Fluoroether unit-based thermostable, low-T

1. A cross-linkable composition, comprising:

i) a fluorinated α,ω-bis(propargyl) oligomer of formula (I):

wherein

m is 1 to 100,

n is 2 to 150, and

p is 0 to 2,

n, m and p being selected such that the fluorinated α,ω-bis(propargyl) oligomer of formula (I) has a number-average molar mass (M n ) of 400 to 25000 as measured by 19 F NMR spectroscopy;

ii) a cross-linking agent of formula (III):

wherein

R 3 is a hydrogen atom, a C 1 -C 6 aliphatic group, or an aromatic group,

Y is a group selected from H, OH, an aromatic group, a C 1 -C 6 aliphatic group, or an O(CH 2 ) s P(O)(OR 4 ) 2 group,

s an integer from 2 to 20,

R 4 being H or a C 1 -C 6 aliphatic group; and

iii) optionally, a fluorinated oligomer comprising two terminal azide (—N 3 ) groups.

2. The cross-linkable composition according to claim 1 , wherein respective molar proportions of oligomers (i) and (iii) and of cross-linking agent (ii) are such that a total number of propargyl (—CH 2 —C≡CH) groups is equal to a total number of azide (—N 3 ) groups.

3. The cross-linkable composition according to claim 1 , wherein Y is OH, OCH 2 CH 2 P(O)(OH) 2 or OCH 2 CH 2 P(O)(OCH 3 ) 2 .

4. The cross-linkable composition according to claim 1 , wherein the fluorinated α,ω-bis(azide) oligomer is represented by the following formula (IV):

N 3 —CHR 1 (CHR 2 ) p —R F —(CHR 2 ) p CHR 1 —N 3   (IV),

wherein:

radical R F is a fluorinated chain,

p is 0 or 1, and

R 1 and R 2 are independently selected from a hydrogen atom, a C 1 -C 6 alkyl and a C 2 -C 6 alkenyl.

5. The cross-linkable composition according to claim 4 , wherein the fluorinated α,ω-bis(azide) oligomer is represented by the formula (V):

wherein:

m′ is 1 to 100,

n′ is 2 to 150, and

p′ is 0 to 2,

n′, m′ and p′ being selected such that the fluorinated α,ω-bis(propargyl) oligomer of formula (I) has a number-average molar mass (M n ) of 400 to 25000; or

the fluorinated α,ω-bis(azide) oligomer is represented by the formula (VI):

N 3 —CHR 1 CHR 2 —(CR a1 R b1 CR c1 R d1 ) n1 — . . . —(CR ai R bi C ci R di ) ni —CF 2 ) 4 —(CR ci R di CR ai R bi ) ni — . . . —(CR c1 R d1 CR a1 R b1 ) n1 —CHR 2 CHR 1 —N 3   (VI),

wherein:

R 1 and R 2 are independently selected from a hydrogen atom, a C 1 -C 6 alkyl and a C 2 -C 6 alkenyl,

i is 1 to 20,

CR a1 R b1 CR c1 R d1 to CR a1 R bi CR ci R di are constitutional moieties, which may be identical or different, derived from monomers independently selected from the following fluorinated olefins: tetrafluoroethylene; vinylidene fluoride; hexafluoropropylene; trifluoroethylene; perfluoro(methyl vinyl ether); 3,3,3-trifluoropropene; 2,3,3,3-tetrafluoropropene; 1,3,3,3-tetrafluoropropene; chlorotrifluoroethylene; bromotrifluoroethylene; iodotrifluoroethylene; 2-chloro-3,3,3-trifluoropropene; vinyl fluoride; perfluoro(ethyl vinyl ether); perfluoro(propyl vinyl ether); 2-bromo-1,1-difluoroethylene; chlorodifluoroethylene; dichlorodifluoroethylene; 1,1,3,3,3-pentafluoropropene; 1,1,2,3,4,4-hexafluoro-1,3-butadiene; 1-propene, 1,1,3,3,3-pentafluoro-2-(trifluoromethyl)-1-propene; and derivatives thereof, and

n 1 to n i are each independently a number selected from 1 to 20.

6. The composition according to claim 1 , wherein p is 1.75.

7. A material, comprising a product of a click-chemistry reaction of the cross-linkable composition according to claim 1 and having at least one glass-transition temperature value of −70° C. or lower.

8. The material according to claim 7 , wherein the material has a decomposition temperature at 10% weight loss (T d 10% ) of 250° C. or higher, in air.

9. The material according to claim 7 , wherein the material has at least one glass-transition temperature value of −80° C. or lower.

10. A process for preparing the material according to claim 7 , the process comprising performing a cross-linking by click chemistry between:

i) a fluorinated α,ω-bis(propargyl) oligomer of formula (I):

wherein:

m is 1 to 100,

n is 2 to 150, and

p is 0 to 2,

n, m and p being selected such that the fluorinated α,ω-bis(propargyl) oligomer of formula (I) has a number-average molar mass (M n ) of 400 to 25000 as measured by 19 F NMR spectroscopy;

ii) a cross-linking agent of formula (III):

wherein:

R 3 is a hydrogen atom, a C 1 -C 6 , aliphatic group, or an aromatic group, and

Y is a group selected from H, OH, an aromatic group, a C 1 -C 6 aliphatic group, an O(CH 2 ) s P(O)(OR 4 ) 2 group,

s an integer from 2 to 20,

R 4 being H or a C 1 -C 6 aliphatic group, notably a methyl, ethyl or isopropyl group; and

iii) optionally, a fluorinated oligomer comprising two terminal azide (—N 3 ) groups.

11. The process according to claim 10 , wherein the cross-linking occurs in the presence of a copper catalyst.

12. An electrical insulator, comprising the material of claim 7 .

13. The electrical insulator according to claim 12 , which is suitable as an encapsulant for electronic cards in on-board systems or power modules, coatings for rotary machines or electric motors, semi-rigid packaging components, wiring.

14. The electrical insulator according to claim 12 , wherein the material has a decomposition temperature at 10% weight loss (T d 10% ) of 250° C. or higher, in air.