Poly(phenylene ether) copolymer compositions and associated methods and articles

1. A composition comprising:

a poly(phenylene ether) copolymer derived from monomers comprising 2-methyl-6-phenylphenol and a dihydric phenol; and

a non-halogenated solvent;

wherein the monomers comprise, based on the total weight of monomers, less than 0.5 weight percent of monohydric phenols having identical substituents in the 2- and 6-positions of the phenolic ring; and

wherein the copolymer has an absolute number average molecular weight of 1,000 to 10,000 grams/mole.

2. The composition of claim 1 , wherein the copolymer has an absolute number average molecular weight of 1,000 to 5,000 grams/mole.

3. The composition of claim 1 , comprising:

15 to 80 weight percent of the poly(phenylene ether) copolymer; and

20 to 85 weight percent of the non-halogenated solvent,

based on the total weight of the poly(phenylene ether) copolymer and the non-halogenated solvent.

4. The composition of claim 1 , wherein the dihydric phenol has the structure:

wherein each occurrence of R 1 and R 2 and R 3 and R 4 is independently hydrogen, halogen, unsubstituted or substituted C 1 -C 12 hydrocarbyl provided 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; z is 0 or 1; and Y is:

wherein each occurrence of R 5 -R 8 is independently hydrogen, C 1 -C 12 hydrocarbyl, or C 1 -C 6 hydrocarbylene wherein the two occurrences of R 5 collectively form a C 4 -C 12 alkylene group.

5. The composition of claim 4 , wherein z is 1.

6. The composition of claim 1 , wherein the dihydric phenol comprises 2,2-bis(3,5-dimethyl-4-hydroxyphenol)propane.

7. The composition of claim 1 , wherein the copolymer has the structure:

wherein:

R is independently at each occurrence methyl or di(n-butyl)aminomethyl; provided that the copolymer comprises, on average, less than or equal to 0.005 weight percent of di(n-butyl)aminomethyl groups, based on the weight of the copolymer; and

x and y are independently integers from zero to 50, provided that the sum of x plus y is 4 to 53.

8. The composition of claim 7 , wherein the sum of x and y in the copolymer is 8 to 20.

9. The composition of claim 1 , wherein the absolute number average molecular weight is 1,000 to 3,000 grams/mole.

10. The composition of claim 1 , wherein the non-halogenated solvent comprises C 3 -C 8 ketones, C 4 -C 8 N,N-dialkylamides, C 4 -C 16 dialkyl ethers, C 6 -C 12 aromatic hydrocarbons, C 3 -C 6 alkyl alkanoates, C 2 -C 6 alkyl nitriles, C 2 -C 6 dialkyl sulfoxides, or a combination comprising at least one of the foregoing.

11. The composition of claim 1 , wherein the non-halogenated solvent comprises acetone, methyl ethyl ketone, N-methyl-2-pyrrolidone, toluene, or a combination comprising at least one of the foregoing.

12. The composition of claim 11 , wherein the poly(phenylene ether) copolymer has a solubility of at least 100 grams per kilogram, based on the total weight of the copolymer and non-halogenated solvent, at 25° C.

13. The composition of claim 11 , wherein the poly(phenylene ether) copolymer has a solubility of 100 to 700 grams per kilogram, based on the total weight of the copolymer and non-halogenated solvent, at 25° C.

14. A curable composition, comprising a thermoset resin and the composition of claim 1 .

15. The curable composition of claim 14 , wherein the thermoset resin comprises a epoxy resin and the composition is free of coreactive curing agent other than the poly(phenylene ether) copolymer.

16. The curable composition of claim 15 , comprising:

20 to 99 weight percent of the epoxy resin; and

1 to 80 weight percent of the poly(phenylene ether) copolymer,

based on the total weight of the thermoset resin and the poly(phenylene ether) copolymer.

17. A cured composition obtained by heating the curable composition of claim 14 for a time and temperature sufficient to evaporate the non-halogenated solvent and effect curing.

18. A method of forming a composite, comprising:

impregnating a reinforcing structure with the curable composition of claim 14 ;

removing at least a portion of the non-halogenated solvent from the curable composition and effecting partial cure to form a prepreg; and

laminating and curing a plurality of the prepregs.

19. A composite formed by the method of claim 18 .

20. A printed circuit board comprising the composite of claim 19 .