High molecular weight poly(2,6-dimethyl-1,4-phenylene ether) and process therefor

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 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.;
• 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.