High molecular weight poly(2,6-dimethyl-1,4-phenylene ether) and process therefor
First Claim
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1. A method of preparing a poly(2,6-dimethyl-1,4-phenylene ether), comprising:
- oxidatively polymerizing 2,6-dimethylphenol in toluene solvent in the presence of a catalyst comprising copper ion and N,N′
-di-tert-butylethylenediamine to form a reaction mixture comprising a dissolved poly(2,6-dimethyl-1,4-phenylene ether), water, and the catalyst;
wherein the oxidative polymerizing comprises initiating oxidative polymerization in the presence of no more than 10 weight percent of the 2,6-dimethylphenol;
wherein at least 95 weight percent of the 2,6-dimethylphenol is added to the reaction mixture after the initiation of oxidative polymerization and over the course of at least 50 minutes;
wherein the oxidatively polymerizing comprises adding molecular oxygen and 2,6-dimethylphenol to the reaction mixture in a mole ratio of 0.3;
1 to 0.65;
1;
terminating the oxidative polymerization to form a post-termination reaction mixture;
combining a chelant comprising an alkali metal salt of nitrilotriacetic acid with the post-termination reaction mixture to form a chelation mixture comprisingan aqueous phase comprising chelated copper ion, andan organic phase comprising the dissolved poly(2,6-dimethyl-1,4-phenylene ether);
wherein the chelation mixture excludes dihydric phenols and aromatic amines;
maintaining the chelation mixture at a temperature of 40 to 55°
C. for 5 to 100 minutes;
separating the aqueous phase and the organic phase;
wherein the separation is conducted at a temperature of 40 to 55°
C.; and
isolating the poly(2,6-dimethyl-1,4-phenylene ether) from the separated organic phase;
wherein time elapsed between termination of the oxidative polymerization and isolating the poly(2,6-dimethyl-1,4-phenylene ether) is no more than 200 minutes; and
wherein the isolated poly(2,6-dimethyl-1,4-phenylene ether) has a number average molecular weight of at least 18,000 atomic mass units and less than 30 weight percent of molecules having a molecular weight less than 30,000 atomic mass units.
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Abstract
A poly(2,6-dimethyl-1,4-phenylene ether) having a high molecular weight and a reduced content of low molecular weight species can be prepared by a method that includes specific conditions for the oxidative polymerization, chelation, and isolation steps. The poly(2,6-dimethyl-1,4-phenylene ether) is particularly useful for the fabrication of fluid separation membranes.
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Citations
25 Claims
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1. A method of preparing a poly(2,6-dimethyl-1,4-phenylene ether), comprising:
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oxidatively polymerizing 2,6-dimethylphenol in toluene solvent in the presence of a catalyst comprising copper ion and N,N′
-di-tert-butylethylenediamine to form a reaction mixture comprising a dissolved poly(2,6-dimethyl-1,4-phenylene ether), water, and the catalyst;wherein the oxidative polymerizing comprises initiating oxidative polymerization in the presence of no more than 10 weight percent of the 2,6-dimethylphenol; wherein at least 95 weight percent of the 2,6-dimethylphenol is added to the reaction mixture after the initiation of oxidative polymerization and over the course of at least 50 minutes; wherein the oxidatively polymerizing comprises adding molecular oxygen and 2,6-dimethylphenol to the reaction mixture in a mole ratio of 0.3;
1 to 0.65;
1;terminating the oxidative polymerization to form a post-termination reaction mixture; combining a chelant comprising an alkali metal salt of nitrilotriacetic acid with the post-termination reaction mixture to form a chelation mixture comprising an aqueous phase comprising chelated copper ion, and an organic phase comprising the dissolved poly(2,6-dimethyl-1,4-phenylene ether); wherein the chelation mixture excludes dihydric phenols and aromatic amines; maintaining the chelation mixture at a temperature of 40 to 55°
C. for 5 to 100 minutes;separating the aqueous phase and the organic phase;
wherein the separation is conducted at a temperature of 40 to 55°
C.; andisolating the poly(2,6-dimethyl-1,4-phenylene ether) from the separated organic phase; wherein time elapsed between termination of the oxidative polymerization and isolating the poly(2,6-dimethyl-1,4-phenylene ether) is no more than 200 minutes; and wherein the isolated poly(2,6-dimethyl-1,4-phenylene ether) has a number average molecular weight of at least 18,000 atomic mass units and less than 30 weight percent of molecules having a molecular weight less than 30,000 atomic mass units. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
wherein the oxidative polymerizing comprises initiating oxidative polymerization in the presence of 1 to 3 weight percent of the 2,6-dimethylphenol; wherein at least 97 weight percent of the 2,6-dimethylphenol is added to the reaction mixture after the initiation of oxidative polymerization and over the course of 55 to 65 minutes; wherein the oxidatively polymerizing comprises adding molecular oxygen and 2,6-dimethylphenol to the reaction mixture in a mole ratio of 0.3;
1 to 0.5;
1;wherein the oxidatively polymerizing 2,6-dimethylphenol comprises a first stage in which the reaction mixture is cooled to maintain a temperature of 20 to 30°
C., and a second stage in which the reaction mixture is heated to maintain a temperature of 30 to 40°
C.;wherein the method excludes a solvent removal step between the terminating the oxidative polymerization and the isolating the poly(2,6-dimethyl-1,4-phenylene ether); wherein the chelation mixture is maintained at a temperature of 45 to 55°
C. for 40 to 70 minutes;wherein the separating the aqueous phase and the organic phase is conducted at a temperature of 45 to 55°
C.;wherein time elapsed between termination of the oxidative polymerization and isolating the poly(2,6-dimethyl-1,4-phenylene ether) is 30 to 60 minutes; wherein the isolated poly(2,6-dimethyl-1,4-phenylene ether) has a number average molecular weight of 20,000 to 35,000 atomic mass units and 16 to 20 weight percent of molecules having a molecular weight less than 30,000 atomic mass units; and wherein the isolated poly(2,6-dimethyl-1,4-phenylene ether) has a copper concentration of 0.5 to 5 parts per million by weight.
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Specification