Poly(arylene ether) fractionation method
View Patent ↗A poly(arylene ether) may be fractionated into higher and lower molecular weight fractions by forming a mixture that includes a poly(arylene ether) starting material, a first solvent that is dichloromethane, bromochloromethane, dibromomethane, or a mixture thereof, and a second solvent different from the first solvent having a Hildebrand solubility parameter of about 16 to about 22 megapascal 1/2 . The mixture separates into fractions containing higher and lower molecular weight poly(arylene ether)s.
1. A method of fractionating a poly(arylene ether), comprising:
forming a mixture comprising
a first poly(arylene ether),
a first solvent selected from the group consisting of dichloromethane, bromochloromethane, dibromomethane, and mixtures thereof, and
a second solvent having a Hildebrand solubility parameter of about 16 to about 22 megapascal 1/2 , with the proviso that the second solvent does not comprise dichloromethane, bromochloromethane, or dibromomethane; and
separating the mixture to yield a soluble fraction comprising a second poly(arylene ether) and an insoluble fraction comprising a third poly(arylene ether).
2. The method of claim 1 , further comprising isolating the second poly(arylene ether) from the soluble fraction.
3. The method of claim 1 , wherein the ratio of the number average molecular weight of the second poly(arylene ether) to the number average molecular weight of the first poly(arylene ether) is about 0.4 to about 0.9.
4. The method of claim 1 , wherein the second poly(arylene ether) has a number average molecular weight of about 1,000 to about 10,000 atomic mass units.
5. The method of claim 1 , wherein the ratio of the intrinsic viscosity of the second poly(arylene ether) to the intrinsic viscosity of the first poly(arylene ether) is about 0.5 to about 0.9.
6. The method of claim 1 , wherein the second poly(arylene ether) has an intrinsic viscosity of about 0.02 to about 0.2 deciliter per gram.
7. The method of claim 1 , wherein said forming a mixture comprises combining the first poly(arylene ether) and the second solvent, and blending the first solvent with the combined first poly(arylene ether) and second solvent.
8. The method of claim 1 , wherein said forming a mixture comprises combining the first poly(arylene ether) and the first solvent, and blending the second solvent with the combined first poly(arylene ether) and first solvent.
9. The method of claim 1 , wherein said forming a mixture comprises blending the first solvent and the second solvent, and blending the first poly(arylene ether) with the combined first solvent and second solvent.
10. The method of claim 1 , wherein the first poly(arylene ether) comprises repeating structural units having the formula
wherein for each structural unit, each Z 1 is independently halogen, unsubstituted or substituted C 1 -C 12 hydrocarbyl with the proviso that the hydrocarbyl group is not tertiary hydrocarbyl, C 1 -C 12 hydrocarbylthio, C 1 -C 12 hydrocarbyloxy, or C 2 -C 12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; and each Z 2 is independently hydrogen, halogen, unsubstituted or substituted C 1 -C 12 hydrocarbyl with the proviso that the hydrocarbyl group is not tertiary hydrocarbyl, C 1 -C 12 hydrocarbylthio, C 1 -C 12 hydrocarbyloxy, or C 2 -C 12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms.
11. The method of claim 1 , wherein the first poly(arylene ether) comprises 2,6-dimethyl-1,4-phenylene ether units, 2,3,6-trimethyl-1,4-phenylene ether units, or a combination thereof.
12. The method of claim 1 , wherein the first poly(arylene ether) is a bifunctional poly(arylene ether) having the structure
wherein z is 0 or 1; each occurrence of x is independently 1 to about 100; each occurrence of Q 1 is independently halogen, unsubstituted or substituted C 1 -C 12 hydrocarbyl with the proviso that the hydrocarbyl group is not tertiary hydrocarbyl, C 1 -C 12 hydrocarbylthio, C 1 -C 12 hydrocarbyloxy, or C 2 -C 12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; each occurrence of Q 2 and R 6 and R 7 is independently hydrogen, halogen, unsubstituted or substituted C 1 -C 12 hydrocarbyl with the proviso that the hydrocarbyl group is not tertiary hydrocarbyl, C 1 -C 12 hydrocarbylthio, C 1 -C 12 hydrocarbyloxy, or C 2 -C 12 halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; each occurrence of R 1 is independently hydrogen or
wherein n is 0 or 1; R 2 is C 1 -C 12 hydrocarbylene; R 2 and R 3 and R 4 are each independently hydrogen or C 1 -C 18 hydrocarbyl; and Y has a structure selected from
wherein each occurrence of R 8 , R 9 , and R 10 is independently selected from hydrogen and C 1 -C 12 hydrocarbyl.
13. The method of claim 1 , wherein the first poly(arylene ether) is a bifunctional poly(arylene ether) having the structure
wherein each occurrence of x is independently 1 to about 50.
14. The method of claim 1 , wherein the first solvent is dichloromethane.
15. The method of claim 1 , wherein the second solvent has a Hildebrand solubility parameter of about 17 to about 21 megapascal 1/2 .
16. The method of claim 1 , wherein the second solvent has a Hildebrand solubility parameter of about 18 to about 20 megapascal 1/2 .
17. The method of claim 1 , wherein the second solvent is an aromatic hydrocarbon solvent selected from the group consisting of benzene, toluene, ethylbenzene, xylenes, anisole, and mixtures thereof.
18. The method of claim 1 , wherein the second solvent is toluene.
19. The method of claim 1 , wherein the second solvent is a halogenated alkane solvent selected from the group consisting of trichloromethane, dichloroethanes, trichloroethanes, tetrachloroethanes, pentachloroethane, hexachloroethane, tribromomethane, dibromoethanes, and mixtures thereof.
20. The method of claim 1 , wherein the second solvent is chloroform.
21. The method of claim 1 , wherein said forming a mixture comprises dissolving at least 80 weight percent of the first poly(arylene ether) in the mixture.
22. The method of claim 1 , wherein said forming a mixture comprises adjusting the mixture to a temperature of about 10° C. to a temperature at which the mixture has a vapor pressure of about 100 kilopascals.
23. The method of claim 1 , wherein the mixture comprises the first poly(arylene ether) and the second solvent in a weight ratio of about 0.2:1 to about 1:1.
24. The method of claim 1 , wherein the mixture comprises the second solvent and the first solvent in a weight ratio of about 1:50 to about 1:1.
25. A method of fractionating a poly(arylene ether), comprising:
forming a mixture comprising a first poly(arylene ether), a first solvent, and a second solvent; wherein the first poly(arylene ether) has an intrinsic viscosity of about 0.1 to about 0.3 deciliter per gram in chloroform at 25° C.; wherein the first solvent is dichloromethane; wherein the second solvent is selected from the group consisting of toluene, chloroform, and mixtures thereof; and wherein at least 90 weight percent of the first poly(arylene ether) is initially dissolved in the mixture;
separating a soluble fraction and an insoluble fraction from the mixture; and
isolating a second poly(arylene ether) from the soluble fraction; wherein the ratio of the intrinsic viscosity of the second poly(arylene ether) to the intrinsic viscosity of the first poly(arylene ether) is about 0.5 to about 0.9.
26. The method of claim 25 , wherein the first poly(arylene ether) is a bifunctional poly(arylene ether) having the structure
wherein each occurrence of x is independently 1 to about 50.
27. A method of fractionating a poly(arylene ether), comprising:
forming a mixture comprising a first poly(arylene ether), a first solvent, and a second solvent; wherein the first poly(arylene ether) has an intrinsic viscosity of about 0.1 to about 0.3 deciliter per gram in chloroform at 25° C.; wherein the first solvent is dichloromethane; wherein the second solvent is selected from the group consisting of toluene and chloroform; wherein the first poly(arylene ether) and the second solvent are present in a weight ratio of about 0.5:1 to about 1:1; and wherein the second solvent and the first solvent are present in a weight ratio of about 1:20 to about 1:2;
separating a soluble fraction and an insoluble fraction from the mixture; and
isolating a second poly(arylene ether) from the soluble fraction; wherein the ratio of the intrinsic viscosity of the second poly(arylene ether) to the intrinsic viscosity of the first poly(arylene ether) is about 0.5 to about 0.8.
28. The method of claim 27 , wherein the first poly(arylene ether) is a bifunctional poly(arylene ether) having the structure
wherein each occurrence of x is independently 1 to about 50.