Lubricating compositions comprising thermoassociative and exchangeable copolymers

1. A composition resulting from a mixture comprising:

(a) at least one lubricating oil;

(b) at least one statistical copolymer A1 and at least one compound A2 comprising at least two boronic ester functions;

the statistical copolymer A1 resulting from the copolymerization:

(i) of at least one first monomer M1 of general formula (I)

in which:

R 1 is selected from a group formed by —H, —CH 3 and —CH 2 —CH 3 ;

x is an integer ranging from 2 to 18;

y is an integer equal to 0 or 1;

X 1 and X 2 , identical or different, are selected from a group formed by hydrogen, tetrahydropyranyl, methyloxymethyl, ter-butyl, benzyl, trimethylsilyl and t-butyl dimethylsilyl; or

X 1 and X 2 form with the oxygen atoms a bridge of the following formula

in which:

the stars (*) symbolize the bonds to the oxygen atoms;

R′ 2 and R″ 2 , identical or different, are selected from a group formed by hydrogen and a C 1 -C 11 alkyl; or

X 1 and X 2 form with the oxygen atoms a boronic ester of the following formula

in which:

the stars (*) symbolize the bonds to the oxygen atoms;

R″′ 2 is selected from a group formed by a C 6 -C 18 aryl, a C 7 -C 18 aralkyl and C 2 -C 18 alkyl;

(ii) with at least one second monomer M 2 of general formula (II-A):

in which:

R 2 is selected from a group formed by —H, —CH 3 and —CH 2 —CH 3 ; and

R 31 is selected from a group formed by a C 6 -C 18 aryl, a C 6 -C 18 aryl substituted by an R′ 3 , —C(O)—O—R′ 3 ; —O—R′ 3 , —S—R′ 3 and —C(O)—N(H)—R′ 3 group with R′ 3 a C 1 -C 30 alkyl group, wherein the composition resulting from the mixture comprises the statistical copolymer A1 which can be cross-linked to the at least one compound A2 in a thermoreversible manner.

2. The composition according to claim 1 , in which statistical copolymer A1 results from the copolymerization of at least one monomer M1 with at least two monomers M2 having different R 31 groups.

3. The composition according to claim 2 , in which one of the monomers M2 of the statistical copolymer Al has the general formula (II-A1):

in which:

R 2 is selected from a group formed by —H, —CH 3 and —CH 2 —CH 3 ;

R″ 31 is a C 1 -C 14 alkyl group;

and the other monomer M2 of the statistical copolymer A1 has the general formula (II-A2):

in which:

R 2 is selected from a group formed by —H, —CH 3 and —CH 2 —CH 3 ; and

R″′ 31 is a C 15 -C 30 alkyl group.

4. The composition according to claim 1 , in which the compound A2 is a compound of formula (III):

in which:

w 1 and w 2 , identical or different are integers selected between 0 and 1;

R 4 , R 5 , R 6 and R 7 , identical or different are selected from a group formed by hydrogen and a hydrocarbon-containing group having from 1 to 24 carbon atoms; and

L is a divalent bond group and is selected from a group formed by a C 6 -C 18 aryl, a C 6 -C 18 aralkyl and a C 2 -C 24 hydrocarbon-containing chain.

5. The composition according to claim 1 , in which the compound A2 is a statistical copolymer resulting from the copolymerization of at least one monomer M3 of formula (IV):

in which:

t is an integer equal to 0 or 1;

u is an integer equal to 0 or 1;

M and R 8 are divalent bond groups, identical or different, are selected from a group formed by a C 6 -C 18 aryl, a C 7 -C 24 aralkyl and C 2 -C 24 alkyl;

X is a function selected from a group formed by —O—C(O)—, —C(O)—O—, —C(O)—N(H)—, —N(H)—C(O)—, —S—, —N(H)—, —N(R′ 4 )- and —O—with R′ 4 a hydrocarbon-containing chain comprising from 1 to 15 carbon atoms;

R 9 is selected from a group formed by —H, —CH 3 and —CH 2 —CH 3 ;

R 10 and R 11 identical or different selected from a group formed by hydrogen and a hydrocarbon-containing group having from 1 to 24 carbon atoms;

with at least one second monomer M4 of general formula (V):

in which:

R 12 is selected from a group formed by —H, —CH 3 and —CH 2 —CH 3 ; and

R 13 is selected from a group formed by a C 6 -C 18 aryl, a C 6 -C 18 aryl substituted by an R′ 13 , —C(O)—O—R′ 13 ; —O—R′ 13 , —S—R′ 13 and —C(—)—N(H)—R′ 13 group with R ′ 13 a C 1 -C 25 alkyl group.

6. The composition according to claim 5 , in which the chain formed by the sequence of R 10 , M, X and (R 8 ) u groups with u equal to 0 or 1 of the monomer of general formula (IV) has a total number of carbon atoms comprised between 8 and 38.

7. The composition according to claim 5 , in which the side chains of the copolymer A2 have an average length greater than 8 carbon atoms.

8. The composition according to claim 5 , in which the statistical copolymer A2 has a molar percentage of monomer of formula (IV) in the copolymer ranging from 0.25 to 20%.

9. The composition according to claim 5 , in which the statistical copolymer A2 has a number-average degree of polymerization ranging from 50 to 1500.

10. The composition according to claim 1 , in which the side chains of the statistical copolymer A1 have an average length ranging from 8 to 20 carbon atoms.

11. The composition according to claim 1 , in which the statistical copolymer A1 has a molar percentage of monomer M1 of formula (I) ranging in said copolymer from 1 to 30%.

12. The composition according to claim 1 , in which the statistical copolymer A1 has an average degree of polymerization ranging from 100 to 2000.

13. The composition according to claim 1 , in which the lubricating oil is selected from the oils of Group I, Group II, Group III, Group IV, Group V of the API classification and a mixture thereof.

14. The composition according to claim 1 , further comprising a functional additive selected from a group formed by detergents, anti-wear additives, extreme-pressure additives, additional antioxidants, polymers improving the viscosity index, pour point improvers, anti-foaming agents, corrosion inhibitors, thickeners, dispersants, friction modifiers and mixtures thereof.

15. The composition according to claim 1 , in which a mass ratio between the statistical copolymer A1 and the compound A2 (ratio A1/A2) ranges from 0.001 to 100.

16. The composition according to claim 1 , in which a sum of masses of the statistical copolymer A1 and of the compound A2 ranges from 0.5 to 20% with respect to a total mass of the lubricating composition and a mass of lubricating oil ranges from 80% to 99.5% with respect to the total mass of the lubricating composition.

17. A stock composition resulting from mixing:

(a) at least one statistical copolymer A1;

(b) at least one compound A2 comprising at least two boronic ester functions; and

(c) at least one functional additive selected from a group formed by the detergents, anti-wear additives, extreme-pressure additives, antioxidants, polymers improving the viscosity index, pour point improvers, anti-foaming agents, thickeners, dispersants, friction modifiers and mixtures thereof;

the statistical copolymer A1 resulting from the copolymerization

(i) of at least one first monomer M1 of general formula (I)

in which:

R 1 is selected from a group formed by —H, —CH 3 and —CH 2 —CH 3 ;

x is an integer ranging from 2 to 18;

y is an integer equal to 0 or 1;

X 1 and X 2 , identical or different, are selected from a group formed by hydrogen, tetrahydropyranyl, methyloxymethyl, ter-butyl, benzyl, trimethylsilyl and t-butyl dimethylsilyl;

or

X 1 and X 2 form with the oxygen atoms a bridge of the following formula

in which:

the stars (*) symbolize the bonds to the oxygen atoms;

R′ 2 and R″ 2 , identical or different, are selected from a group formed by hydrogen and a C 1 -C 11 alkyl;

or

X 1 and X 2 form with the oxygen atoms a boronic ester of the following formula

in which:

the stars (*) symbolize the bonds to the oxygen atoms;

R″′ 2 is selected from a group formed by a C 6 -C 18 aryl, a C 7 -C 18 aralkyl and C 2 -C 18 alkyl;

(ii) with at least one second monomer M 2 of general formula (II-A):

in which:

R 2 is selected from a group formed by —H, —CH 3 and —CH 2 —CH 3 ; and

R 31 is selected from a group formed by a C 6 -C 18 aryl, a C 6 -C 18 aryl substituted by an R′ 3 , —C(O)—O—R′ 3 ; —O—R′ 3 , —S—R′ 3 and —C(O)—N(H)—R′ 3 group with R′ 3 a C 1 -C 30 alkyl group, wherein the stock composition resulting from the mixture comprises the statistical copolymer A1 which can be cross-linked to the at least one compound A2 in a thermoreversible manner.

18. The composition according to claim 1 , wherein the viscosity increases when the temperature increases.

19. The composition according to claim 4 , in which the compound A2 is compound A2-1 having the structure:

20. The composition according to claim 5 , in which monomer M3 of formula (IV) is compound A2-2 having the structure: