Fluorinated block copolymers derived from nitrile cure-site monomers

1. A curable composition comprising:

a fluorinated block copolymer having

(a) at least one A block, wherein the A block is a semi-crystalline segment comprising repeating divalent monomeric units derived from tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride; and

b) at least one B block, wherein the B block is a segment comprising repeating divalent monomeric units derived from hexafluoropropylene, vinylidene fluoride, and a nitrile-containing cure-site monomer,

wherein the fluorinated block copolymer has a modulus of 0.1 to 2.5 MPa at 100° C. as measured at a strain of 1% and a frequency of 1 Hertz.

2. The curable composition of claim 1 , wherein the nitrile-containing cure-site monomer comprises at least one of: CF 2 ═CFO(CF 2 ) 5 CN, CF 2 ═CFOCF 2 CF(CF 3 )OCF 2 CF 2 CN, CF 2 ═CFOCF 2 CF(CF 3 )OCF 2 CF(CF 3 )CN, CF 2 ═CFOCF 2 CF 2 CF 2 OCF(CF 3 )CN, CF 2 ═CFOCF 2 CF(CF 3 )OCF 2 CF 2 CN, and combinations thereof.

3. The curable composition of claim 1 , wherein the fluorinated block copolymer has a melting point of at least 100 and at most 275° C.

4. The curable composition of claim 1 , wherein the B block is semi-crystalline.

5. The curable composition of claim 1 , wherein the B block is amorphous.

6. The curable composition of claim 1 , wherein the Tg of the A block is greater than 0° C. and less 80° C.

7. The curable composition of claim 1 , wherein the Tg of the B block is less than 0° C.

8. The curable composition of claim 1 , wherein at least one of the A block, the B block, or both the A block and the B block are derived from a bisolefin monomer is of the formula

wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are independently H, C 1 -C 5 alkyl group, or a C 1 -C 5 fluorinated alkyl group; and Z is an alkylene or cycloalkylene C 1 -C 18 radical, which is linear or branched, optionally containing oxygen atoms and optionally fluorinated.

9. The curable composition of claim 1 , wherein the fluorinated block copolymer comprises about 0.05 wt % to about 1 wt % of iodine based on the weight of the fluorinated block copolymer.

10. The curable composition of claim 1 , further comprising a peroxide cure system.

11. The curable composition of claim 1 , wherein the glass transition temperature of the fluorinated block copolymer is less than −20° C.

12. A cured article derived from the curable composition of claim 1 .

13. The cured article of claim 12 , wherein the article is a packer, an o-ring, a seal, a gasket, a hose, or a sheet.

14. The curable composition of claim 1 , wherein the A block comprises repeating divalent monomeric units further derived from at least one of a perfluorovinyl ether monomer, and a perfluoroallyl ether monomer.

15. The curable composition of claim 1 , further comprising a polyol cure system.

16. The curable composition of claim 1 , wherein the at least one B block is at least one of the following:

(i) 45-85 wt % vinylidene fluoride (VDF), 15-45 wt % hexafluoropropylene (HFP), and 0-30 wt % tetrafluoroethylene (TFE);

(ii) 20-30 wt % VDF, 10-30 wt % of a non-fluorinated olefin, 18-27 wt % of HFP, perfluoroallyl ether, or combinations thereof, and 10-30 wt % TFE; or

(iv) 25-65 wt % VDF, 15-60 wt % HFP and optionally at least 0.1 to at most 30 wt % of an additional comonomer.

17. The curable composition of claim 1 , wherein the fluorinated block copolymer has a melting point of at least 100 and at most 200° C.

18. The curable composition of claim 1 , wherein the Tg of the B block is less than −30° C.