Polysulfone Synthesis Using Composite Ionic Liquid Solvent
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Solution Overview
Problem
The existing industrial process for synthesizing polysulfone is lengthy, energy-intensive, and requires high temperatures, leading to low molecular weight products and environmental concerns due to the use of organic solvents, while the application of ionic liquids in nucleophilic substitution polycondensation for polysulfone synthesis has not been reported.
Innovation Solution
A process using a composite ionic liquid as a solvent for reacting bisphenol monomers with a salt forming agent to form bisphenolate, followed by polycondensation with 4,4′-dihalodiphenyl sulfone, significantly shortening reaction times and improving molecular weight, employing zwitterionic and ionic liquids to accelerate reactions and reduce viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the traditional double-feeding method is used for polysulfone synthesis, then the process can be completed in two separate reaction vessels, but the reaction time is extended to 18 hours and energy consumption increases
Solution Approach 1:
The patent combines the salt formation reaction and polycondensation reaction into a single reaction vessel, eliminating the need for double-feeding between two vessels. This merging of processes reduces the total reaction time from 18 hours to a significantly shorter duration and decreases energy consumption by avoiding repeated heating and cooling cycles between separate reactions.
Solution Approach 2:
The patent performs salt formation reaction first to generate bisphenol A sodium salt in situ, then directly proceeds to polycondensation without isolating the intermediate product. This preliminary action of forming the salt in the same vessel prepares the system for the next reaction step, eliminating the need for intermediate handling and reducing overall process time and energy requirements.
2Speed
If the temperature is increased to 160°C for polycondensation, then the reaction proceeds faster, but the polycondensation becomes too violent and requires temperature reduction to 120°C first
Solution Approach 1:
The patent modifies the reaction parameters by using a catalyst and optimizing the temperature profile. Instead of simply heating to 160°C and then cooling to 120°C, the patent employs a controlled temperature increase with catalyst addition that allows the reaction to proceed at higher temperatures without becoming uncontrollably violent, thereby maintaining both speed and reliability.
Solution Approach 2:
The patent introduces a catalyst as an intermediary substance that facilitates the polycondensation reaction. The catalyst enables the reaction to proceed at higher temperatures with better control, mediating between the monomer and polymer formation processes and preventing violent reactions while maintaining high reaction rates.
3Reliability
If water removal is performed for 2.5 to 8.5 hours after salt formation, then hydrolysis side reactions are inhibited, but the total process time is extended
Solution Approach 1:
The patent maintains continuous removal of water throughout the polycondensation process rather than performing a separate, extended water removal step after salt formation. By continuously removing water as the reaction progresses, the patent prevents hydrolysis side reactions while minimizing the total time required, as water removal occurs concurrently with polymerization rather than sequentially.
4Ease of operation
If organic solvent is added in large amounts for after-treatment, then the system viscosity is reduced, but energy is wasted and the environment is contaminated
Solution Approach 1:
The patent extracts and removes the organic solvent from the reaction system after the polycondensation is complete. Instead of adding large amounts of organic solvent for after-treatment, the patent uses a minimal amount during the reaction and then extracts it through filtration or decantation, thereby reducing energy waste and environmental contamination while still achieving the necessary viscosity management for product isolation.
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 process results in polysulfone with higher molecular weight and reduced energy consumption, avoiding environmental issues associated with organic solvents and simplifying the synthesis by eliminating the need for double-feeding, thus enhancing operational safety and efficiency.
Implementation Method 1
the inventors performed an intensive research in the field of polysulfone preparation in order to find a process for preparing polysulfone in a short reaction time... It turned out that the aforementioned object could be achieved by preparing polysulfone in the presence of a composite ionic liquid as the solvent
Implementation Method 2
employing zwitterionic and ionic liquids to accelerate reactions and reduce viscosity
Implementation Method 3
Ionic liquid, which replaces the traditional organic solvent as the reaction medium, has prominent advantages. For example, it is non-volatile, with a negligible vapor pressure and an excellent thermostability
Implementation Method 4
the composite ionic liquid containing: A) at least one zwitterionic liquid... B) at least one ionic liquid... the reaction for forming bisphenolate and the polycondensation are performed in the presence of a composite ionic liquid as the solvent
Data Source
AI summary
The present invention relates to a process for preparing polysulfone, comprising reacting bisphenol monomers with a salt forming agent to form bisphenolate, followed by subjecting the bisphenolate and 4,4′-dihalodiphenyl sulfone to polycondensation to give polysulfone, characterized in that the reaction for forming bisphenolate and the polycondensation are performed in the presence of a composite ionic liquid as the solvent, the composite ionic liquid containing zwitterionic liquid of formula (I) and/or (II) as component A and ionic liquid of formula (III) and/or (IV) as component B, wherein variables are respectively defined in the description of the present invention. The process of the present invention enables a shortened preparation period of polysulfone, particularly a shortened reaction time (including the time of water removal) of the salt forming stage; in addition, the polysulfone thus prepared has an improved molecular weight which is much higher.