Polyetherimide Synthesis via Monohalo-Bis(phthalimide) End-Capping
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Solution Overview
Problem
Current methods for manufacturing polyetherimides result in high levels of residual bis(halophthalimide) and chlorine end groups, which degrade the performance of the polymers and are difficult to control, leading to undesirable by-products and properties such as low impact strength and melt flow.
Innovation Solution
A method involving the polymerization of bis(halophthalimide) with alkali metal salts of dihydroxy and monohydroxy aromatic compounds, where the monohydroxy aromatic compound is included in specific mole percentages to control molecular weight and reduce residual content, resulting in polyetherimides with higher molecular weight and improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If excess bis(halophthalimide) is used to control molecular weight, then molecular weight is controlled, but residual unreacted bis(halophthalimide) and chlorine end groups increase
Solution Approach 1:
A monohalo-bis(phthalimide) end-capping agent is introduced as an intermediary substance to react with phenoxide end groups in the growing polymer chains. This mediator allows molecular weight control without using excess bis(halophthalimide), thereby reducing residual unreacted bis(halophthalimide) and chlorine end groups in the final polyetherimide product.
Solution Approach 2:
The invention changes the chemical composition parameter by using a monohalo-bis(phthalimide) end-capping agent with specific structural characteristics (monofunctional with one halo group) instead of the traditional bis(halophthalimide). This parameter change enables stoichiometric control of molecular weight while minimizing harmful residuals.
2Manufacturing precision
If monofunctional compound such as phthalic anhydride is used to control molecular weight, then molecular weight is controlled, but undesirable by-product bis(phthalimide) is formed
Solution Approach 1:
The invention changes the chemical structure parameter of the end-capping agent from phthalic anhydride (which forms bis(phthalimide) by-product) to monohalo-bis(phthalimide) (which contains a reactive halo group). This parameter change ensures that the end-capping agent reacts with phenoxide end groups without forming undesirable bis(phthalimide) by-products, while still achieving molecular weight control.
Solution Approach 2:
The monohalo-bis(phthalimide) serves as an intermediary that performs the dual function of end-capping (controlling molecular weight) and avoiding by-product formation. The reactive halo group allows it to substitute for phthalic anhydride's end-capping function without the harmful side reaction that produces bis(phthalimide).
3Manufacturing precision
If residual bis(halophthalimide), monohalo-bis(phthalimide), and bis(phthalimide) are present, then molecular weight can be controlled, but properties and performance of polyetherimides are degraded
Solution Approach 1:
The monohalo-bis(phthalimide) end-capping agent acts as a superior intermediary that achieves molecular weight control while minimizing all three harmful residuals. By reacting with phenoxide end groups, it prevents the formation of residual monohalo-bis(phthalimide) and bis(phthalimide), and reduces residual bis(halophthalimide), thereby maintaining polyetherimide performance.
Solution Approach 2:
The invention changes the end-capping agent's chemical parameters to optimize the reaction stoichiometry and reactivity. The monohalo-bis(phthalimide) with its specific structure (one reactive halo group per molecule) enables precise control of polymer chain termination, minimizing all harmful residuals while maintaining desired molecular weight and polymer performance.
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 method produces polyetherimides with reduced residual content, enhanced impact strength, and improved melt flow, maintaining high molecular weight and performance while minimizing plate-out during manufacturing.
Implementation Method 1
polymerization of alkali metal salts of dihydroxyaromatic compounds, such as bisphenol A disodium salt (BPA.Na2), with a bis(halophthalimide)
Implementation Method 2
The monohalo-bis(phthalimide) serves as an end-capping agent in the polymerization step by reaction with phenoxide end groups in the growing polymer chains
Implementation Method 3
The monohalo-bis(phthalimide) serves as an end-capping agent in the polymerization step by reaction with phenoxide end groups in the growing polymer chains
Data Source
AI summary
Polyetherimide compositions of formula (1) are described wherein the polyetherimide compositions comprise a polyetherimide comprising a reacted combination of alkali metal salts comprising an alkali metal salt of a dihydroxy aromatic compound and an alkali metal salt of a monohydroxy aromatic compound with a bis(halophthalimide), wherein the alkali metal salt of the monohydroxy aromatic compound is included in an amount of more than 0 and less than 5 mole percent, based on the total moles of the alkali metal salts, and the polyetherimide has a weight average molecular weight greater than or equal to 43,000 Daltons. The polyetherimide exhibits lower levels of chlorine and chlorine end groups, lower levels of bis(halophthalimide) and bis(phthalimide), and low plate-out during manufacturing.