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EP-4536733-B1 - SULFONATED POLY(PHENYLENE ETHER) AND METHODS FOR THE MANUFACTURE THEREOF

EP4536733B1EP 4536733 B1EP4536733 B1EP 4536733B1EP-4536733-B1

Inventors

  • CHOWDHURY, RAJESH
  • LAMBA, Neha
  • MAHESH, Vs
  • Kanjirathadathil, Thomas Paul
  • VUMMITI, Dharmendra

Dates

Publication Date
20260506
Application Date
20230321

Claims (15)

  1. A sulfonated poly(phenylene ether) comprising: repeating units of the formula a degree of sulfonation of 20 to 50% as determined by nuclear magnetic resonance spectroscopy; and a sulfonyl chloride (-SO 2 Cl):sulfonic acid (-SO 3 H) molar ratio of less than or equal to 0.06, wherein the concentrations of sulfonyl chloride and sulfonic acid are detemined by measuring the total concentration of elemental sulfur (S) and chlorine (Cl) using elemental analysis using CHNS and combustion ion chromatography, respectively; wherein in the foregoing formula, Z 1 is independently at each occurrence a sulfonic acid group, a sulfonyl chloride group, halogen, unsubstituted or substituted C 1 - 12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl, C 1 - 12 hydrocarbylthio, C 1 - 12 hydrocarbyloxy, or C 2-12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; Z 2 is independently at each occurrence a sulfonic acid group, a sulfonyl chloride group, hydrogen, halogen, unsubstituted or substituted C 1 - 12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl, C 1 - 12 hydrocarbylthio, C 1 - 12 hydrocarbyloxy, or C 2-12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and x is 1 or 2.
  2. The sulfonated poly(phenylene ether) of claim 1, wherein the sulfonyl chloride (-SO 2 Cl):sulfonic acid (-SO 3 H) molar ratio is less than or equal to 0.05, or less than 0.05, or less than or equal to 0.04, or greater than 0 to 0.04, or 0.001 to 0.04, or 0.01 to 0.04, or 0.02 to 0.04, or 0.03 to 0.04, wherein the concentrations of sulfonyl chloride and sulfonic acid are detemined by measuring the total concentration of elemental sulfur (S) and chlorine (Cl) using elemental analysis using CHNS and combustion ion chromatography, respectively.
  3. The sulfonated poly(phenylene ether) of claim 1 or 2, wherein the sulfonated poly(phenylene ether) comprises 2,6-dimethyl-1,4-phenylene ether repeating units, 2,3,6-trimethyl-1,4-phenylene ether units, 2,5-dimethyl-1,4-phenylene ether repeating units, 2,2',5,5'-tetramethyl-4,4'-dihydroxybiphenyl ether repeating units, 2-methyl-6-phenyl-1,4-phenylene ether repeating units, 2,2'-dimethyl-6,6'-diphenyl-4,4'-dihydroxybiphenyl ether repeating units, 2,6-diphenyl-1,4-phenylene ether repeating units, 2,2',6,6'-tetraphenyl-4,4'-dihydroxybiphenyl ether repeating units, 2,6-dimethoxy-1,4-phenylene ether repeating units, 2,2'-6,6'-tetramethoxy-4,4'-dihydroxybiphenyl ether, 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl ether units, a sulfonated derivative thereof, or a combination thereof.
  4. The sulfonated poly(phenylene ether) of any of claims 1 to 3, wherein the sulfonated poly(phenylene ether) has a number average molecular weight of 60,000 to 100,000 grams per mole, a weight average molecular weight of 130,000 to 200,000 grams per mole, and a dispersity of 1.8 to 2.5, wherein number average molecular weight, weight average molecular weight, and dispersity are determined using gel permeation chromatography in dimethyl formamide relative to polystyrene standards.
  5. The sulfonated poly(phenylene ether) of any of claims 1 to 4, wherein the sulfonated poly(phenylene ether) comprises less than 1 weight percent, or less than 0.75 weight percent, or less than 0.5 weight percent of an oligomer having a molecular weight of less than 1,000 grams per mole, wherein weight percent is based on the total weight of the sulfonated poly(phenylene ether).
  6. The sulfonated poly(phenylene ether) of any of claims 1 to 5, wherein the sulfonated poly(phenylene ether) comprises less than 0.7 weight percent, or less than 0.5 weight percent, or less than 0.4 weight percent of an oligomer having a molecular weight of less than 500 grams per mole, wherein weight percent is based on the total weight of the sulfonated poly(phenylene ether).
  7. The sulfonated poly(phenylene ether) of any of claims 1 to 6, wherein the sulfonated poly(phenylene ether) exhibits an ion exchange capacity of 1.5 to 2.5 milliequivalents per gram of sulfonated poly(phenylene ether), wherein the ion exchange capacity is determined as disclosed in the description.
  8. The sulfonated poly(phenylene ether) of claim 1, comprising sulfonated 2,6-dimethyl-1,4-phenylene ether units; a degree of sulfonation of 20 to 35%; sulfonyl chloride (-SO 2 Cl):sulfonic acid (-SO 3 H) molar ratio of 0.01 to 0.04; and less than 0.5 weight percent of an oligomer having a molecular weight of less than 1,000 grams per mole, wherein weight percent is based on the total weight of the sulfonated poly(phenylene ether); wherein the sulfonated poly(phenylene ether) has a number average molecular weight of 60,000 to 100,000 grams per mole, a weight average molecular weight of 130,000 to 200,000 grams per mole, a dispersity of 1.8 to 2.5, wherein number average molecular weight, weight average molecular weight, and dispersity are determined using gel permeation chromatography in dimethyl formamide relative to polystyrene standards, and an ion exchange capacity of 1.2 to 2.5 milliequivalents per gram of sulfonated poly(phenylene ether), wherein the ion exchange capacity is determined as disclosed in the description.
  9. The sulfonated poly(phenylene ether) of any of claims 1 to 8, wherein the sulfonated poly(phenylene ether) is made by a method comprising dissolving a poly(phenylene ether) in 1,2-dichloroethane to form a mixture; combining a sulfonating agent and a cosolvent, preferably ethyl acetate, with the mixture to form the sulfonated poly(phenylene ether), wherein nitrogen gas is passed over the mixture at a flow rate of greater than or equal to 25 milliliters per minute per mole of sulfonating agent; precipitating the sulfonated poly(phenylene ether); and isolating the precipitated sulfonated poly(phenylene ether).
  10. A method of making the sulfonated poly(phenylene ether) of any of claims 1 to 9, the method comprising: dissolving a poly(phenylene ether) in 1,2-dichloroethane to form a mixture; combining a sulfonating agent and a cosolvent, preferably ethyl acetate, with the mixture to form the sulfonated poly(phenylene ether), wherein nitrogen gas is passed over the mixture at a flow rate of greater than or equal to 30 milliliters per minute per mole of sulfonating agent; precipitating the sulfonated poly(phenylene ether); and isolating the precipitated sulfonated poly(phenylene ether).
  11. The method of claim 10, wherein the dissolving is at a temperature of 30°C to 85°C.
  12. The method of claim 10 or 11, wherein the mixture comprises 1 to 20 wt% of the poly(phenylene ether); and 80 to 99 wt% of the 1,2-dichloroethane,
  13. The method of any of claims 10 to 12, wherein the sulfonating agent and the cosolvent are present in a weight ratio of 1:1.5 to 1.5 to 1, preferably 1:1.1 to 1.1:1.
  14. A membrane comprising the sulfonated poly(phenylene ether) of any of claims 1 to 9.
  15. The membrane of claim 14, wherein the membrane is an ion exchange membrane or a gas separation membrane.

Description

CROSS REFERENCE TO RELATED APPLICATION This application claims priority to and the benefit of European Patent Application No. 22178729.4, filed on June 13, 2022. BACKGROUND Disclosed herein is a sulfonated poly(phenylene ether) and method for the manufacture thereof. Poly(phenylene ether)s are commercially attractive materials because of their unique combination of physical, chemical, and electrical properties. Furthermore, the combination of poly(phenylene ether)s with other polymers or additives provides blends which result in improved overall properties including chemical resistance, high strength, and high flow. As new commercial applications are explored, various sulfonated grades of poly(phenylene ether) materials are desired. Conventional methods for sulfonating poly(phenylene ether) develop heterogeneity with progressive levels of sulfonation, affecting the reaction system making further sulfonation difficult. Sulfonation of poly(phenylene ether) can also lead to degradation of molecular weight and result in the presence of residual reaction byproducts. A method for sulfonation of poly(phenylene ether) to prepare a sulfonated poly(phenylene ether) having a sulfonation degree of 20 to 50% is disclosed in WO2020/254885 A1. It would be desirable to provide an improved process for sulfonating poly(phenylene ether) which can provide high sulfonation levels (e.g., up to 50%) and reduced sulfonyl chloride content. It would be a further advantage to retain high molecular weight polymers after sulfonation, with low oligomer content. SUMMARY A sulfonated poly(phenylene ether) represents an aspect of the present disclosure. The sulfonated poly(phenylene ether) comprises repeating units of the formula a degree of sulfonation of 20 to 50% as determined by nuclear magnetic resonance spectroscopy; and a sulfonyl chloride (-SO2Cl):sulfonic acid (-SO3H) molar ratio of less than or equal to 0.06; wherein in the foregoing formula, Z1 is independently at each occurrence a sulfonic acid group, a sulfonyl chloride group, halogen, unsubstituted or substituted C1-12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl, C1-12 hydrocarbylthio, C1-12 hydrocarbyloxy, or C2-12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; Z2 is independently at each occurrence a sulfonic acid group, a sulfonyl chloride group, hydrogen, halogen, unsubstituted or substituted C1-12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl, C1-12 hydrocarbylthio, C1-12 hydrocarbyloxy, or C2-12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and x is 1 or 2. Another aspect is a method of making the sulfonated poly(phenylene ether), the method comprises dissolving a poly(phenylene ether) in 1,2-dichloroethane to form a mixture; combining a sulfonating agent and a cosolvent, preferably ethyl acetate, with the mixture to form the sulfonated poly(phenylene ether), wherein nitrogen gas is passed over the mixture at a flow rate of greater than or equal to 30 milliliters per minute per mole of sulfonating agent; precipitating the sulfonated poly(phenylene ether); and isolating the precipitated sulfonated poly(phenylene ether). Another aspect is a membrane comprising the sulfonated poly(phenylene ether). Another aspect is a precursor to porous carbon, the precursor comprising the sulfonated poly(phenylene ether). The above described and other features are exemplified by the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings which are exemplary and not limiting. FIG. 1 is a schematic drawing of an embodiment of a method for sulfonating poly(phenylene ether). DETAILED DESCRIPTION Methods have been developed to reliably sulfonate poly(phenylene ether) to degrees of sulfonation ranging from 20 to 50%. Advantageously, the sulfonated poly(phenylene ethers) include low levels of sulfonyl chloride, as well as reduced amounts of oligomeric impurities. The sulfonated poly(phenylene ethers) can retain high molecular weight (e.g., a number average molecular weight of greater than 60,000 grams per mole), with low (e.g., less than 1 weight percent) oligomer content. The sulfonated poly(phenylene ether) having a low sulfonyl chloride content can provide improved ion exchange capacity (IEC). The process is also scalable and allows for the production of poly(phenylene ether) with different sulfonation levels. Homogenous sulfonation is also possible. Accordingly, an aspect of the present disclosure is a sulfonated poly(phenylene ether). The sulfonated poly(phenylene ether) comprises repeating units of the formula wherein in the foregoing formula, Z1 is independently at each occurrence a sulfonic acid group, a sulfonyl chloride group, halogen, unsubstituted or substituted C1-12 hydrocarbyl provided that the hydrocarbyl group is not tertiary hydrocarbyl, C1-12 hydrocarbylthio, C1-12 hydrocarbyloxy, or