Polymer Purification Using Veratrole Dilution
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Solution Overview
Problem
Existing methods for purifying polymers, such as polyetherimides and polyethersulfones, face challenges in removing residual catalysts and salts during devolatilization extrusion, leading to elevated color and haze in polymer pellets, and phase separation issues during filtration, which are not effectively resolved at temperatures above 100°C.
Innovation Solution
The method involves diluting a mixture of solvents with veratrole to maintain the polymer in a substantially dissolved state at temperatures below 100°C, followed by contacting with an aqueous wash solution and filtering to remove residual catalysts and salts effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the polymerization mixture is filtered at temperatures above 100°C, then the polymer remains dissolved and phase separation is avoided, but the residual catalyst and salt cannot be effectively removed
Solution Approach 1:
The patent changes the temperature parameter from above 100°C to below 100°C (specifically 20-90°C) to simultaneously achieve phase stability and purification effectiveness. This parameter change resolves the contradiction by finding an optimal temperature range where the polymer remains dissolved enough for filtration while enabling effective removal of catalyst and salt
Solution Approach 2:
The patent introduces veratrole as an intermediary solvent to mediate between the polymer and the original solvent system. Veratrole enables the polymer to remain dissolved at lower temperatures (below 100°C) where purification is effective, thus acting as a mediator that allows both phase stability and purification effectiveness to coexist
2Temperature
If the polymerization mixture is diluted and cooled, then phase separation occurs with polymer rich bottom phase and solvent rich upper phase, but this phase change makes filtration and aqueous extraction difficult
Solution Approach 1:
The patent changes the temperature parameter by maintaining it below 100°C (specifically 20-90°C) throughout the process, preventing the phase separation that occurs with cooling. This parameter control ensures the mixture remains homogeneous and easily filterable while still enabling effective purification
Solution Approach 2:
Veratrole acts as an intermediary that prevents phase separation upon cooling. By adding veratrole to the diluted polymerization mixture, the system maintains a single homogeneous phase even at lower temperatures, making filtration and extraction operations straightforward
3Stability of the object's composition
If the polymer rich phase is re-heated and concentrated, then the polymer dissolves back into the solvent, but this process does not effectively remove residual catalyst and salt
Solution Approach 1:
The patent performs purification actions (filtration and aqueous extraction) at lower temperatures (below 100°C) before final concentration. This preliminary purification at conditions where catalyst and salt are effectively removed ensures high purification quality, while the polymer remains in dissolved state throughout the process
Solution Approach 2:
The patent changes the temperature parameter to below 100°C (specifically 20-90°C) for all purification steps, ensuring both the polymer remains dissolved and effective removal of catalyst and salt. This parameter optimization resolves the contradiction by finding conditions where both dissolution and purification effectiveness are achieved simultaneously
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 suppresses phase separation, allows for efficient removal of residual catalysts and salts, and results in purified polymers with improved clarity and stability, enabling effective purification of polyetherimides, polyethersulfones, and their copolymers at lower temperatures.
Implementation Method 1
diluting the first mixture with veratrole to produce a second mixture in which the polymeric material is substantially dissolved at a temperature less than 100° C.
Implementation Method 2
contacting the second mixture with an aqueous wash solution
Implementation Method 3
filtering the second mixture
Data Source
AI summary
A method for purifying a polymer comprising providing a first mixture comprising at least one solvent and at least one polymeric material, diluting the first mixture with veratrole to produce a second mixture in which the polymeric material is substantially dissolved at a temperature less than 100° C., performing at least one step selected from (i) contacting the second mixture with an aqueous wash solution, and (ii) filtering the second mixture.