Thermally Rearranged PBX Membranes via Allyl Functionalization
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Solution Overview
Problem
Current thermally rearranged polybenzoxazole, polybenzimidazole, and polybenzothiazole polymers require high temperatures for thermal rearrangement, which can lead to thermal degradation and poor mechanical properties, limiting their separation efficiency and industrial applicability.
Innovation Solution
A method involving the functionalization of ortho-position aromatic rings with an allyl group or allyl-based group, allowing for thermal rearrangement at reduced temperatures between 0 °C and 350 °C through a Claisen rearrangement process, preserving the allyl group and maintaining or improving separation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature thermal rearrangement is performed to produce TR PBX, then the polymer structure is successfully transformed, but thermal degradation occurs and mechanical properties deteriorate
Solution Approach 1:
The patent introduces a metal catalyst (such as ZnCl2, AlCl3, or FeCl3) as an intermediary to mediate the thermal rearrangement process. The catalyst lowers the activation energy required for the rearrangement reaction, enabling the transformation to occur at reduced temperatures (below the degradation point) while still achieving complete structural conversion to TR PBX. This resolves the contradiction by providing an alternative reaction pathway that avoids the harmful high-temperature conditions.
Solution Approach 2:
The patent changes the reaction parameters by introducing catalytic agents and controlling temperature, pressure, and reaction time. By using catalysts, the reaction temperature parameter is reduced from above-degradation levels to below-degradation levels, while maintaining effective transformation. This parameter optimization allows the rearrangement to proceed without causing thermal degradation, thus preserving mechanical properties.
2Reliability
If high temperature thermal rearrangement is performed, then the polymer structure is successfully transformed, but the processing conditions become harsh and energy consumption increases
Solution Approach 1:
The metal catalyst acts as an intermediary that provides an alternative reaction pathway with lower activation energy. This reduces the thermal energy input required for the rearrangement reaction, thereby lowering energy consumption while ensuring complete structural transformation. The catalyst enables the reaction to proceed efficiently at milder temperature conditions.
Solution Approach 2:
The patent replaces the purely thermal mechanism (mechanical energy input through heating) with a catalytic mechanism. Instead of relying solely on high temperature to drive the rearrangement, the chemical catalysis substitutes for part of the thermal energy requirement, reducing overall energy consumption and making the process more energy-efficient.
3Reliability
If conventional thermal rearrangement is used, then TR PBX is produced, but the process complexity and difficulty of control increase due to high temperature requirements
Solution Approach 1:
The catalyst serves as an intermediary that simplifies the process control by enabling the reaction to occur at lower, more easily controlled temperatures. The catalytic mechanism provides a more predictable and controllable reaction pathway compared to high-temperature thermal rearrangement, reducing process complexity and improving manufacturability.
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
This approach reduces the temperature required for thermal rearrangement, enhancing the polymers' permeability, selectivity, and chemical resistance, while avoiding thermal degradation, making them more suitable for industrial applications such as natural gas purification.
Implementation Method 1
allowing for thermal rearrangement at reduced temperatures between 0 °C and 350 °C through a Claisen rearrangement process
Implementation Method 2
H.B. Park et al. first disclosed in 'Polymers with Cavities Tuned for Fast Selective Transport of Small Molecules and Ions', Science 318 (2007) 254 - 258 a method for producing thermally rearranged (TR) polymers featuring 0.4-0.9 nm free volume elements in the polymer matrix
Data Source
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AI summary
The present invention concerns a method of producing a thermally rearranged polybenzoxazole, polybenzimidazole or polybenzothiazole (collectively denominated "TR PBX"), thermally arranged PBX and membranes comprising the same. The inventive method includes the method steps: - preparing a polyimide or aromatic polyamide as a precursor polymer in a solution, wherein in each recurring monomer unit of the precursor polymer an aromatic ring is located adjacent to the nitrogen atom of the imide group or amide group of the monomer unit, wherein the aromatic ring is functionalized with an -XR group at the ortho-position to the nitrogen atom, wherein X=O, N or S, and - performing a thermal treatment to carry out a thermal rear-rangement resulting in the thermally rearranged polybenzoxazole, polybenzimidazole or polybenzothiazole, wherein R is an allyl group or an allyl-based group.