Method for preparing a poly(phenylene ether) and poly(phenylene ether) prepared thereby
A method for preparing a poly(phenylene ether) includes feeding air to a continuous flow reactor that contains a reaction mixture including a phenol, a transition metal catalyst, and an organic solvent; and oxidatively polymerizing the reaction mixture at a specified temperature and pressure to form a poly(phenylene ether). The reaction mixture has a residence time in the continuous flow reactor of less than or equal to 30 minutes. Poly(phenylene ether)s prepared by the method and articles including the poly(phenylene ether)s are also described.
1. A method for preparing a poly(phenylene ether), the method comprising:
feeding air to a continuous flow reactor that contains a reaction mixture comprising a phenol, a transition metal catalyst, and an organic solvent; and
oxidatively polymerizing the reaction mixture at a temperature of 20 to 60° C. and a pressure of greater than 150 kPa to form a poly(phenylene ether);
wherein the reaction mixture has a residence time in the continuous flow reactor of less than or equal to 30 minutes.
2. The method of claim 1 , wherein the continuous flow reactor is characterized by a volumetric mass transfer coefficient of 0.1 to 5 sec −1 and a surface area to volume ratio of 10 to 1500 m −1 .
3. The method of claim 1 , wherein the phenol comprises 2,6-dimethylphenol, 2,3,6-trimethylphenol, or a combination thereof.
4. The method of claim 1 , wherein the transition metal catalyst is a copper-amine catalyst.
5. The method of claim 1 , wherein the organic solvent comprises toluene, benzene, xylene, chlorobenzene, ortho-dichlorobenzene, nitrobenzene, trichloroethylene, ethylene dichloride, dichloromethane, chloroform, tetrachloroethane or a combination thereof.
6. The method of claim 1 , wherein the reaction mixture further comprises a dihydric phenol.
7. The method of claim 1 , wherein the reaction mixture further comprises one or more of
a secondary monoamine, a tertiary monoamine, or a combination thereof;
a bromide ion source; and
a phase transfer agent.
8. The method of claim 1 , wherein feeding the air to the reactor is at a flow rate effective to provide a phenol:oxygen molar ratio of 1:1 to 1:1.2.
9. The method of claim 1 , further comprising isolating the poly(phenylene ether) from the reaction mixture.
10. The method of claim 1 , wherein the poly(phenylene ether) has an intrinsic viscosity of 0.04 to 2 deciliter per gram as measured in chloroform at 25° C. using an Ubbelohde viscometer, a polydispersity index of less than 3 determined using gel permeation chromatography using chloroform relative to polystyrene standards, or both.
11. The method of claim 1 , wherein the poly(phenylene ether) has a combined biphenyl and quinone content of less than 0.5 weight percent based on the weight of the phenol used in the oxidative polymerization.
12. A poly(phenylene ether) made by the method of claim 1 .
13. The poly(phenylene ether) of claim 12 , wherein the poly(phenylene ether) has a combined biphenyl and quinone content of less than 0.5 weight percent based on the weight of the phenol used in the oxidative polymerization.
14. An article comprising the poly(phenylene ether) of claim 12 .
15. The method of claim 1 , wherein the continuous flow reactor is characterized by a volumetric mass transfer coefficient of 0.1 to 5 sec −1 .
16. The method of claim 1 , wherein the continuous flow reactor is characterized by a surface area to volume ratio of 10 to 1500 m −1 .