Polyether ether ketone membranes side-linked with imidazoles and applications thereof
By grafting imidazole groups onto polyetheretherketone membranes to form a microphase separation structure, the problem of unstable mechanical and separation performance of gas separation membranes under humidity changes is solved, achieving efficient gas transport and mechanical stability over a wide humidity range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHENGZHOU UNIV
- Filing Date
- 2026-04-06
- Publication Date
- 2026-07-10
AI Technical Summary
Existing gas separation membranes struggle to balance mechanical and separation performance when humidity changes. Swelling at high humidity leads to performance degradation, making it impossible to maintain efficient gas transport over a wide humidity range.
The polyetheretherketone (PEEK) membrane with side-linked imidazole groups forms a microphase separation structure by grafting imidazole groups onto the PEEK backbone. The imidazole zinc functional group is responsible for gas transport, while the PEEK backbone provides mechanical stability, decoupling high permeability and high swelling.
Maintaining excellent mechanical and gas separation properties over a wide humidity range, the imidazole zinc complex efficiently transports CO2 at low humidity and inhibits swelling at high humidity, thus preserving the integrity of the membrane structure.
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Figure CN122356464A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of gas separation technology, specifically relating to a polyether ether ketone membrane with side-linked imidazole exhibiting excellent mechanical properties under high humidity water absorption and swelling conditions and high CO2 permeability under low humidity conditions. Background Technology
[0002] Gas separation membrane technology plays a crucial role in carbon dioxide capture. Among these, polymer membranes are one of the most widely used materials due to their low cost, ease of processing, and excellent film-forming properties. However, in practical applications, the carbon dioxide separation performance of membrane materials is generally affected by ambient humidity, with the mechanisms and consequences varying depending on the material type. Polymer membranes based on the principle of enhanced transport exhibit excellent separation performance under sufficient moisture conditions, even surpassing many porous framework materials, and are easier to fabricate on a large scale compared to inorganic membranes. However, these membrane materials, such as water-enhanced transport membranes which are highly dependent on high humidity environments, utilize the hydration reaction of carbon dioxide and the water swelling effect of the polymer network to significantly widen the gas transport channels, thus exhibiting excellent separation performance in a wet state. High flux is only achieved under a highly swollen state (water absorption > 30%), which directly leads to a decrease in the mechanical properties and selectivity of the membrane material. More seriously, the humidity of many industrial gas sources cannot meet the requirements for high membrane swelling, instead causing water loss from the membrane and a sharp decline in membrane performance. The dilemma of this type of membrane lies in the deep entanglement between high performance and high humidity, and the resulting high swelling state, creating an application problem where performance and stability are difficult to achieve simultaneously.
[0003] Therefore, developing a novel membrane material capable of maintaining stable high performance across a wide humidity range (from low to high humidity) without relying on high swelling to maintain gas transport channels is crucial to overcoming current technological bottlenecks. To address these significant needs, an innovative solution is proposed. Unlike homogeneous membranes where performance is closely related to swelling degree, this invention designs and prepares a polyetheretherketone (PEEK) membrane with side-chain-branched imidazole zinc and a clearly defined microphase separation structure. In this structure, the rigid PEEK backbone forms a continuous and stable mechanical framework phase, ensuring excellent dimensional stability and mechanical strength of the membrane under wide humidity conditions. The side-chain-modified imidazole zinc functional groups self-assemble to form discrete, flexible ion transport phase regions, specifically responsible for the efficient recognition and transport of carbon dioxide. Biomimetic materials with metal complexes formed by imidazole groups and central zinc ions have been studied in relevant literature (Chem. Commun., 2012, 48, 1766-1768). This "rigid-flexible, each with its own function" microphase separation structure eliminates the dependence of gas transport on the expansion of the entire polymer matrix, thus successfully decoupling the traditional relationship between "high permeability" and "high swelling." Whether under low humidity conditions, the inherent transport mechanism of the functional phase regions ensures basic performance; or under high humidity conditions, the rigid polyetheretherketone (PEEK) backbone effectively inhibits excessive swelling of the overall membrane, maintaining structural integrity.
[0004] Therefore, it is necessary to develop a polyether ether ketone membrane with side chain modified imidazole zinc complex. Through ingenious molecular design and microphase structure regulation, and with the rigid framework of polyether ether ketone as the key technical support, the inherent contradiction between humidity adaptability and swelling stability of traditional gas separation membranes is solved. This provides a new material platform and feasible path for developing a new generation of high-efficiency, stable, and environmentally adaptable high-performance gas separation membranes. Summary of the Invention
[0005] The purpose of this invention is to provide a polyether ether ketone polymer with side-linked imidazoles and its structural features.
[0006] Another object of the present invention is to provide a polyether ether ketone polymer with the above-mentioned side-linked imidazole that can suppress water absorption and swelling in high humidity environments, thereby maintaining excellent mechanical properties and dimensional stability, and maintaining high carbon dioxide permeability in low humidity environments.
[0007] Therefore, the technical solution of the present invention is as follows:
[0008] A polyetheretherketone (PEEK) film with imidazole-branched side chains, characterized in that it is composed entirely of a PEEK backbone and side chains with imidazole groups. The following is the structural formula of a PEEK polymer with imidazole groups:
[0009]
[0010] In the formula, n is an integer representing the number of repeating polymer units; x is a decimal representing the grafting rate of the imidazole side chain.
[0011] The grafting rate of the polyether ether ketone film with side-linked imidazole is between 55% and 65%.
[0012] The polyetheretherketone (PEEK) film with side-linked imidazole can be prepared by grafting imidazole groups onto the side chains of PEEK.
[0013] The polyetheretherketone (PEEK) membrane with side-linked imidazole is prepared by dissolving PEEK in trifluoromethanesulfonic acid and stirring at 0-10°C for 7-9 hours. The mass-volume ratio of PEEK to trifluoromethanesulfonic acid is 1 g: (9-11) ml.
[0014] The process of preparing the polyether ether ketone membrane with side-linked imidazole involves adding p-chloromethylbenzoic acid to a dissolved polyether ether ketone solution and reacting it at 55-65°C for 20-28 hours. After the reaction, the membrane is precipitated, washed, and dried at 55-65°C for 40-50 hours to obtain polyether ether ketone with carboxyl side groups.
[0015] The process of preparing the polyether ether ketone membrane with side-linked imidazole involves dissolving polyether ether ketone with carboxyl side groups in N-methylpyrrolidone, activating it with a catalyst for 10-20 minutes, adding 1-(3-aminopropyl)imidazolium, reacting at room temperature for 28-48 hours, and then purifying and drying the polyether ether ketone polymer with side-linked imidazole.
[0016] In the preparation process of the polyether ether ketone membrane with side-linked imidazole, the polyether ether ketone polymer with side-linked imidazole is dissolved in N-methylpyrrolidone, zinc acetate is added, and the reaction is stirred for 20-28 hours to coordinate the imidazole groups with zinc ions, thereby obtaining a casting solution of side-chain modified imidazole zinc-modified polyether ether ketone polymer. After purification and drying, the membrane is formed.
[0017] The molar fraction of zinc acetate added during the preparation of the polyether ether ketone membrane with side-linked imidazole is between 5% and 20%.
[0018] The membranes are all prepared by casting and drying a homogeneous casting solution containing polymers. The mass fraction of polymers in the casting solution is between 15% and 25%.
[0019] The imidazole zinc-modified polyether ether ketone membrane is used for gas separation, and is particularly suitable for maintaining high CO2 permeability in low humidity environments, while having better CO2 separation performance in high humidity environments, and maintaining low swelling to preserve mechanical properties.
[0020] This invention provides the structural features and application effects of a polyetheretherketone (PEEK) membrane with side-linked imidazole. Compared with existing technologies, this PEEK membrane with side-linked imidazole exhibits a distinct hydrophilic / hydrophobic phase structure and good mechanical properties. Furthermore, in application, it demonstrates excellent mechanical stability under high humidity conditions and maintains high gas separation performance over a wide humidity range. Attached Figure Description
[0021] Figure 1 The 1H NMR spectrum of the polyether ether ketone with side-linked imidazoles prepared in Example 1 of the present invention;
[0022] Figure 2 SAXS spectra of polyether ether ketone with carboxyl side groups, polyether ether ketone with imidazole side-linked branches, and polyether ether ketone with zinc-modified imidazole side chains prepared in Example 1 of the present invention.
[0023] Figure 3 TGA spectra of polyether ether ketone with carboxyl side groups, polyether ether ketone with imidazole side-linked branches, and polyether ether ketone with zinc-modified imidazole side chains prepared in Example 1 of the present invention.
[0024] Figure 4 Mechanical properties of polyether ether ketone with carboxyl side groups, polyether ether ketone with side-chain-branched imidazole prepared according to Example 1 of the present invention, and side-chain-modified imidazole zinc-modified polyether ether ketone prepared therefrom, in the dry state.
[0025] Figure 5 Water absorption and swelling degree spectra of polyether ether ketone with carboxyl side groups, polyether ether ketone with imidazole side links, and polyether ether ketone with zinc imidazole side chain modification prepared in Example 1 of the present invention.
[0026] Figure 6 Tensile strength spectra of polyether ether ketone with side-chain branched imidazole and polyether ether ketone with side-chain modified imidazole zinc oxide prepared in Example 1 of the present invention as a function of water absorption.
[0027] Figure 7 Grafting rate spectrum of polyether ether ketone with side-linked imidazole prepared in Example 1 of the present invention as a function of reaction time;
[0028] Figure 8 The wet properties of polyether ether ketone with side-linked imidazole prepared in Example 1 of the present invention at different grafting rates are shown in the following graphs.
[0029] Figure 9 The gas separation performance test spectra of polyether ether ketone with side-chain branched imidazole and polyether ether ketone with side-chain modified imidazole zinc prepared in Example 1 of the present invention under high humidity (100%RH).
[0030] Figure 10Gas separation performance test spectra of polyether ether ketone with side-linked imidazole and polyether ether ketone with side-chain modified imidazole zinc prepared in Example 1 of the present invention under low humidity (15.2%RH).
[0031] Figure 11 Long-term stability spectra of gas separation performance of polyether ether ketone with side-chain branched imidazole and polyether ether ketone with side-chain modified imidazole zinc prepared in Example 1 of the present invention under high humidity (100%RH).
[0032] Figure 12 , 13 The carbon dioxide permeation flux and selectivity of polyether ether ketone with side-chain branched imidazole and polyether ether ketone with side-chain modified imidazole zinc prepared in Example 1 of the present invention are measured under heating conditions. Detailed Implementation
[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The embodiments described herein are not intended to limit the present invention in any way. The described embodiments are only some embodiments of the present invention, and not all embodiments.
[0034] All raw materials involved in this invention are not particularly restricted in their source; they are all purchased from the market or prepared according to conventional methods known to those skilled in the art.
[0035] The apparatus involved in this invention is not particularly limited to those commonly used in the field, and those skilled in the art are familiar with its operation and usage.
[0036] Example 1
[0037] 2g of polyetheretherketone (PEEK) was dissolved in 20ml of trifluoromethanesulfonic acid solution. Then, 1.7745g of p-chloromethylbenzoic acid was added to the reactor, and the reaction was carried out with stirring in a 60℃ water bath for 24h. After the reaction, the solution, cooled to room temperature, was slowly poured into deionized water for phase inversion. The resulting carboxyl-side-group PEEK (BzAPEEK) was washed with deionized water until neutral and then dried. It was then fully dissolved in N-methylpyrrolidone solution, followed by activation with a catalyst for 15min. Then, 0.813g of 1-(3-aminopropyl)imidazolium was added to the reactor, and the reaction was carried out with stirring at room temperature for 38h. After the reaction was completed, the solution was poured into a petri dish and dried to obtain PEEK with side-linked imidazolium (IMDPEEK). The solution was then dissolved in N-methylpyrrolidone solution to prepare a homogeneous solution. Zinc acetate (0.119 g) was added, and the mixture was stirred thoroughly for 24 h to obtain a homogeneous solution containing side-chain modified imidazole zinc-modified polyether ether ketone. An appropriate amount of the solution was cast into a petri dish and dried to obtain the side-chain modified imidazole zinc-modified polyether ether ketone polymer (IMD-Zn-II). Figure 1The FTIR spectra of IMDPEK and IMD-Zn-II are shown; Figure 1 The 1H NMR spectrum of the synthesized IMDPEEK is shown. Figure 2 The size comparison of the microphase-separated structures of IMDPEEK and IMD-Zn-II is shown; Figure 3 , 4 Figures 5 and 6 show the thermogravimetric analysis, mechanical property comparison, and water absorption swelling of BzAPEEK, IMDPEK, and IMD-Zn-II, respectively. Figure 6 The mechanical properties of BzAPEEK, IMDPEK, and IMD-Zn-II as a function of water absorption are shown. Figure 7 , 8 The gas permeability of IMDPEEK is compared with that of 60% imidazole grafting rate after 38 h of reaction and with 60% grafting rate. The carbon dioxide permeability at 1 bar is 3087 Barrer and the CO2 / N2 selectivity is 32.9. Figure 9 and 10 The gas properties of IMDPEK and IMD-Zn-II under wet and dry conditions are shown respectively. IMD-Zn-II has a CO2 permeability of 4019 Barrer and a CO2 / N2 selectivity of 77.4 under wet conditions, and a CO2 permeability of 2945 Barrer and a CO2 / N2 selectivity of 55.3 under dry conditions. Figure 11 The long-term stability of IMDPEEK and IMD-Zn-II under wet conditions was demonstrated; Figure 12 and 13 The permeability and selectivity of IMDPEEK and IMD-Zn-II at elevated temperatures are shown respectively.
[0038] Example 2
[0039] A polyether ether ketone (BzAPEEK) with carboxyl side groups was prepared using the same method as in Example 1. It was fully dissolved in an N-methylpyrrolidone solution, followed by activation with a catalyst for 15 min. Then, 0.813 g of 1-(3-aminopropyl)imidazolium was added to the reactor, and the reaction was stirred at room temperature for 28 h. After the reaction was complete, the solution was poured into a petri dish and dried to obtain the polyether ether ketone with side-linked imidazolium (IMDPEEK). Subsequently, a side-chain modified imidazolium zinc-modified polyether ether ketone polymer (IMD-Zn-II) was prepared using the same method as in Example 1. Figure 7 , 8 The gas separation performance of IMDPEEK is shown in comparison with the imidazole group grafting rate of 54% at a reaction time of 38 h and at the 54% grafting rate. The CO2 permeability is 2589 Barrer and the CO2 / N2 selectivity is 28.1.
[0040] Example 3
[0041] A polyether ether ketone (BzAPEEK) with carboxyl side groups was prepared using the same method as in Example 1. It was fully dissolved in an N-methylpyrrolidone solution, followed by activation with a catalyst for 15 min. Then, 0.813 g of 1-(3-aminopropyl)imidazolium was added to the reactor, and the reaction was stirred at room temperature for 48 h. After the reaction was complete, the solution was poured into a petri dish and dried to obtain the polyether ether ketone with side-linked imidazolium (IMDPEEK). Subsequently, a side-chain modified imidazolium zinc-modified polyether ether ketone polymer (IMD-Zn-II) was prepared using the same method as in Example 1. Figure 7 , 8 The gas separation performance of IMDPEEK is shown in comparison with the reaction time of 48 h, the imidazole group grafting rate of 66%, and the grafting rate of 66%. The CO2 permeability is 2318 Barrer and the CO2 / N2 selectivity is 29.9.
[0042] Example 4
[0043] Polyether ether ketone (IMDPEEK) with side-chain-branched imidazole was prepared using the same method as in Example 1. It was then dissolved in an N-methylpyrrolidone solution to prepare a homogeneous solution. Zinc acetate (0.060 g) was added, and the mixture was stirred thoroughly for 24 h to obtain a homogeneous solution containing side-chain-modified imidazole zinc-modified polyether ether ketone. An appropriate amount of the solution was cast into a petri dish and dried to obtain the side-chain-modified imidazole zinc-modified polyether ether ketone polymer (IMD-Zn-I). Figure 2 The dimensions of the microphase-separated structure of IMD-Zn-I are shown; Figure 4 , 5 The mechanical properties and water absorption swelling of IMD-Zn-I are compared respectively; Figure 6 The mechanical properties of IMD-Zn-I as a function of water absorption are shown; Figure 9 and 10 The gas properties of IMD-Zn-I under wet and dry conditions are shown respectively. The CO2 permeability of IMD-Zn-I under wet conditions is 3937 Barrer and the CO2 / N2 selectivity is 62.9. Under dry conditions, the CO2 permeability is 3040 Barrer and the CO2 / N2 selectivity is 46.8. Figure 12 and 13 The permeability and selectivity of IMD-Zn-I under heating are shown respectively.
[0044] Example 5
[0045] Polyether ether ketone (IMDPEEK) with side-chain-branched imidazole was prepared using the same method as in Example 1. It was then dissolved in an N-methylpyrrolidone solution to prepare a homogeneous solution. Zinc acetate (0.239 g) was added, and the mixture was stirred thoroughly for 24 h to obtain a homogeneous solution containing side-chain-modified imidazole zinc-modified polyether ether ketone. An appropriate amount of the solution was cast into a petri dish and dried to obtain the side-chain-modified imidazole zinc-modified polyether ether ketone polymer (IMD-Zn-Ⅲ). Figure 2 The dimensions of the microphase-separated structure of IMD-Zn-Ⅲ are shown; Figure 4 , 5 The mechanical properties and water absorption swelling of IMD-Zn-Ⅲ are compared respectively; Figure 6 The mechanical properties of IMD-Zn-Ⅲ as a function of water absorption are shown. Figure 9 and 10 The gas properties of IMD-Zn-Ⅲ under wet and dry conditions are shown respectively. The CO2 permeability of IMD-Zn-Ⅲ under wet conditions is 3523 Barrer and the CO2 / N2 selectivity is 54.8. Under dry conditions, the CO2 permeability is 2636 Barrer and the CO2 / N2 selectivity is 36.7. Figure 12 and 13 The permeability and selectivity of IMD-Zn-Ⅲ under elevated temperature are shown respectively.
[0046] Finally, it should be noted that the technical solutions of the present invention are not limited to the specific embodiments described above. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. All technical modifications made according to the technical solutions of the present invention fall within the protection scope of the present invention.
Claims
1. A polyetheretherketone film with side-linked imidazole, characterized in that, The entire structure consists of a polyetheretherketone backbone and side chains with imidazole groups. The following is the structural formula of a polyetheretherketone polymer with imidazole groups: In the formula, n is an integer representing the number of repeating polymer units; x is a decimal representing the grafting rate of the imidazole side chain.
2. The polyetheretherketone film with side-linked imidazole as described in claim 1, characterized in that, The grafting rate of the imidazole side chain is between 55% and 65%.
3. The polyetheretherketone film with side-linked imidazole as described in claim 1, characterized in that, It can be prepared by grafting imidazole groups onto the side chains of polyetheretherketone.
4. The polyetheretherketone film with side-linked imidazole as described in claim 1, characterized in that, The preparation process involves dissolving polyether ether ketone in trifluoromethane sulfonic acid and stirring at 0-10℃ for 7-9 hours until dissolved. The mass-volume ratio of polyether ether ketone to trifluoromethane sulfonic acid is 1g:(9-11)ml.
5. The polyetheretherketone film with side-linked imidazole as described in claim 1, characterized in that, The preparation process involves adding p-chloromethylbenzoic acid to a dissolved polyether ether ketone solution and reacting it at 55-65℃ for 20-28 hours. After the reaction is completed, the solution is precipitated, washed, and dried at 55-65℃ for 40-50 hours to obtain polyether ether ketone with carboxyl side groups.
6. The polyetheretherketone film with side-linked imidazole as described in claim 1, characterized in that, The preparation process involves dissolving polyether ketone with carboxyl side groups in N-methylpyrrolidone, activating it with a catalyst for 10-20 minutes, adding 1-(3-aminopropyl)imidazolium, reacting at room temperature for 28-48 hours, and then purifying and drying the product to obtain a polyether ketone polymer with side-linked imidazolium.
7. The polyetheretherketone film with side-linked imidazole as described in claim 1, characterized in that, The preparation process involves dissolving a polyether ether ketone polymer with side-chain-branched imidazole in N-methylpyrrolidone, adding zinc acetate, and stirring for 20-28 hours to coordinate the imidazole groups with zinc ions, thereby obtaining a casting solution of side-chain-modified imidazole zinc-modified polyether ether ketone polymer. After purification and drying, the solution is used to form a film.
8. The polyetheretherketone film with side-linked imidazole as described in claim 1, characterized in that, The molar fraction of zinc acetate added during the preparation process is between 5% and 20%.
9. The polyetheretherketone film with side-linked imidazole as described in claim 1, characterized in that, The membranes are all prepared by casting and drying a homogeneous casting solution containing polymers. The mass fraction of polymers in the casting solution is between 15% and 25%.
10. The application of the imidazole zinc-modified polyetheretherketone film as described in claim 1, characterized in that, The membrane is used for gas separation and is particularly suitable for maintaining high CO2 permeability in low humidity environments, while having better CO2 separation performance in high humidity environments, and maintaining low swelling to preserve mechanical properties.