Crosslinked phenolic compound, method of forming, and polymer composition containing the same

1. A method of forming a crosslinked polyphenol, the method comprising polycondensing

a bio-based phenolic compound comprising at least one phenolic hydroxyl group, with

a crosslinking agent comprising at least two functional groups reactive with the phenolic hydroxyl group, wherein the at least two functional groups are each independently a halogen group, acid halide group, sulfonyl halide group, anhydride group, or a combination comprising at least one of the foregoing,

to provide the crosslinked polyphenol.

2. The method of claim 1 , wherein the bio-based phenolic compound is a condensed tannin, a hydrolysable tannin, or a combination comprising at least one of the foregoing.

3. The method of claim 1 , wherein the bio-based phenolic compound is quercetin, catechin, epicatechin, anthocyanidin, gallic acid, digallic acid, methyl gallate, ellagic acid, hexahydroxydiphenic acid, luteic acid, casuarictin, gallotannin, ellagitannin, or a combination comprising at least one of the foregoing.

4. The method of claim 1 , wherein the crosslinking agent is

a phthaloyl halide of the formula:

a halobenzene of the formula:

or a combination comprising at least one of the foregoing,

wherein, in the formulae,

each R a is the same or different, and is C 1-12 alkyl, C 6-12 aryl, or -A-(C═O)X;

each R e is the same or different, and is C 1-12 alkyl, C 6-12 aryl, or —X;

each A is the same or different, and is O or N;

each X is the same or different, and is a halogen; and

and t are each independently 0 to 4.

5. The method of claim 1 , wherein the crosslinking agent is phthaloyl chloride, dichlorobenzene, trichlorobenzene, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride, 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride), benzophenone-3,3′,4,4′-tetracarboxylic dianhydride, benzene-1,3-disulfonyl chloride, biphenyl-4,4′-disulfonyl chloride, 4,4′-methylenebis(benzenesulfonyl chloride), 9-oxo-9H-fluorene-2,7-disulfonyl dichloride, P,P-dichlorophenylphosphine, dimethylphosphoramidous dichloride, diphenylphosphoramidous dichloride, dichloromethylphosphine, dichloro(phenyl)phosphine sulfide, dimethylphosphoramidous dichloride, trimesoyl chloride, cyanuric chloride, 1,3,5-triphosphinine-2,4,6-chloride, or a combination comprising at least one of the foregoing.

6. The method of claim 1 , wherein the crosslinked polyphenol has

a weight loss of less than or equal to 3 weight percent, as determined by thermogravimetric analysis comprising heating the crosslinked polyphenol from 23 to 235° C. at a rate of 20° C. per minute; and

a char yield of at least 35 weight percent, as determined by thermogravimetric analysis comprising heating the crosslinked polyphenol from 23 to 750° C. at a rate of 20° C. per minute.

7. The method of claim 1 , wherein the bio-based phenolic compound and the crosslinking agent are present in an amount effective to provide a reaction mixture wherein a mole ratio of phenolic hydroxyl groups to functional groups is 0.4:1 to 2:1.

8. The method of claim 1 , wherein the bio-based phenolic compound is disposed on a surface of an inorganic particle comprising a metal hydroxide, a metal oxide, or a combination comprising at least one of the foregoing.

9. A crosslinked polyphenol produced by the method of claim 1 .

10. A polymer composition comprising:

a polymer; and

2 to 30 weight percent of a crosslinked polyphenol, based on the total weight of the polymer and the crosslinked polyphenol, produced by a method comprising polycondensing

a bio-based phenolic compound comprising at least one phenolic hydroxyl group,

with

a crosslinking agent comprising at least two functional groups reactive with the phenolic hydroxyl group, wherein the at least two functional groups are each independently a halogen group, acid halide group, sulfonyl halide group, anhydride group, or a combination comprising at least one of the foregoing, to provide the crosslinked polyphenol.

11. The polymer composition of claim 10 , wherein the bio-based phenolic compound is a condensed tannin, a hydrolysable tannin, or a combination comprising at least one of the foregoing.

12. The polymer composition of claim 10 , wherein the crosslinking agent is

a phthaloyl halide of the formula:

a halobenzene of the formula:

or a combination comprising at least one of the foregoing, wherein, in the formulae,

each R a is the same or different, and is C 1-12 alkyl, C 6-12 aryl, or -A-(C═O)X;

each R e is the same or different, and is C 1-12 alkyl, C 6-12 aryl, or —X;

each A is the same or different, and is O or N;

each X is the same or different, and is a halogen; and

and t are each independently 0 to 4.

13. The polymer composition of claim 10 , wherein the polymer comprises a thermoplastic, a thermoplastic elastomer, an elastomer, a thermoset, or a combination comprising at least one of the foregoing.

14. The polymer composition of claim 10 , further comprising 1 to 40 parts by weight of a secondary flame retardant or a flame retardant synergist.

15. The polymer composition of claim 14 , wherein the secondary flame retardant or the flame retardant synergist comprises an organophosphate ester, a metal di(C 1-12 alkyl)phosphinate, a bis(phenoxy)phosphazene, a melamine flame retardant, a metal hydroxide, a metal oxide, or a combination comprising at least one of the foregoing.

16. The polymer composition of claim 10 , wherein at least a portion of the crosslinked polyphenol is present in the form of particles surface-coated with the crosslinked polyphenol.

17. The polymer composition of claim 10 , having

a heat release capacity of less than or equal to 80 joules/gram-Kelvin, as determined by pyrolysis combustion flow calorimetry; and

a peak heat release rate of less than or equal to 50 watts/gram, as determined by pyrolysis combustion flow calorimetry.

18. A flame-retardant fabric comprising:

a woven or non-woven fabric substrate; and

a coating on a surface of the fabric substrate, the coating comprising the crosslinked polyphenol of claim 1 ,

wherein the bio-based phenolic compound is a condensed tannin, a hydrolysable tannin, or a combination comprising at least one of the foregoing, and

wherein the bio-based phenolic compound and the crosslinking agent are present in an amount effective to provide a reaction mixture wherein a mole ratio of phenolic hydroxyl groups to functional groups is 0.4:1 to 2:1.

19. The flame-retardant fabric of claim 18 , wherein the crosslinking agent is

a phthaloyl halide of the formula:

a halobenzene of the formula:

or a combination comprising at least one of the foregoing, wherein, in the formulae,

each R a is the same or different, and is C 1-12 alkyl, C 6-12 aryl, or -A-(C═O)X;

each R e is the same or different, and is C 1-12 alkyl, C 6-12 aryl, or —X;

each A is the same or different, and is O or N;

each X is the same or different, and is a halogen; and

and t are each independently 0 to 4.

20. The flame-retardant fabric of claim 19 , wherein the coating forms an intumescent char and induces surface crosslinking of a fiber of the substrate upon burning.