and plasticization under harsh operating conditions.
Solution Approach 2:
The ionic liquid is strategically positioned at the inorganic-organic interface, providing localized protection against delamination and plasticization where these failures most commonly occur. The cross-linking provides bulk structural stability, while the ionic liquid provides interfacial stability, creating different quality zones optimized for different functions.
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 new composition significantly improves CO2/CH4 separation selectivity and permeability, maintaining stability under mixed-gas, high-pressure, and high-temperature conditions, while reducing system costs and extending membrane lifespan.
Implementation Method 1
a polymerizable ionic liquid, preferably a polymerizable ionic liquid monomer
Implementation Method 2
the charged interfacial agent is an ionic liquid (IL)-based oligomer comprising three or more repeated units
Implementation Method 3
Research in membrane gas separation, and in particular in MMMs, is focused on the development of membranes with high permeability and selectivity
Data Source
AI summary
The invention relates to composition comprising: —at least one porous solid additive having a charged surface; —a charged interfacial agent; —a polymerizable ionic liquid monomer; wherein the charged interfacial agent is an ionic liquid (IL)-based oligomer comprising three or more repeated units. The invention also relates to a mixed-matrix membrane formed from the composition and a method of mixed-matrix membrane manufacture.