Crosslinked PIM Membranes for Gas Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current microporous polymer membranes for molecular separations face challenges in achieving high permeability and selectivity due to brittleness, poor chemical stability, and limited scalability, with existing crosslinking methods often compromising permeability or stability.
Innovation Solution
A thermal crosslinking process for polymers of intrinsic microporosity (PIMs) is developed, involving heat treatment under controlled oxygen concentrations and temperatures (300-500°C) to create covalently crosslinked polymer networks with enhanced molecular sieving properties, stability, and tailored gas transport characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional polymers are used for membrane separation, then mechanical flexibility and processability are maintained, but gas permeability is limited due to efficient packing and low free volume
Solution Approach 1:
The patent introduces polymers of intrinsic microporosity (PIMs) with permanently microporous structures containing interconnected free volume elements at molecular dimensions. These microporous structures provide high gas permeability while maintaining mechanical flexibility, resolving the contradiction between speed (permeability) and compositional stability (free volume).
Solution Approach 2:
The patent creates crosslinked composite materials combining PIMs polymer matrices with inorganic fillers (zeolites, MOFs, silica nanoparticles). This composite structure enhances both permeability through the microporous network and mechanical stability through the crosslinked framework, simultaneously improving speed and compositional stability.
2Manufacturing precision
If crystalline frameworks like zeolites and MOFs are used, then molecular sieving selectivity is improved, but mechanical brittleness and manufacturing scalability worsen
Solution Approach 1:
The patent merges the advantages of crystalline frameworks (high selectivity) with amorphous polymers (flexibility) by incorporating zeolite, MOF, or COF particles into a polymer matrix. This composite structure provides molecular sieving selectivity from the crystalline fillers while the polymer matrix maintains mechanical flexibility and processability.
Solution Approach 2:
The patent employs flexible polymer matrices and thin film configurations to replace brittle crystalline frameworks. The polymer-based microporous membranes provide comparable molecular sieving performance while maintaining mechanical flexibility and enabling large-scale manufacturing through solution processing.
3Reliability
If crosslinking is applied to enhance stability, then chemical and thermal stability are improved, but gas permeability deteriorates due to reduced free volume
Solution Approach 1:
The patent carefully controls crosslinking parameters (temperature, time, catalyst) to achieve optimal crosslinking density. This controlled approach enhances chemical and thermal stability while preserving sufficient free volume for gas transport, resolving the contradiction between reliability (stability) and speed (permeability).
Solution Approach 2:
The patent employs selective crosslinking strategies where crosslinking is concentrated in specific regions or at controlled densities within the polymer matrix. This local quality approach maintains high chemical stability in crosslinked regions while preserving permeability pathways in uncrosslinked or lightly crosslinked regions.
4Strength
If densely packed polymer structures are used, then mechanical strength is improved, but molecular transport speed decreases due to slow diffusion
Solution Approach 1:
The patent utilizes polymers of intrinsic microporosity with permanently microporous structures containing interconnected free volume elements. These microporous channels provide fast molecular transport pathways while the overall polymer structure maintains mechanical strength through the crosslinked network.
Solution Approach 2:
The patent introduces a hierarchical pore structure with micropores at the molecular dimension and mesopores at the macro dimension. This multi-dimensional pore network accelerates molecular transport through the material while the crosslinked polymer matrix maintains mechanical integrity.
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 process results in membranes with superior selectivity and permeability, surpassing traditional polymer membrane performance limits, while maintaining mechanical flexibility and chemical stability, suitable for various gas and liquid separations.
Implementation Method 1
The polymer chains are thermally rearranged to form a microporous structure, wherein micropores are interconnected with one another through gateways
Implementation Method 2
molecules transport follows a solution-diffusion mechanism, and presents a trade-off between permeability and selectivity
Implementation Method 3
The polymer may be covalently crosslinked
Data Source
AI summary
The present invention provides a process for thermal crosslinking of polymers of intrinsic microporosity (PIMs) by heat treatment of PIMs under controlled oxygen concentration.