Functional ethylene and 1,3-butadiene copolymer

1. An ethylene/1,3-butadiene copolymer comprising: ethylene units, butadiene units, and UD units of cyclic structure of formula (I):

and the copolymer bearing, at one of its chain ends, an alkoxysilyl-containing or a silanol-containing functional group F 1 .

2. The ethylene/1,3-butadiene copolymer according to claim 1 , in which the ethylene units represent at least 50 mol % of all of the monomer units of the copolymer.

3. The ethylene/1,3-butadiene copolymer according to claim 1 , in which the copolymer contains UA, UB, UC, UD units and optional UE units, the UA, UB, UC, UD, and UE units having the following formulas:

UA)

—CH 2 —CH 2 —

according to a molar

percentage of m %

UB)

—CH 2 —CH═CH—CH 2 —

according to a molar

percentage of n %

UC)

—CH 2 —CH(CH═CH 2 )—

according to a molar

percentage of o %

UD)

according to a molar percentage of p %

UE)

according to a molar percentage of q %

m, n, o, p and q ranging from 0 to 100,

m≥50

n+o>0

p>0

q≥0,

the respective molar percentages of m, n, o, p and q being calculated on the basis of the sum of m+n+o+p+q, which is equal to 100.

4. The ethylene/1,3-butadiene copolymer according to claim 3 , in which:

0<o+p≤25

o+p+q≥5

n+o>0

q≥0,

the respective molar percentages of m, n, o, p and q being calculated on the basis of the sum of m+n+o+p+q, which is equal to 100.

5. The ethylene/1,3-butadiene copolymer according to claim 3 , in which q is equal to 0.

6. The ethylene/1,3-butadiene copolymer according claim 1 , in which the functional group F 1 is attached directly via a covalent bond to the terminal unit of the copolymer.

7. The ethylene/1,3-butadiene copolymer according to claim 6 , in which the terminal unit to which the functional group F 1 is directly attached consists of a methylene bonded to an ethylene unit or to a UD unit, the Si atom being bonded to the methylene.

8. The ethylene/1,3-butadiene copolymer according to claim 1 , in which the functional group F 1 is of formula (III-a) or formula (III-b):

Si(OR 1 ) 3-f (R 2 ) f   (III-a)

Si(OH)(R 2 ) 2 ,  (III-b)

in which:

the R 1 symbols, which are identical or different, represent an alkyl,

the R 2 symbols, which are identical or different, represent a hydrogen atom, a hydrocarbyl or a hydrocarbyl substituted by a chemical function F 2 ,

the chemical function F 2 is a primary, secondary or tertiary amine function or a thiol function, the primary or secondary amine or thiol function being protected by a silyl group or being unprotected, and

f is an integer ranging from 0 to 2.

9. The ethylene/1,3-butadiene copolymer according to claim 8 , in which the R 1 symbols represent an alkyl having at most 6 carbon atoms.

10. The ethylene/1,3-butadiene copolymer according to claim 8 , in which the R 2 symbols represent an alkyl having at most 6 carbon atoms or an alkanediyl chain having at most 6 carbon atoms and substituted by the chemical function F 2 .

11. The ethylene/1,3-butadiene copolymer according to claim 8 , in which the alkyl represented by the R 1 and R 2 symbols is a methyl or an ethyl.

12. The ethylene/1,3-butadiene copolymer according to claim 1 , in which the functional group F 1 is dimethoxymethylsilyl, dimethoxyethylsilyl, diethoxymethysilyl, diethoxyethysilyl, 3-(N,N-dimethylamino)propyldimethoxysilyl, 3-(N,N-dimethylamino)propyldiethoxysilyl, 3-aminopropyldimethoxysilyl, 3-aminopropyldiethoxysilyl, 3-thiopropyldimethoxysilyl, 3-thiopropyldiethoxysilyl, methoxydimethylsilyl, methoxydiethylsilyl, ethoxydimethysilyl, ethoxydiethysilyl, 3-(N,N-dimethylamino)propylmethoxymethylsilyl, 3-(N,N-dimethylamino)propylmethoxyethylsilyl, 3-(N,N-dimethylamino)propylethoxymethylsilyl, 3-(N,N-dimethylamino)propylethoxyethylsilyl, 3-aminopropylmethoxymethylsilyl, 3-aminopropylmethoxyethylsilyl, 3-aminopropylethoxymethylsilyl, 3-aminopropylethoxyethylsilyl, 3-thiopropylmethoxymethylsilyl, 3-thiopropylethoxymethylsilyl, 3-thiopropylmethoxyethylsilyl, or 3-thiopropylethoxyethylsilyl, or the amine or thiol function of 3-aminopropyldimethoxysilyl protected by a silyl group, 3-aminopropyldiethoxysilyl, 3-thiopropyldimethoxysilyl, 3-thiopropyldiethoxysilyl, 3-aminopropylmethoxymethylsilyl, 3-aminopropylmethoxyethylsilyl, 3-aminopropylethoxymethylsilyl, 3-aminopropylethoxyethylsilyl, 3-thiopropylmethoxymethylsilyl, 3-thiopropylethoxymethylsilyl, 3-thiopropylmethoxyethylsilyl, or 3-thiopropylethoxyethylsilyl.

13. The ethylene/1,3-butadiene copolymer according to claim 1 , in which the functional group F 1 is dimethylsilanol, diethylsilanol, 3-(N,N-dimethylamino)propylmethylsilanol, 3-(N,N-dimethylamino)propylethylsilanol, 3-aminopropylmethylsilanol, 3-aminopropylethylsilanol, 3-thiopropylethylsilanol, or 3-thiopropylmethylsilanol, or the amine or thiol function of 3-aminopropylmethylsilanol protected by a silyl group, 3-aminopropylethylsilanol, 3-thiopropylethylsilanol, or 3-thiopropylmethylsilanol.

14. The ethylene/1,3-butadiene copolymer according to claim 8 , in which the functional group F 1 is of formula (III-a) in which f is equal to 1.

15. A process for preparing a copolymer defined according to claim 1 , which process comprises the following steps:

a) the copolymerization of a monomer mixture of ethylene and 1,3-butadiene in the presence of a catalytic system comprising an organomagnesium compound and a metallocene comprising the moiety of formula (II)

P 1 (Cp 1 )(Cp 2 )Met  (II)

in which:

Met is a group 4 metal atom or a rare-earth metal atom,

P 1 is a group that bridges the two groups Cp 1 and Cp 2 , and that comprises a silicon or carbon atom,

Cp 1 and Cp 2 , which are identical or different, are components selected from the group consisting of a fluorenyl group, substituted fluorenyl groups, a cyclopentadienyl group, substituted cyclopentadienyl groups, an indenyl group and substituted indenyl groups,

b) the reaction of a functionalizing agent represented by a compound of formula (III), with the copolymer obtained in step a),

Si(Fc 1 ) 4-g (Rc 2 ) g   (III)

the Fc 1 symbols, which are identical or different, representing an alkoxy group or a halogen atom,

the Rc 2 symbols, which are identical or different, representing a hydrogen atom, a hydrocarbon chain or a hydrocarbon chain substituted by a chemical function Fc 2 ,

the chemical function Fc 2 is a primary amine function protected by a silyl group, a secondary amine function protected by a silyl group, a tertiary amine function, or a thiol function protected by a silyl group,

g being an integer ranging from 0 to 2, and

c) optionally a hydrolysis reaction.

16. The process according to claim 15 , in which the metallocene is of formula (II-1)

{P 1 (Cp 1 )(Cp 2 )Met-G} b   (II-1)

in which

Met represents a rare-earth metal atom,

the G symbol denoting a halogen atom X selected from the group consisting of chloride, fluoride, bromide and iodide, or a group comprising the borohydride moiety BH 4 ,

b is equal to 1 or 2.

17. The process according to claim 16 , in which the G symbol denotes chloride or the group of formula (IV)

(BH 4 ) (1+c) -L c -N x   (IV)

in which

L represents an alkali metal atom selected from the group consisting of lithium, sodium and potassium,

N represents a molecule of an ether,

x is equal to or greater than 0,

c, an integer, is equal to or greater than 0.

18. The process according to claim 15 , in which the Met symbol represents a neodymium atom.

19. The process according to claim 15 , in which P 1 denotes the SiMe 2 group.

20. The process according to claim 15 , in which Cp 1 and Cp 2 are identical and are selected from the group consisting of indenyl groups substituted at position 2, substituted fluorenyl groups and the fluorenyl group.

21. The process according to claim 15 , in which Cp 1 is different from Cp 2 , Cp 1 is selected from the group consisting of substituted fluorenyl groups and the fluorenyl group, and Cp 2 is selected from the group consisting of cyclopentadienyl groups substituted at least at positions 2 & 5, indenyl groups substituted at least at position 2, substituted fluorenyl groups and the fluorenyl group.

22. The process according to claim 15 , in which Cp 1 and Cp 2 each represent a substituted fluorenyl group or a fluorenyl group.

23. The process according to claim 15 , in which the metallocene is selected from the group of metallocenes consisting of [Me 2 SiFlu 2 Nd(μ-BH 4 ) 2 Li(THF)} 2 ], [Me 2 SiFlu 2 Nd(μ-BH 4 )(THF)], [Me 2 SiFlu 2 Nd(μ-BH 4 )], [Me 2 Si(2-MeInd) 2 Nd(μ-BH 4 )], [Me 2 Si(C 5 Me 4 )(Flu)Nd(μ-BH 4 )], [Me 2 SiFlu 2 Nd(μ-BH 4 ) 2 Li(THF)], [Me 2 SiFlu 2 Nd(μ-BH 4 )(THF)} 2 ] and [Me 2 SiFlu 2 Nd(Cl)],

the Flu symbol representing the fluorenyl group C 13 H 8 , the Ind symbol representing the indenyl group, the 2-MeInd symbol representing the indenyl group substituted by a methyl at position 2.

24. The process according to claim 15 , in which the metallocene is of formula (IV-3a), (IV-3b), (IV-3c), (IV-3d) or (IV-3e)

[{Me 2 SiFlu 2 Nd(μ-BH 4 ) 2 Li(THF)}2]  (IV-3a)

[Me 2 SiFlu 2 Nd(μ-BH 4 ) 2 Li(THF)]  (IV-3b)

[Me 2 SiFlu 2 Nd(μ-BH 4 )(THF)]  (IV-3 c)

[{Me 2 SiFlu 2 Nd(μ-BH 4 )(THF)}2]  (IV-3d)

[Me 2 SiFlu 2 Nd(μ-BH 4 )],  (IV-3 e)

the Flu symbol representing the fluorenyl group C 13 H 8 .

25. The process according to claim 15 , in which the organomagnesium compound is a dialkylmagnesium compound or an alkylmagnesium halide.

26. The process according to claim 15 , in which at least one of the Fc′ symbols represents an alkoxy group.

27. The process according to claim 15 , in which at least two of the Fc′ symbols represent an alkoxy group.

28. The process according to claim 15 , in which at least three of the Fc′ symbols represent an alkoxy group.

29. The process according to claim 15 , in which the alkoxy group is a methoxy or an ethoxy.

30. The process according to claim 15 , in which the Rc 2 symbols represent an alkyl having at most 6 carbon atoms or an alkanediyl chain having at most 6 carbon atoms and substituted by the chemical function Fc 2 .

31. The process according to claim 30 , in which the alkyl having at most 6 carbon atoms is methyl or ethyl.

32. The process according to claim 15 , in which the silyl group is a trimethylsilyl or tert-butyldimethylsilyl.

33. The process according to claim 15 , in which the functionalizing agent is dimethoxydimethylsilane, diethoxydimethylsilane, dimethoxydiethylsilane, diethoxydiethylsilane, (N,N-dimethyl-3-aminopropyl)methyldimethoxysilane, (N,N-dimethyl-3-aminopropyl)methyldiethoxysilane, (N,N-dimethyl-3-aminopropyl)ethyl-dimethoxysilane, (N,N-dimethyl-3-aminopropyl)ethyldiethoxysilane, 3-methoxy-3,8,8,9,9-pentamethyl-2-oxa-7-thia-3,8-di siladecane, trimethoxymethylsilane, triethoxymethylsilane, trimethoxyethylsilane, triethoxyethylsilane, (N,N-dimethylaminopropyl)trimethoxysilane, (N,N-dimethylaminopropyl)triethoxysilane, (N-(3-trimethoxysilyl)propyl)-N-(trimethylsilyl)silanamine, (N-(3-triethoxysilyl)propyl)-N-(trimethylsilyl)silanamine, or 3,3-dimethoxy-8,8,9,9-tetramethyl-2-oxa-7-thia-3,8-disiladecane.