Polyamides with pendent optical absorbers and related methods

1. A method comprising:

esterifying a hydroxyl-pendent optical absorber with a halogen-terminal aliphatic acid to yield a halogen-terminal alkyl-optical absorber; and

N-alkylating a polyamide with the halogen-terminal alkyl-optical absorber in the presence of a strong base to yield a polyamide having an optical absorber pendent from the polyamide's backbone.

2. The method of claim 1 , wherein the halogen-terminal aliphatic acid is a chloro aliphatic acid or a bromo aliphatic acid.

3. The method of claim 1 , wherein the halogen-terminal aliphatic acid is a C 2 to C 18 halogen-terminal aliphatic acid.

4. The method of claim 1 , wherein the hydroxyl-pendent optical absorber is selected from the group consisting of: 1,2-dihydroxyanthraquinone; carminic acid; 1,3-dihydroxyanthraquinone; 1,4-dihydroxyanthraquinone; 1-hydroxy-4-(p-tolylamino)anthraquinone; 1,8-dihydroxy-3-methoxy-6-methyl anthraquinone; 1,2,5-trihydroxy-6-methylanthracene-9,10-dione; calcein; 6-carboxyfluorescein succinimidyl ester; 6-carboxyfluorescein; 2′,7′-dichloro-3′6′-dihydroxy-3H-spiro[2-benzofuran-1,9′-xanthen]-3-one; fluorescein isothiocyanate; 4′,5′-dibromofluorescein; 5(6)-carboxy-2′,7′-dichlorofluorescein; 4-chloro-3-[(2Z)-2-[1-[5-chloro-4-[[(2Z)-2-[[2-chloro-5-[N-[2-(4-chlorophenoxy)-5-(trifluoromethyl)phenyl]-C-hydroxycarbonimidoyl]phenyl]hydrazinylidene]-3-oxobutanoyl]amino]-2-methylanilino]-1,3-dioxobutan-2-ylidene]hydrazinyl]-N-[2-(4-chlorophenoxy)-5-(trifluoromethyl)phenyl]benzenecarboximidic acid; 2-[(3-carboxy-2-oxidonaphthalen-1-yl)diazenyl]-4-chloro-5-methylbenzenesulfonate di sodium; phenol dyes; 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one; 4,8-diamino-1,5-dihydroxy-9,10-dioxoanthracene-2-sulfonate sodium; 1-amino-4-hydroxy-2-phenoxyanthracene-9,10-dione; 5-oxo-1-(4-sulfonatophenyl)-4-[(4-sulfonatophenyl)diazenyl]-4H-pyrazole-3-carboxylate trisodium; 5-chloro-2-hydroxy-3-[(3-methyl-5-oxo-1-phenyl-4H-pyrazol-4-yl)diazenyl]benzenesulfonate sodium; 2-[(4-hydroxy-9,10-dioxoanthracen-1-yl)amino]-5-methylbenzenesulfonic acid; 3,5,6,8-tetrahydroxy-1-methyl-9,10-dioxo-7-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]anthracene-2-carboxylic acid; and any combination thereof.

5. The method of claim 1 , wherein the polyamide is selected from the group consisting of: polycaproamide, poly(hexamethylene succinamide), polyhexamethylene adipamide, polypentamethylene adipamide, polyhexamethylene sebacamide, polyundecaamide, polydodecaamide, polyhexamethylene terephthalamide, nylon 10,10, nylon 10,12, nylon 10,14, nylon 10,18, nylon 6,18, nylon 6,12, nylon 6,14, nylon 12,12, a semi-aromatic polyamide, an aromatic polyamide, any copolymer thereof, and any combination thereof.

6. The method of claim 1 , wherein the halogen-terminal aliphatic acid is X—(CH 2 ) n —COOH where X is bromo or chloro and n is 1-17.

7. The method of claim 1 , wherein the halogen-terminal aliphatic acid is selected from the group consisting of: bromoacetic acid, chloroacetic acid, 3-bromopropionic acid, 3-chloropropionic acid, 4-bromobutyric acid, 4-chlorobutyric acid, 5-bromovaleric acid, 5-chlorovaleric acid, 6-bromohexanoic acid, 6-chlorohexanoic acid, and any combination thereof.

8. The method of claim 1 , wherein esterifying is at about 0° C. to about 70° C.

9. The method of claim 1 , wherein esterifying is for about 10 minutes to about 24 hours.

10. The method of claim 1 , wherein a molar ratio of the hydroxyl-pendent optical absorber to the halogen-terminal aliphatic acid is about 5:1 to about 1:5.

11. The method of claim 1 , wherein a molar ratio of the halogen-terminal alkyl-optical absorber to the polyamide is about 500:1 to about 10:1.

12. The method of claim 1 , wherein the strong base comprises one or more of:

sodium t-butoxide, potassium t-butoxide, magnesium t-butoxide, calcium t-butoxide, sodium t-amylate, sodium 2-methyl-2-butoxide, alkali metal amides, sodium hydride, lithium hydride, triphenylmethyl lithium, triphenylmethyl sodium, naphthalene sodium, and triphenylmethyl potassium.