COMPOSITIONS WITH THERMAL ASSOCIATIVE AND EXCHANGEABLE COPOLYMERS

Description

Technical field

[0001] The invention relates to a composition resulting from the mixing of at least one polydiol comb copolymer A1, and at least one compound A2 comprising at least two boronic ester functions. Such compositions have very varied rheological properties depending on the proportion of compounds A1 and A2 used. The invention also relates to a composition resulting from the mixing of at least one lubricating oil with such a polymer composition and the use of this composition for lubricating a mechanical part.

[0002] The field of the invention is that of associative and exchangeable polymers and that of lubricants. State of the prior art

[0003] High molecular weight polymers are widely used to increase the viscosity of solutions in many fields, such as the petroleum industry, paper, water treatment, mining, cosmetics, textiles and generally in all industrial techniques using thickened solutions.

[0004] However, these high molecular weight polymers have the disadvantage of exhibiting significant irreversible degradation under mechanical stress compared to the same polymers of smaller sizes. These shear stresses on high molecular weight polymers cause breaks at the level of the macromolecular chains. The polymer thus degraded sees its thickening properties diminish or disappear, and the viscosity of the solutions containing it drops irreversibly. This low shear resistance leads to a degradation of the properties of solutions based on high molecular weight polymers.

[0005] Applications WO2015 / 110642, WO2015 / 110643 and WO2016113229 disclose a composition resulting from the mixture of at least one copolymer A1 resulting from the copolymerization of at least one monomer functionalized by diol functions, and at least one compound A2 comprising at least two boronic ester functions. These compounds can combine, possibly to form a gel, and exchange chemical bonds thermoreversibly. These additives have the advantage of reducing the drop in viscosity of the solution comprising them when the temperature increases. These polymer compositions have very varied rheological properties depending on the proportion of compounds A1 and A2 used. They can also comprise an exogenous compound which allows better control of the combination of the two compounds.

[0006] In particular, these polymer compositions can be added to a lubricating oil to lubricate a mechanical part. These copolymers make it possible to formulate lubricating compositions whose viscosity is better controlled compared to the lubricating compositions of the prior art. In particular, these copolymers, when introduced into a base oil, tend to reduce the viscosity drop of the mixture when the temperature increases.

[0007] Lubricating compositions are compositions applied between the surfaces, particularly metallic surfaces, of moving parts. They reduce friction and wear between two parts in contact and moving relative to each other. They also serve to dissipate some of the thermal energy generated by this friction. Lubricating compositions form a protective film between the surfaces of the parts to which they are applied.

[0008] The compositions used for lubricating mechanical parts generally consist of a base oil and additives. The base oil, particularly of petroleum or synthetic origin, exhibits variations in viscosity when the temperature is varied.

[0009] Indeed, when the temperature of a base oil increases, its viscosity decreases and when the temperature of the base oil decreases, its viscosity increases. However, in hydrodynamic lubrication regime, the thickness of the protective film is proportional to the viscosity, therefore also depends on the temperature. A composition has good lubricating properties if the thickness of the protective film remains substantially constant regardless of the conditions and duration of use of the lubricant.

[0010] In an internal combustion engine, a lubricating composition may be subject to external or internal temperature changes. External temperature changes are due to ambient air temperature variations, such as temperature variations between summer and winter, for example. Internal temperature changes result from the operation of the engine. The temperature of an engine is lower during its start-up phase, especially in cold weather, than during prolonged use. Therefore, the thickness of the protective film may vary in these different situations.

[0011] There is therefore a need for a lubricating composition with good lubricating properties and whose viscosity is not very subject to temperature variations.

[0012] It is known to add viscosity-enhancing additives to a lubricating composition. These additives have the function of modifying the rheological behavior of the lubricating composition. They help promote greater viscosity stability over a temperature range at which the lubricating composition is used. For example, these additives limit the decrease in viscosity of the lubricating composition when the temperature rises, while limiting the increase in viscosity when cold.

[0013] Viscosity-improving additives (or viscosity index-improving additives) ensure good lubrication by limiting the impact on cold viscosity and ensuring a minimum film thickness when hot. Viscosity-improving additives currently used are polymers such as olefin copolymers (OCPs) and polyalkyl methacrylates (PMAs). In general, the contribution of these polymers to viscosity control is greater the higher their molecular weight.

[0014] However, high molar mass polymers have the disadvantage of having low permanent shear strength compared to polymers of the same nature and architecture but of smaller size.

[0015] However, a lubricating composition is subject to significant shear stresses, particularly in internal combustion engines, where the moving surfaces have a very small separation and the pressures exerted on the parts are high. These shear stresses on high molar mass polymers cause breaks in the macromolecular chains. The polymer thus degraded sees its thickening properties reduced, and the viscosity drops irreversibly. This low resistance to permanent shear therefore leads to a degradation of the lubricating properties of the lubricating composition.

[0016] Finally, efforts have been made to develop compositions with better stability to oxidation, in particular better resistance to oxidation by free radicals.

[0017] Document US2011 / 319305 describes comb copolymers comprising olefinic repeating units with a molecular weight greater than 500g / mol and repeating units with a molecular weight less than 500g / mol and their use in hydraulic fluids.

[0018] Document EP0570073 describes a poly(alkyl)acrylate type lubricating oil additive in which certain monomers comprise boron-based functionalities.

[0019] It is indicated in applications WO2015 / 110642, WO2015 / 110643 and WO2016113229 that the A1 diol random copolymers are comb copolymers, i.e. copolymers having a main chain (also called a backbone) and hydrocarbon side chains, optionally hydroxylated, hanging on either side of the main chain. It is noted that the side chains of these copolymers of the prior art are not polymers or oligomers, and that these copolymers are therefore not comb copolymers in the usual sense for a person skilled in the art (IUPAC Commission for Macromolecular Nomenclature, Glossary of Basic Terms in Polymer Science, Recommendations 1996, available at https: / / www.gfp.asso.fr / wp-content / uploads / glossaire.pdf). In reality, these copolymers are rather linear copolymers whose non-polymeric hydrocarbon side chains have an average length ranging from 8 to 20 carbon atoms.

[0020] The compositions described in applications WO2015 / 110642, WO2015 / 110643 and WO2016113229 have very interesting properties, due to their ability to form thermoreversible associations. However, it was desired to further improve these properties, in particular it was sought to reduce the sensitivity of the viscosity of the compositions with respect to temperature, to provide compositions which have better viscosity stability between high temperatures and low temperatures. It was also sought to provide compositions which have a greater amplitude of viscosity modulation.

[0021] Furthermore, it has been observed that under certain conditions, particularly high temperature, the associative behavior of these copolymers decreases. In particular, a decrease in the viscosity index of the lubricating compositions comprising them, a lower resistance to cycling (which can be defined as the succession of sequences of temperature increase and decrease as observed in an engine), leading to a loss of lubricating properties over time, has been observed.

[0022] Also, the applicant set itself the objective of preparing new copolymers having improved properties compared to the copolymers of the prior art.

[0023] This objective is achieved by means of new rheological additives which can combine, possibly to form a gel, and exchange thermoreversibly. Unlike the base oil which becomes more fluid when the temperature increases, the additives of the present invention have the advantage of thickening the medium in which they are dispersed when the temperature increases and retain this advantage at high temperatures, such as up to 150°C. These additives comprise a polydiol comb copolymer A1 (at least part of the side chains of which are of oligomer type) and a compound A2 comprising at least two boronic ester functions. These additives allow a greater amplitude of modulation of the viscosity as a function of the temperature. The lubricating compositions comprising them have a reduced sensitivity of their viscosity with respect to temperature, a greater stability of the viscosity with respect to changes in temperature.This characteristic results from the combined use of two particular compounds, a comb copolymer carrying diol functions and possibly styrenic functions and a compound comprising boronic ester functions.

[0024] It is possible, thanks to the compositions of the invention, to provide lubricating compositions which have good lubricating properties during the starting phases of an engine (cold phase) and good lubricating properties when the engine is operating at its operating temperature (hot phase). Summary of the invention

[0025] The invention relates to a composition resulting from the mixing of at least ∘ a polydiol comb copolymer A1, statistical or gradient, and ∘ a compound A2 comprising at least two boronic ester functions, the polydiol comb copolymer A1 comprising a main chain and side chains, at least a portion of the side chains of the copolymer A1 being composed of oligomers comprising more than 30 carbon atoms which have a degree of polymerization ranging from 5 to 1000.

[0026] The invention also relates to a lubricating composition resulting from the mixing of at least: a lubricating oil, and a composition as defined above and in detail below.

[0027] A method for modulating the viscosity of a lubricating composition is also disclosed, the method comprising at least: the provision of a composition as defined above and detailed in the description below, the mixing of this composition with a lubricating oil.

[0028] According to a preferred embodiment, the side chains composed of oligomers represent from 3 to 95% by mass relative to the total mass of the copolymer A1, preferably from 15 to 95%.

[0029] At least part of the side chains of copolymer A1 is composed of oligomers comprising more than 30 carbon atoms, preferably at least 50 carbon atoms, even better at least 70 carbon atoms.

[0030] According to a further preferred embodiment, the side chains composed of oligomers comprising more than 30 carbon atoms represent from 3 to 95% by mass relative to the total mass of the copolymer A1, preferably from 15 to 95%.

[0031] According to a preferred embodiment, at least a portion of the side chains of the copolymer A1 is composed of oligomers which have a degree of polymerization ranging from 5 to 500, preferably from 5 to 200.

[0032] According to a preferred embodiment, at least a portion of the side chains of the copolymer A1 is composed of oligomers O1 comprising a polyolefin fragment.

[0033] According to a preferred embodiment, the side chains of the copolymer A1 composed of oligomers O1 comprise a polyolefin fragment having from 30 to 500 carbon atoms, preferably from 50 to 400 carbon atoms, even better from 50 to 200 carbon atoms.

[0034] According to a preferred embodiment, the side chains comprising a polyolefin fragment represent from 3 to 85%, preferably from 15 to 70% by mass relative to the total mass of the copolymer A1.

[0035] According to a further preferred embodiment, the oligomers O1 are present in the copolymer A1 in the form of repeating units corresponding to one or more monomers M6 of general formula (IX): in which Q 1 is selected from the group consisting of -H, -CH 3 , and -CH 2 -CH 3 ; Q 2 is selected from a group -Q', -O-Q', -C(O)-O-Q', -OC(O)-Q', -S-(CH 2 ) 2 -C(O)-O-Q', ,-S-Q', -N(H)-C(O)- Q' and -C(O)-N(H)-Q' with Q' is a polyolefin, n represents an integer selected from 0 and 1, A represents a divalent group selected from -A 1 -, -O-(-A 2 -O-)n'-A 1 -, - C(O)-O- (-A 2 -O-)n'-A 1 -, -OC(O)-(-A 2 -O-)n'-A 1 -, -S-(-A 2 -O-)n'-A 1 -, - N(H)-C(O)-(-A 2 -O-)n'- A 1 - and -C(O)-N(H)-(-A 2 -O-)n'-A 1 - with: A 1 is a divalent radical chosen from a C 1 -C 30 alkyl, a C 6 -C 30 aryl, a C 6 -C 30 aralkyl, A 2 is a divalent radical chosen from C 2 -C 4 alkyls, n' is an integer, n' represents 0 or 1.

[0036] According to a preferred embodiment, at least part of the side chains of the copolymer A1 is composed of oligomers O2 comprising repeating units corresponding to monomers M2 of general formula (II): in which: R 2 is selected from the group consisting of -H, -CH 3 and -CH 2 -CH 3 , R 3 is selected from the group consisting of: -C(O)-OR' 3 ; -OR' 3 ; -SR' 3 and -C(O)-N(H)-R' 3 with R' 3 being a C 1 -C 30 alkyl group.

[0037] According to a further preferred embodiment, at least a portion of the oligomers O2 comprises repeating units corresponding to monomers M1 of general formula (I): in which: R 1 is chosen from the group formed by -H, -CH 3 , and -CH 2 -CH 3 ; y is an integer equal to 0 or 1; Y represents a divalent linking group chosen from C 1 -C 20 alkyl chains, optionally comprising one or more ether bridges -O-; X 1 and X 2 , identical or different, are chosen from the group formed by hydrogen, tetrahydropyranyl, methyloxymethyl, tert-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 chosen from the group formed by hydrogen and a C 1 -C 11 alkyl, preferably methyl; 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 the group consisting of a C aryl 6 -C 30 , a C aralkyl 7 -C 30 and a C alkyl 2 -C 30 , preferably a C aryl 6 -C 18 .

[0038] According to a further preferred embodiment, the monomer M1 is chosen from the monomers of formula (Ibis): in which x is an integer ranging from 1 to 18, preferably from 2 to 18.

[0039] According to one embodiment, when a portion of the side chains of the copolymer A1 is composed of oligomers comprising repeating units corresponding to monomers M1 and / or M2, these oligomers have a degree of polymerization ranging from 5 to 500, preferably from 10 to 400, even better from 20 to 200.

[0040] According to a preferred embodiment, when the side chains of the copolymer A1 are composed of oligomers O1 comprising a polyolefin fragment having from 30 to 105 carbon atoms, the repeating units of the copolymer A1 contain more than 5 mol% of monomers M6 of general formula (IX), preferably more than 6 mol% of monomers M6 of general formula (IX), even better more than 6.5 mol% of monomers M6 of general formula (IX).

[0041] According to a preferred embodiment, the main chain of copolymer A1 comprises repeating units corresponding to at least one monomer M2 of general formula (II): in which: R 2 is selected from the group consisting of -H, -CH 3 and -CH 2 -CH 3 , R 3 is selected from the group consisting of: -C(O)-OR' 3 ; -OR' 3 ; -SR' 3 and -C(O)-N(H)-R' 3 with R' 3 being a C 1 -C 30 alkyl group.

[0042] According to a further preferred embodiment, the main chain of the copolymer A1 comprises repeating units corresponding to at least one monomer M1 of general formula (I): in which: R 1 is chosen from the group formed by -H, -CH 3 , and -CH 2 -CH 3 ; y is an integer equal to 0 or 1; Y represents a divalent linking group chosen from C 1 -C 20 alkyl chains, optionally comprising one or more ether bridges -O-; X 1 and X 2 , identical or different, are chosen from the group formed by hydrogen, tetrahydropyranyl, methyloxymethyl, tert-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 chosen from the group formed by hydrogen and a C 1 -C 11 alkyl, preferably methyl; 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 the group consisting of a C aryl 6 -C 30 , a C aralkyl 7 -C 30 and a C alkyl 2 -C 30 , preferably a C aryl 6 -C 18 .

[0043] According to a further preferred embodiment, the monomer M1 is chosen from the monomers of general formula (Ibis): in which x is an integer ranging from 1 to 18, preferably from 2 to 18.

[0044] According to a preferred embodiment, the copolymer A1 comprises repeating units corresponding to at least one monomer M3 of general formula (X): in which: Z 1 , Z 2 , Z 3 , identical or different, represent groups chosen from a hydrogen atom, a C 1 -C 12 alkyl, a group -OZ', -C(O)-OZ' with Z' a C 1 -C 12 alkyl.

[0045] According to a further preferred embodiment, the monomer M3 is styrene.

[0046] According to a further preferred embodiment, the repeating units corresponding to monomers of formula (X) represent from 2 to 50% by moles relative to the total number of moles of repeating units of which the copolymer A1 is composed.

[0047] According to a preferred embodiment, the main chain of the comb copolymer A1 comprises at least two repeating units corresponding to monomers M2 of formula (II) having different R 3 groups.

[0048] According to a further preferred embodiment, one of the monomers M2 of the copolymer A1 has the general formula (II-A): in which: R 2 is selected from the group formed by -H, -CH 3 and -CH 2 -CH 3 , R" 3 is a C 1 -C 8 alkyl group, and the other monomer M2 of the copolymer A1 has the general formula (II-B): in which: R 2 is chosen from the group formed by -H, -CH 3 and -CH 2 -CH 3 , R‴ 3 is a C 9 -C 30 alkyl group.

[0049] According to a preferred embodiment, at least a portion of the side chains of the comb copolymer A1 are oligomers O1 comprising a polyolefin fragment and the main chain of the comb copolymer A1 comprises at least one repeating unit corresponding to monomers M2 of general formula (II-A): in which: R 2 is selected from the group consisting of -H, -CH 3 and -CH 2 -CH 3 , R" 3 is a C 1 -C 8 alkyl group.

[0050] According to a preferred embodiment, the repeating units corresponding to monomers M2 represent from 10 to 90%, preferably from 30 to 80%, in moles relative to the total number of moles of repeating units of which the copolymer A1 is composed.

[0051] According to a preferred embodiment, the repeating units corresponding to monomers M1 represent from 1 to 50%, preferably from 5 to 30% by mole relative to the total number of moles of the repeating units of which the copolymer A1 is composed.

[0052] According to a preferred embodiment, the copolymer A1 has a degree of branching ranging from 0.1 to 10 mol%. The degree of branching is calculated by taking into consideration only the oligomeric side chains comprising more than 30 carbon atoms.

[0053] Preferably, the copolymer A1 has a degree of branching ranging from 0.5 to 5 mol% when the oligomeric chains are olefins with more than 100 carbon atoms, from 5 to 10 mol% when the oligomeric chains are olefins with 30 to 100 carbon atoms.

[0054] According to a preferred embodiment, the comb copolymer A1 comprises non-oligomeric pendant chains which have an average length ranging from 1 to 10 carbon atoms, preferably from 3 to 8 carbon atoms.

[0055] According to a preferred embodiment, the main chain of the comb copolymer A1 has a number-average degree of polymerization ranging from 40 to 2000, preferably from 40 to 1000.

[0056] According to a preferred embodiment, the oligomeric pendant chains of the comb copolymer A1 have a number-average degree of polymerization ranging from 8 to 1000.

[0057] According to a first embodiment, compound A2 is a compound of formula (III): in which: w 1 and w 2 , identical or different, are integers chosen between 0 and 1; R 4 , R 5 , R 6 and R 7 , identical or different, represent a group chosen from a hydrogen atom, a hydrocarbon group comprising from 1 to 30 carbon atoms, optionally substituted by one or more groups chosen from: a hydroxyl, a -OJ group, -C(O)-OJ with J a hydrocarbon group comprising from 1 to 24 carbon atoms; L is a divalent linking group and chosen from the group formed by a C 6 -C 18 aryl, a C 6 -C 18 aralkyl and a C 2 -C 24 hydrocarbon chain.

[0058] According to a second embodiment, compound A2 is a copolymer comprising at least: ▪ repeating units corresponding to monomers M4 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 linking groups, identical or different, chosen from the group formed by a C 6 -C 18 aryl, a C 7 -C 24 aralkyl and a C 2 -C 24 alkyl; preferably M is a C 6 -C 18 aryl, and R 8 is a C 7 -C 24 aralkyl; X is a function chosen from the group formed by -OC(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 chain comprising from 1 to 15 carbon atoms; R 9 is chosen from the group formed by -H, -CH 3 and -CH 2 -CH 3; R 10 and R 11, identical or different, represent a group chosen from a hydrogen atom, a hydrocarbon group comprising from 1 to 30 carbon atoms, optionally substituted by one or more groups chosen from: a hydroxyl, a group -OJ, -C(O)-OJ with J a hydrocarbon group comprising from 1 to 24 carbon atoms;▪ Repeating units corresponding to M5 monomers of general formula (V): ; in which: R 12 is selected from the group consisting of -H, -CH 3 and -CH 2 -CH 3 , R 13 is selected from the group consisting of a C 6 -C 18 aryl, a C 6 -C 18 aryl substituted by a group R' 13 , -C(O)-OR' 13 ; -OR' 13 , -SR' 13 and -C(O)-N(H)-R' 13 with R' 13 being a C 1 -C 30 alkyl group.

[0059] According to a preferred embodiment, when the compound A2 is a copolymer comprising at least two boronic ester functions, it is a comb copolymer comprising a main chain and side chains, at least part of the side chains of the copolymer A2 being composed of oligomers.

[0060] According to a preferred embodiment, when compound A2 is a copolymer at least one of the following three conditions is met: either in formula (IV): u = 1, R 9 is H and R 8 represents a C 6 -C 18 aryl or a C 7 -C 24 aralkyl and the double bond of the monomer M4 of formula (IV) is directly connected to the aryl group; or in formula (V): R 12 represents H and R 13 is chosen from the group formed by a C 6 -C 18 aryl and a C 6 -C 18 aryl substituted by a group R' 13 with R' 13 represents H or a C 1 -C 25 alkyl group and the double bond of the monomer M5 of formula (V) is directly connected to the aryl group; or the copolymer A2 comprises at least a third monomer M3 of formula (X) in which: Z 1 , Z 2 , Z 3 , identical or different, represent groups chosen from a hydrogen atom, a C 1 -C 12 alkyl, a -OZ', -C(O)-OZ' group with Z' a C 1 -C 12 alkyl.

[0061] Advantageously, when A2 comprises a third monomer M3 of formula (X), this monomer M3 is styrene.

[0062] Advantageously, the boronic ester copolymer A2 has a molar percentage of styrenic monomer(s), advantageously styrene, of formula (IV), (V) and / or (X), in said copolymer ranging from 0.05 to 30 mol%, preferably from 0.1 to 25%.

[0063] According to a preferred embodiment, the content of copolymer A1 ranges from 0.1% to 50% by weight relative to the total weight of the composition.

[0064] According to a preferred embodiment, the content of compound A2 ranges from 0.1% to 50% by weight relative to the total weight of the composition.

[0065] According to a preferred embodiment, the mass ratio between the copolymer A1 and the compound A2 (ratio A1 / A2) ranges from 0.005 to 200, preferably from 0.05 to 20, even more preferably from 0.1 to 10.

[0066] According to a preferred embodiment, the copolymer A1 was obtained by a process comprising at least: a radical polymerization step controlled by reversible chain transfer by addition-fragmentation in the presence of a thiocarbonylthio type transfer agent.

[0067] According to a further preferred embodiment, the copolymer A1 was obtained by a process comprising at least after the polymerization: an aminolysis step of the thiocarbonylthio residue to thiol, followed by a Michael addition to an acrylate to transform the thiol into thioether.

[0068] According to a preferred embodiment, the composition further comprises at least one exogenous compound A4 chosen from polyols.

[0069] According to a preferred embodiment, the molar percentage of exogenous compound A4 relative to the boronic ester functions of the copolymer A2 ranges from 0.025 to 5000%, preferably from 0.1% to 1000%, even more preferably from 0.5% to 500%, even more preferably from 1% to 150%.

[0070] According to another preferred embodiment, the composition further comprises at least one exogenous compound A5 chosen from those corresponding to formula (XI): in which: Q represents a group chosen from a hydrocarbon group comprising from 1 to 30 carbon atoms, optionally substituted by one or more groups chosen from: a hydroxyl, a -OJ group, -C(O)-OJ with J a hydrocarbon group comprising from 1 to 24 carbon atoms, G 4 , G 5 , identical or different, represent groups chosen from a hydrogen atom, a hydrocarbon chain comprising from 1 to 24 carbon atoms, a hydroxyl, a -OJ group, -C(O)-OJ with J a hydrocarbon group comprising from 1 to 24 carbon atoms, g represents 0 or 1.

[0071] According to a preferred embodiment, the lubricating oil is selected from oils of group I, group II, group III, group IV, group V of the API classification and a mixture thereof.

[0072] According to a preferred embodiment, the lubricating composition comprises at least one functional additive chosen from the group formed by antioxidants, detergents, anti-wear additives, extreme pressure additives, viscosity index improving polymers, pour point improvers, anti-foams, anti-corrosion additives, thickeners, dispersants, friction modifiers and mixtures thereof. Detailed description

[0073] The expression "consists essentially of" followed by one or more characteristics means that, in addition to the components or steps explicitly listed, components or steps which do not significantly modify the properties and characteristics of the invention may be included in the process or material of the invention.

[0074] The expression "between X and Y" includes the limits, unless explicitly stated otherwise. This expression therefore means that the interval in question includes the values ​​X, Y and all values ​​from X to Y. > Definitions :

[0075] An oligomer is a macromolecule consisting of a limited number of repeating units. These repeating units may all be identical, or an oligomer may contain different repeating units. Typically, an oligomer contains 2 to 1,000 repeating units. Most often, an oligomer results from the polymerization or copolymerization of a limited number of monomers. An oligomer comprises a main chain and may include side chains, also known as pendant chains.

[0076] The main chain of a polymer or oligomer is a linear chain from which all other chains can be considered as pendants. When several chains can be considered as a main chain, the main chain is designated as the one which leads to the simplest representation of the molecule. The term "main chain" as used herein does not necessarily mean that the chain length of the main chain is greater than that of the side chains.

[0077] A side chain or pendant chain is a substituent of a macromolecular chain. This substituent may be a low molecular weight molecule, an oligomer, or a polymer. Oligomeric pendant chains comprise a chain of at least 30 carbon atoms, preferably at least 50 carbon atoms, and more preferably at least 70 carbon atoms.

[0078] By "copolymer" is meant a linear or branched oligomer or macromolecule having a sequence consisting of several repeating units (or monomeric unit) of which at least two units have a different chemical structure.

[0079] A "monomer unit" or "monomer" means a molecule capable of being converted into an oligomer or macromolecule by combination with itself or with other molecules of the same type. A monomer is the smallest building block whose repetition leads to an oligomer or macromolecule.

[0080] By "comb polymer", also referred to as a branched or branched copolymer, is meant a polymer which has a main chain and at least one side chain or pendant chain attached to the main chain at a point located between the two ends of the main chain, called a branch point or branch point. Unlike linear polymers which comprise non-polymeric side groups or pendant groups, the side chains of comb polymers are oligomers, polymers or copolymers. Preferably, according to the invention, a comb polymer comprises at least two, even better at least three side chains or pendant chains. The degree of branching within the meaning of the invention characterizes the branching by oligomeric side chains having more than 30 carbon atoms.

[0081] A "statistical copolymer" means an oligomer or macromolecule in which the sequential distribution of the monomer units obeys known statistical laws. For example, a copolymer is said to be statistical when it consists of monomer units whose distribution is a Markovian distribution. A schematic statistical polymer (P1) is illustrated in figure 1 The distribution in the polymer chain of the monomer units depends on the reactivity of the polymerizable functions of the monomers and the relative concentration of the monomers.

[0082] A "block copolymer" means an oligomer or macromolecule that comprises one or more blocks or that is made up of blocks. A "block" means a part of a copolymer comprising several identical or different monomer units and which have at least one constitutional or configurational feature that allows it to be distinguished from its adjacent parts. A schematic block copolymer (P3) is illustrated in figure 1 .

[0083] A "gradient copolymer" means a copolymer of two or more structurally different monomer units whose monomer composition changes gradually along the polymer chain, thus passing progressively from one end of the polymer chain rich in one monomer unit, to the other end rich in the other comonomer. A schematic gradient polymer (P2) is illustrated in figure 1 .

[0084] The polydiol copolymers of the invention are random copolymers or gradient copolymers. They may have a gradient distribution of some monomers and a random or quasi-random distribution of other monomers. They are distinguished from block copolymers.

[0085] The term "copolymerization" means a process that converts a mixture of at least two monomer units of different chemical structures into an oligomer or a copolymer.

[0086] Polyolefins are known to those skilled in the art. They can be obtained by polymerizing alkenes and / or alkanedienes consisting of carbon and hydrogen, for example C2-C10 alkenes such as ethylene, propylene, n-butene, isobutene, cyclobutene, cycloheptene, cyclooctene, norbornene, and / or C4-C10 alkadienes such as butadiene, isoprene, cyclooctadiene, norbornadiene. According to the invention, the definition of polyolefins includes: hydrogenated polyolefins, hydrogenated poly(alkanedienes), the hydrogenation being partial or total, copolymers of olefin, polyolefin, hydrogenated polyolefin and hydrogenated polyolefin-co-polyolefin.

[0087] In the remainder of this application, “B” represents a boron atom.

[0088] “C i -C j alkyl” means a saturated, linear or branched hydrocarbon chain comprising from i to j carbon atoms. For example, “C 1 -C 10 alkyl” means a saturated, linear or branched hydrocarbon chain comprising from 1 to 10 carbon atoms.

[0089] By "C x -C y aryl" is meant a functional group that is derived from an aromatic hydrocarbon compound comprising from x to y carbon atoms. This functional group may be monocyclic or polycyclic. For illustration, a C 6 -C 18 aryl may be phenyl, naphthalene, anthracene, phenanthrene and tetracene.

[0090] By “C x -C y alkenyl” is meant a linear or branched hydrocarbon chain comprising at least one unsaturation, preferably a carbon-carbon double bond, and comprising from x to y carbon atoms.

[0091] By "C x -C y aralkyl" is meant an aromatic hydrocarbon compound, preferably monocyclic, substituted by at least one linear or branched alkyl chain and whose total number of carbon atoms in the aromatic ring and its substituents ranges from x to y carbon atoms. By way of illustration, a C 7 -C 18 aralkyl may be chosen from the group formed by benzyl, tolyl and xylyl.

[0092] By “C x -C y aryl group substituted by a group Y” is meant an aromatic hydrocarbon compound, preferably monocyclic, comprising from x to y carbon atoms of which at least one carbon atom of the aromatic cycle is substituted by a group Y.

[0093] By "Hal" or "halogen" is meant a halogen atom selected from the group consisting of chlorine, bromine, fluorine and iodine.

[0094] In the description, when it is indicated that a copolymer "comprises repeating units corresponding to a monomer M i ", this means that the copolymer can result directly from the copolymerization of the monomer M i , and i represents an index identifying the different monomers illustrated below, with other comonomers, but also that the copolymer can have been obtained by copolymerization of monomers other than the monomer M i and have then been subjected to a chemical transformation step, such that the structural units that it comprises are identical to those which would have been obtained by copolymerization of the monomer M i .For example, an acid-functional monomer, such as acrylic acid or methacrylic acid, may first be copolymerized with other monomers to form a copolymer, and then all or part of the acid functions may then be transformed by any reaction, for example by means of an esterification reaction with an alkanol or amidation with an alkylamine. A copolymer comprising repeating units corresponding to an alkyl acrylate or alkyl acrylamide monomer will then be obtained. > Composition of additives according to the invention:

[0095] An object of the present invention is a composition of associative and thermoreversibly exchangeable compounds, this composition resulting from the mixture of at least: a polydiol comb copolymer A1 as described below or in particular capable of being obtained by one of the processes described below; a compound A2 comprising at least two boronic ester functions.

[0096] This additive composition makes it possible to control and modulate the rheological behavior of a medium in which it is added. The medium can be a hydrophobic medium, in particular apolar, such as a solvent, a mineral oil, a natural oil, a synthetic oil. ∘ Polydiol A1 comb copolymers

[0097] The polydiol comb copolymer A1 comprises a main chain to which side chains are attached, at least a portion of the side chains of the copolymer A1 being composed of oligomers.

[0098] The side chains of the comb copolymer A1 according to the invention are distinguished from the side chains of the polyol copolymers of the prior art used in a mixture with boronic esters in that at least part of the side chains is composed of oligomers.

[0099] By "side chain composed of oligomers" is meant that at least part of the side chain is an oligomer of one or more monomers. It is not excluded that this side chain includes other functionalities such as for example a function or a succession of functions linking the side chain to the main chain. • Side chains of A1 copolymers

[0100] The side chains of the copolymers A1 composed of oligomers have a degree of polymerization which is not zero, unlike the side chains of the copolymers of the same type which are known from the prior art.

[0101] Preferably, the side chains composed of oligomers represent from 3 to 95% by mass relative to the total mass of the copolymer A1, preferably from 15 to 95%, better still from 20 to 95%.

[0102] At least part of the side chains of copolymer A1 is composed of oligomers comprising more than 30 carbon atoms, preferably at least 50 carbon atoms, even better at least 70 carbon atoms.

[0103] Preferably, the side chains composed of oligomers comprising more than 30 carbon atoms represent from 3 to 95% by mass relative to the total mass of the copolymer A1, preferably from 15 to 95%, better still from 20 to 95%.

[0104] At least a portion of the side chains of the copolymers A1 composed of oligomers have a degree of polymerization ranging from 5 to 1000, preferably from 5 to 500, even better from 5 to 200.

[0105] Even more preferably, the side chains composed of oligomers with a degree of polymerization ranging from 5 to 1000 represent from 3 to 95% by mass relative to the total mass of the copolymer A1, preferably from 15 to 95%, better still from 20 to 95%.

[0106] The oligomeric side chains of the A1 copolymers can all be of the same nature or they can be of different nature.

[0107] A1 copolymers may include oligomeric side chains and side chains that are not oligomers.

[0108] Preferably, the side chains of the copolymers A1 which are not oligomeric compounds represent from 5 to 97% by mass relative to the total mass of the copolymer A1, preferably from 5 to 85%, better still from 5 to 80%, more preferably still from 5 to 75% by mass relative to the total mass of the copolymer A1.

[0109] According to a first variant, at least a portion of the side chains of the copolymer A1 is composed of oligomers O1 comprising a polyolefin fragment. The polyolefin fragment can be obtained from a polyolefin macromonomer or from a functionalized monomer onto which a polyolefin function is grafted.

[0110] Preferably, the side chains comprising a polyolefin fragment represent from 8 to 50%, preferably from 10 to 40% by mass relative to the total mass of the copolymer A1.

[0111] For example, the side chains comprising a polyolefin moiety may consist of repeating units corresponding to a monomer M6 of general formula (IX), derived from a polyolefin.

[0112] According to another variant, a part of the side chains of the copolymer A1 is composed of oligomers O2 comprising repeating units corresponding to monomers chosen from monomers M2 of general formula (II).

[0113] For example, according to this variant, part of the side chains of copolymer A1 is composed of oligomers O2 comprising repeating units corresponding to monomers chosen from: monomers M1 of general formula (I), monomers M2 of general formula (II).

[0114] The copolymer A1 may comprise both side chains of oligomer type O1 comprising a polyolefin fragment and of oligomer type O2 comprising repeating units corresponding to monomers chosen from monomers M2 of general formula (II). • The main chain of A1 copolymers

[0115] The main chain of the comb copolymer A1 preferably comprises repeating units corresponding to monomers M1 of general formula (I).

[0116] The main chain of the comb copolymer A1 may comprise repeating units corresponding to monomers M2 of general formula (II).

[0117] Preferably, the main chain of the comb copolymer A1 comprises repeating units corresponding to at least one monomer M3, of general formula (X) defined above. According to this variant, the other monomers which enter into the composition of the polydiol comb copolymer A1 must be compatible with copolymerization with monomers M3.

[0118] Copolymer A1 can be a random copolymer or a gradient copolymer.

[0119] Advantageously, the polydiol comb copolymer A1 results, directly or indirectly, from the (co)polymerization of at least one diol monomer M1, which is introduced either into the main chain, or into the side chains, or both into the main chain and into the side chains of the copolymer A1.

[0120] By "results directly or indirectly" is meant that the process for preparing the copolymer may comprise one or more separate steps of the copolymerization, such as a deprotection step. In particular, the copolymerization may optionally be followed by a step of deprotection of the diol functions.

[0121] Throughout the description, the expressions: “the polydiol copolymer A1 results, directly or indirectly, from the copolymerization” and “the polydiol copolymer A1 results from the copolymerization” are used interchangeably and equivalently. • Distribution of monomers in the main chain and in the side chains

[0122] Monomers M1, M2 and M3 can be present in the main chain and / or in the side chains. In the side chains, they are present as oligomers. Other monomers may also be present in the main chain and / or in the side chains.

[0123] M6 monomers can be used in the copolymerization of the main chain and provide oligomeric side chains.

[0124] When monomers M1, M2 and / or M3 are integrated into the main chain of a copolymer A1 according to the invention, the side chains of the monomers M1, M2 and M3 form non-oligomeric side chains of the copolymer A1.

[0125] The comb copolymer A1 comprises non-oligomeric side chains which preferably have an average length ranging from 1 to 10 carbon atoms, even more preferably from 3 to 8 carbon atoms.

[0126] When the comb copolymer A1 comprises oligomeric side chains consisting of monomer M1 or monomer M2, these monomers preferably have an average length ranging from 1 to 10 carbon atoms.

[0127] By "average length" is meant the average length of the alkyl fragments of the side chains of the monomers M1 of formula (I) and M2 of formula (II) forming part of the copolymer A1. The side chains derived from the styrene monomer(s) are not taken into account in the calculation of the average lengths of the side chains of the comb copolymers A1. A person skilled in the art knows how to obtain this average length by appropriately selecting the types and ratio of monomers constituting the polydiol copolymer.

[0128] Unless specifically indicated, the preferences expressed below for the choice of monomers M1, M2 and M3 are valid both when the monomers M1, M2 and M3 are present as repeating units in the main chain and when they are present in the pendant chains. • Monomer MI

[0129] The first monomer M1 of the comb copolymer (A1) of the invention has the general formula (I): in which: R 1 is chosen from the group formed by -H, -CH 3 and -CH 2 -CH 3 , preferably -H and -CH 3 ; Y represents a divalent linking group chosen from C 1 -C 20 alkyl chains, optionally comprising one or more ether bridges -O-; preferably Y represents a group chosen from: a chain -(CH 2 ) x - or -(CH 2 ) x' -O-(CH 2 ) x" - with x being an integer ranging from 1 to 18, preferably ranging from 2 to 18; more preferably from 3 to 8; even more preferably x is equal to 4; x', x'' are integers ranging from 1 to 17, x'+x'' is an integer ranging from 2 to 18; more preferably from 3 to 8; advantageously, x' is an integer ranging from 1 to 4, x" = 1; even more preferably x' = 2, x'' = 1; y is an integer equal to 0 or 1; preferably y is equal to 0;X 1 and X 2 , identical or different, are chosen from the group formed by hydrogen, tetrahydropyranyl, methyloxymethyl, tert-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 chosen from the group formed by hydrogen and a C 1 -C 11 alkyl group; 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 chosen from the group formed by a C 6 -C 30 aryl, a C 7 -C 30 aralkyl and a C 2 -C 30 alkyl, preferably a C 6 -C 18 aryl, more preferably phenyl.

[0130] Preferably, when R' 2 and R'' 2 are a C 1 -C 11 alkyl group; the hydrocarbon chain is a straight chain. Preferably, the C 1 -C 11 alkyl group is selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decycle and n-undecyl. More preferably, the C 1 -C 11 alkyl group is methyl.

[0131] Preferably, when R‴ 2 is a C 2 -C 30 alkyl group, the hydrocarbon chain is a straight chain.

[0132] More preferably, the monomer M1 corresponds to the general formula (Ibis): Where x is an integer ranging from 1 to 18, preferably from 2 to 18; more preferably from 3 to 8; even more preferably x is equal to 4.

[0133] Among the monomers of formula (I), the monomers corresponding to the formula (IA) are among the preferred: in which: R 1 is selected from the group formed by -H, -CH 3 and -CH 2 -CH 3 , preferably -H and -CH 3 ; Y represents a divalent linking group selected from: a chain - (CH 2 ) x - or - (CH 2 ) x' - O- (CH 2 ) x" - with x being an integer ranging from 1 to 18, preferably ranging from 2 to 18; more preferably from 3 to 8; even more preferably x is equal to 4; x', x'' being integers ranging from 1 to 17, x'+x'' being an integer ranging from 2 to 18; more preferably from 3 to 8; advantageously, x' is an integer ranging from 1 to 4, x" = 1; even more preferably x' = 2, x" = 1; y is an integer equal to 0 or 1; preferably y is equal to 0. Among the monomers of formula (IA), those corresponding to the formula (Ibis-A) are among the preferred: in which R 1 , x, y have the same definition and preferences as in formula (IA).

[0134] Among the monomers of formula (I), the monomers corresponding to formula (IB) are among the preferred: in which: R 1 is selected from the group formed by -H, -CH 3 and -CH 2 -CH 3 , preferably -H and -CH 3 ; Y represents a divalent linking group selected from: a chain - (CH 2 ) x - or - (CH 2 ) x' - O- (CH 2 ) x" - with x being an integer ranging from 1 to 18, preferably ranging from 2 to 18; more preferably from 3 to 8; even more preferably x is equal to 4; x', x'' are integers ranging from 1 to 17, x'+x'' is an integer ranging from 2 to 18; more preferably from 3 to 8; advantageously, x' is an integer ranging from 1 to 4, x" = 1; even more preferably x' = 2, x'' = 1; y is an integer equal to 0 or 1; preferably y is equal to 0; Y 1 and Y 2 , identical or different, are chosen from the group formed by tetrahydropyranyl, methyloxymethyl, tert-butyl, benzyl, trimethylsilyl and t-butyl dimethylsilyl; or else Y 1 and Y 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 chosen from the group formed by hydrogen and a C 1 -C 11 alkyl group; or Y 1 and Y 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 chosen from the group formed by a C 6 -C 30 aryl, a C 7 -C 30 aralkyl and a C 2 -C 30 alkyl, preferably a C 6 -C 18 aryl, more preferably phenyl.

[0135] Preferably, when R' 2 and R'' 2 is a C 1 -C 11 alkyl group; the hydrocarbon chain is a straight chain. Preferably, the C 1 -C 11 alkyl group is selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decycle and n-undecyl. More preferably, the C 1 -C 11 alkyl group is methyl.

[0136] Preferably, when R‴ 2 is a C 2 -C 30 alkyl group, the hydrocarbon chain is a straight chain.

[0137] Among the monomers of formula (IB), those corresponding to the formula (Ibis-B) are among the preferred: in which R 1 , x, y, Y 1 , Y 2 , have the same definition and preferences as in formula (IB).

[0138] Examples of preferred diol monomers of formula (I) are illustrated below: CAS 45755-07-1 CAS 86218-23-7 CAS 60503-49-3 CAS 60503-48-2 CAS 7098-80-8 CAS 5919-74-4

[0139] The synthesis of the polydiol comb copolymer (A1) may involve the copolymerization of monomers (IB) in protected form with other comonomers, followed by deprotection of the diol functions of the monomers (IB). • Obtaining monomer M1

[0140] The monomer M1 of general formula (I) is obtained according to the methods described in WO2015 / 110642, WO2015 / 110643 and WO2016113229.

[0141] Examples of synthesis of M1 monomers are illustrated in the experimental part of applications WO2015 / 110642, WO2015 / 110643 and WO2016113229. • Monomer M2

[0142] The second monomer of the comb copolymer A1 of the invention has the general formula (II): in which: R 2 is selected from the group consisting of -H, -CH 3 and -CH 2 -CH 3 , preferably -H and -CH 3 ; R 3 is selected from the group consisting of a C 6 -C 18 aryl group, a C 6 -C 18 aryl substituted by an R' 3 group, -C(O)-OR' 3 -OR' 3 , -SR' 3 and -C(O)-N(H)-R' 3 , with R' 3 being a C 1 -C 30 alkyl group.

[0143] Preferably, R' 3 is a C 1 -C 30 alkyl group whose hydrocarbon chain is linear.

[0144] Among the monomers of formula (II), the monomers corresponding to the formula (II-A) are among the preferred: in which: R 2 is selected from the group consisting of -H, -CH 3 and -CH 2 -CH 3 , preferably -H and -CH 3 ; R" 3 is a C 1 -C 8 alkyl group, preferably R" 3 is linear.

[0145] Preferably, the units corresponding to monomers (IIA) are present in the main chain of copolymer A1.

[0146] Among the monomers of formula (II), the monomers corresponding to the formula (II-B) are also among the preferred: in which: R 2 is selected from the group consisting of -H, -CH 3 and -CH 2 -CH 3 , preferably -H and -CH 3 ; R‴ 3 is a C 9 -C 30 alkyl group, preferably, R‴ 3 is linear.

[0147] Preferably, the units corresponding to monomers (IIB) are present in the oligomeric pendant chains of copolymer A1. • Obtaining monomer M2

[0148] The monomers of formula (II), (II-A) and (II-B) are well known to those skilled in the art. They are marketed by Sigma-Aldrich ®< and TCI ®<. • Monomer M3

[0149] The third monomer of the comb copolymer A1 of the invention has the general formula (X): in which: Z 1 , Z 2 , Z 3 , identical or different, represent groups chosen from a hydrogen atom, a C 1 -C 12 alkyl, a group -OZ', - C(O)-OZ' with Z' a C 1 -C 12 alkyl.

[0150] By “C 1 -C 12 alkyl group” is meant a saturated, linear or branched hydrocarbon chain comprising from 1 to 12 carbon atoms. Preferably, the hydrocarbon chain is linear. Preferably, the hydrocarbon chain comprises from 1 to 6 carbon atoms.

[0151] Advantageously, Z 1 , Z 2 , Z 3 , identical or different, represent groups chosen from a hydrogen atom, a C 1 -C 6 alkyl, a group -OZ', -C(O)-OZ' with Z' a C 1 -C 6 alkyl.

[0152] More preferably, Z 1 , Z 2 , Z 2 , identical or different, represent groups chosen from a hydrogen atom, a C 1 -C 4 alkyl, a group -OZ', -C(O)-OZ' with Z' a C 1 -C 4 alkyl.

[0153] Among the preferred M3 monomers, mention may be made of: styrene, para tert-butyl styrene, para methoxy styrene, para acetoxy styrene, 2,4,6 trimethylstyrene,

[0154] According to a preferred embodiment M3 is styrene. • Obtaining monomer M3

[0155] Certain monomers of formula (X), such as styrene, para-tert-butyl styrene, para-methoxystyrene, para-acetoxystyrene, 2,4,6-trimethylstyrene are well known to those skilled in the art. They are marketed in particular by Sigma-Aldrich ®< . Other monomers can be prepared from these commercial monomers by synthetic methods well known to those skilled in the art. • Monomer M6

[0156] The monomer M6 has the general formula (IX): in which Q 1 is selected from the group consisting of -H, -CH 3 , and -CH 2 -CH 3 ; Q 2 is selected from a group -Q', -O-Q', -C(O)-O-Q', -O- C(O)-Q', - S-Q', -S-(CH 2 ) 2 -C(O)-O-Q', -N(H)-C(O)- Q' and -C(O)-N(H)-Q' with Q' is a polyolefin, n represents an integer selected from 0 and 1, A represents a divalent group selected from: -A 1 -, -O-(-A 2 -O-)n'-A 1 -, - C(O)-O- (-A 2 -O-)n'-A 1 -, -OC(O)-(-A 2 -O-)n'-A 1 -, -S-(-A 2 -O-)n'-A 1 -, -N(H)-C(O)-(-A 2 -O-)n'- A 1 - and -C(O)-N(H)-( -A 2 -O-)n'-A 1 - with: A 1 is a divalent group chosen from C 1 -C 30 alkyl, C 6 -C 30 aryl, C 6 -C 30 aralkyl, A 2 is a divalent group chosen from C 2 -C 4 alkyl, n' is an integer, n' represents 0 or 1.

[0157] For example A 2 can be chosen from: -CH 2 -CH 2 -, -CH 2 -CH 2 -CH 2 -, -CH 2 -C(CH 3 )H-.

[0158] Preferably A 2 is linear, even more preferably A 2 represents - CH 2 -CH 2 -.

[0159] Preferably, in formula (IX) Q 1 represents -H.

[0160] Preferably, in formula (IX), Q 2 is chosen from a group -Q', - S-(CH 2 ) 2 -C(O)-OQ' or -C(O)-O-Q', with Q' a polyolefin.

[0161] According to a first variant, n=0 and Q 1 = CH 3 .

[0162] According to a second, preferred variant, n=1, n'=0, Q 1 = H and A 1 is a divalent group chosen from a C 1 -C 12 alkyl, a C 6 -C 12 aryl, a C 6 -C 12 aralkyl.

[0163] Preferably according to this second variant, n=1, Q1 = H and A = paraphenyl.

[0164] Polyolefin-based macromonomers such as those of formula (IX) are known. These repeating units comprise at least one Q' group derived from polyolefins.

[0165] Preferably, in formula (IX), Q' represents a polyolefin or a hydrogenated polyolefin derived from alkene or alkanedienes, such as ethylene, propylene, n-butene, iso-butene, butadiene, isoprene, cyclobutene, cycloheptene, cyclooctene.

[0166] The repeating units M6 derived from polyolefin-based macromonomers preferably comprise at least 90% by weight and more preferably at least 92.5% by weight and more preferably at least 95% by weight of groups derived from alkenes and / or alkadienes, relative to the weight of the repeating units M6. The polyolefin groups Q' may in particular also be present in hydrogenated form.

[0167] Preferably Q' represents a polyolefin chosen from hydrogenated polybutadienes with a number-average molecular weight of 400 to 50,000 g / mol, better still 500 to 50,000 g / mol, more preferably 1000 to 10,000 g / mol, in particular 1500 to 5000 g / mol and even more preferably 500 to 5000 g / mol, or even 700 to 3000 g / mol.

[0168] Preferably Q' represents a polyolefin comprising from 30 to 500 carbon atoms, preferably from 50 to 400 carbon atoms, or from 70 to 200 carbon atoms. • Obtaining the repeating units corresponding to the monomer M6

[0169] The repeating units corresponding to the monomer M6 can be obtained by any means known to those skilled in the art.

[0170] The monomers M6 with Q 1 representing H, Q 2 representing -C(O)-O-Q', Q' being a polyolefin, can be obtained by reaction of acrylic acid with an alcohol Q'OH, acryloyl chloride with an alcohol Q'OH or acrylic anhydride with an alcohol Q'OH.

[0171] The monomers M6 with Q 1 representing CH 3 , Q 2 representing -C(O)-O-Q', Q' being a polyolefin, can be obtained by reaction of methacrylic anhydride with an alcohol Q'OH or of methacrylic acid with an alcohol Q'OH.

[0172] Alternatively, a repeating unit corresponding to the monomer M6 can be introduced with Q 1 representing H, respectively CH 3 , Q 2 representing -C(O)-O-Q', Q' being a polyolefin or a hydrogenated polyolefin, by functionalizing the backbone after polymerization, for example by proceeding according to the following sequence: copolymerization of acrylic acid, respectively methacrylic acid, with other monomers such as, for example, the monomers M1 of formula (I) and optionally the monomers M2 of formula (II) and / or the monomers M3 of formula (X), to form the backbone of the comb copolymer A1, esterification of at least part of the acid functions of the (meth)acrylic acid monomer by reaction with an alcohol Q'OH.

[0173] The polyolefinic alcohols that are used can be prepared in particular by the following methods: synthesis of a hydroxyl-terminated polybutadiene as taught by US5159123 then hydrogenation, for example by the method described in US7148292. Among the commercially available polyolefinic alcohols that can be used, mention may be made of Krasol HLBH 5000M polybutadiene marketed by the company Cray Valley.

[0174] For the other variants of Q 2 , the person skilled in the art similarly uses conventional reactions for functionalizing a polymerizable group before or after the polymerization of the backbone chain, or main chain, of the copolymer A1, in particular by esterification reactions, amidation reactions, by thiol-ene coupling reactions, by Michael addition between a thiol function and an acrylate, acrylamide or maleimide function, etc. • Pendant chains based on M1 oligomers / M2 / M3 :

[0175] According to a first embodiment, the copolymer A1 comprises side chains consisting of oligomers comprising repeating units which correspond to monomers chosen from monomers M2 of general formula (II).

[0176] Preferably, according to this variant, the copolymer A1 comprises side chains consisting of oligomers obtained directly or indirectly from monomers chosen from monomers M2 of general formula (II).

[0177] According to a second embodiment, the copolymer A1 comprises side chains consisting of oligomers comprising repeating units which correspond to monomers chosen from: monomers M1 of general formula (I), monomers M2 of general formula (II).

[0178] Preferably, according to this variant, the copolymer A1 comprises side chains consisting of oligomers obtained directly or indirectly from monomers chosen from: monomers M1 of general formula (I), monomers M2 of general formula (II).

[0179] According to a preferred embodiment, the copolymer A1 comprises side chains consisting of oligomers comprising repeating units which correspond to monomers chosen from: monomers M1 of general formula (I), monomers M2 of general formula (II), monomers M3 of general formula (X).

[0180] Preferably, according to this variant, the copolymer A1 comprises side chains consisting of oligomers obtained directly or indirectly from monomers chosen from: monomers M1 of general formula (I), monomers M2 of general formula (II), monomers M3 of general formula (X). • Obtaining pendant chains based on M1 oligomers / M2 / M3 :

[0181] Oligomeric pendant chains can be obtained directly by copolymerization: of monomers entering into the composition of the main chain, with at least one oligomer comprising a polymerizable function and repeating units corresponding to monomers M2 of general formula (II), and optionally monomers M1 of general formula (I) and / or monomers M3 of general formula (X).

[0182] According to a preferred embodiment, the pendant chains are obtained by copolymerization of monomers entering into the composition of the main chain with at least one so-called “derivation” monomer, followed by grafting of the oligomer(s) onto the derivation function.

[0183] A derivatization monomer is a monomer comprising both a polymerizable function, for example a vinyl or acrylic double bond, and at least one reactive function allowing: the grafting of an already oligomerized pendant chain, or the initiation of a polymerization reaction.

[0184] Preferably, the derivatization monomer is chosen from radical polymerization initiators and transfer agents. The reactive function for initiating the polymerization of a pendant chain may, for example, consist of a brominated function, as described in detail in the experimental part. Other reactive functions well known to those skilled in the art, for example a RAFT agent, a radical polymerization agent in the presence of nitroxides (NMP), a thiol, a diazo, a peroxide may also be used.

[0185] Preferably, the derivatization monomer M7 corresponds to the following formula (XII): in which G 1 represents a group chosen from: -H, -CH 3 , -CH 2 -CH 3 ; M represents a hydrocarbon group comprising from 1 to 40 carbon atoms, optionally one or more functions chosen from -O-, -OC(O)-, -OC(O)-O-, -N(H)-, -N=, -N(H)-C(O)-, -N(H)-C(O)-N(H)-, -S-, -SC(O)-, -SC(S)-O- ; G 2 represents a group chosen from: Cl, Br, I, -C(O)-OH, -G 3 , -C(O)-OG 3 , with G 3 a C 1 -C 12 alkyl group.

[0186] Examples of derivatization monomers include: acrylic acid, methacrylic acid, brominated and xanthate monomers: • Other monomers

[0187] In addition to the repeating units detailed above corresponding to the monomers M1, M2, M3 and M6, the comb polymers A1 of the invention may comprise in the main chain as in the pendant chains, other repeating units derived from other comonomers, their proportion being at most 20% by weight, preferably at most 10% by weight and more preferably at most 5% by weight, based on the total weight of the repeating units of which the copolymer A1 is composed. • Structuring of polydiol comb copolymers A1

[0188] A1 comb polydiol copolymers comprise a main chain, or backbone chain, and at least one side chain or pendant chain.

[0189] Preferably, the polydiol comb copolymers A1 comprise more than two oligomeric side chains or pendant chains.

[0190] Preferably, the main chain comprises at least repeating units corresponding to the monomers M2 of formula (II).

[0191] Preferably, the main chain further comprises at least repeating units corresponding to the monomers M3 of formula (X).

[0192] The main chain advantageously comprises repeating units corresponding to the monomers M1 of formula (I).

[0193] Pendant chains can be chosen in particular from the group consisting of: o The groups Q 2 as defined above in formula (IX) and which are chosen from -Q', -O-Q', -C(O)-O-Q', -O- C(O)-Q', -S-Q', -S-(CH 2 ) 2 -C(O)-O-Q', -N(H)-C(O)- Q' and -C(O)-N(H)-Q' with Q' being a polyolefin.

[0194] The Q 2 groups can optionally be attached to the main chain through a group A chosen from: -A 1 , -O-(A 2 -O)n'-A 1 , -C(O)-O- (A 2 -O)n'-A 1 , -O- C(O)-(A 2 -O)n'-A 1 , -S-(A 2 -O)n'-A 1 , - N(H)-C(O)-(A 2 -O)n'-A 1 and - C(O)-N(H)-(A 2 -O)n'-A 1 with: A 1 is C 1 -C 30 alkyl, C 6 -C 30 aryl, C 6 -C 30 aralkyl, A 2 is C 2 -C 4 alkyl, n' is an integer, n' represents 0 or 1, o Oligomers composed of repeating units corresponding to monomers M2 and optionally monomers M1 and / or M3.

[0195] Thus, repeating units corresponding to M1 monomers and to M2 and M3 monomers can be found on the main chain and / or on the pendant chains.

[0196] It has been represented on the Figures 6A, 6B and 6C different possible distributions of the functionalities of these copolymers.

[0197] In these figures, the diol functional groups (such as those carried by the monomers M1 of formula (I) are designated “F”

[0198] On the Figure 6A, the main chain (P) contains diol functions, while the side chains (L) do not. For example, this figure may correspond to a copolymer based on monomers M1, M2, and possibly M3 and olefinic macromonomers M6.

[0199] On the Figure 6B , the main chain (P) does not contain diol functions, while some side chains (Lb) do, but not the side chains (La). For example, this figure may correspond to a copolymer based on monomers M2 and M3 and olefinic macromonomers M6 (La), side chains (Lb) which are oligomers of M1 and M2 and possibly M3 having been grafted onto the main chain.

[0200] On the Figure 6C, the main chain (P) and certain side chains (Lb) contain diol functions. For example, this figure may correspond to a copolymer based on monomers M1 and M2, and possibly M3 and olefinic macromonomers M6, which forms the side chains (La), side chains which are oligomers of M1 and M2 having been grafted onto the main chain to form the side chains (Lb). • Preferred polydiol copolymers

[0201] In one embodiment, a preferred comb copolymer comprises at least: repeating units corresponding to a first monomer M1 of general formula (I) as described above; repeating units corresponding to a second monomer M2 of formula (II) as described above, in which R 2 is -CH 3 and R 3 is a -C(O)-OR' 3 group with -R' 3 representing H or a C 1 -C 30 alkyl; repeating units corresponding to a third monomer M3 of general formula (X) as described above; in particular styrene.

[0202] In another embodiment, a preferred comb copolymer comprises at least: repeating units corresponding to a first monomer M1 of general formula (I) as described above; repeating units corresponding to a second monomer M2 of formula (II-A) as described above, in which R 2 is -CH 3 and R 3 is a group - C(O)-OR' 3 with -R' 3 representing H or a C 1 -C 8 alkyl; repeating units corresponding to a third monomer M3 of general formula (X) as described above; in particular styrene, oligomeric side chains O1 comprising at least one polyolefin fragment, in particular side chains corresponding to a monomer M6 of general formula (IX), and more preferably Q 2 is chosen from a group - Q', -S-(CH 2 ) 2 -C(O)-OQ' or -C(O)-O-Q', with Q' a polyolefin.

[0203] In another embodiment, a preferred copolymer A1 comprises at least: repeating units corresponding to a first monomer M1 of general formula (I) as described above; repeating units corresponding to a second monomer M2 of formula (II-A) as described above; repeating units corresponding to a third monomer M2 of formula (II-B) as described above, distinct from the first monomer of formula (II-A); and repeating units corresponding to a fourth monomer M3 of general formula (X) as described above, in particular styrene.

[0204] According to this embodiment, a preferred copolymer A1 comprises repeating units corresponding at least to: a first monomer M1 of general formula (I) as described above; a second monomer M2 of formula (II-A) in which R 2 is -CH 3 and R" 3 is a C 1 -C 8 alkyl group, preferably a linear C 1 -C 8 alkyl; a third monomer M2 of formula (II-B), in which R 2 is -CH 3 and R‴ 3 is a C 9 -C 30 alkyl group, preferably a linear C 9 -C 30 alkyl, even better a linear C 12 -C 24 alkyl; and a fourth monomer M3 of general formula (X) as described above, in particular styrene.

[0205] According to this embodiment, a preferred copolymer A1 results from the copolymerization of at least: a first monomer M1 of general formula (I) as described previously; a second monomer M2 which is n-butyl methacrylate; a third monomer M2 chosen from the group formed by palmityl methacrylate, stearyl methacrylate, arachidyl methacrylate and behenyl methacrylate, optionally, a fourth monomer M3 of general formula (X) as described previously, in particular styrene.

[0206] In one embodiment, a preferred comb copolymer comprises at least: repeating units corresponding to a first monomer M1 of general formula (I) as described above; repeating units corresponding to a second monomer M2 of formula (II) as described above, in which R 2 is -CH 3 and R 3 is a group -C(O)-OR' 3 with -R' 3 representing H or a C 1 -C 30 alkyl; repeating units corresponding to a third monomer M6 of formula (IX) as described above, advantageously a monomer M6 of formula (IX) in which Q 1 represents H, n=0, Q 2 is -CO-OQ' and Q' represents an olefin.

[0207] Preferably, the oligomeric side chains represent 20 to 95% by mass relative to the total mass of the copolymer A1.

[0208] According to a first preferred variant, the oligomeric side chains O1 comprising a polyolefin fragment represent 20 to 70% by mass relative to the total mass of the copolymer A1.

[0209] According to a second preferred variant, the oligomeric side chains O2, comprising at least repeating units corresponding to a monomer M2 of general formula (II) and optionally repeating units corresponding to a monomer M1 of general formula (I) and / or repeating units corresponding to a monomer M3 of general formula (X), represent 30 to 95% by mass relative to the total mass of the copolymer A1.

[0210] Preferably, the non-oligomeric side chains represent 5 to 80% by mass relative to the total mass of the copolymer A1.

[0211] Preferably, the repeating units of formula (X) represent from 2 to 50 mol% relative to the total number of moles of the monomers of which the copolymer A1 is composed.

[0212] Preferably, the repeating units corresponding to monomers M2 represent from 10 to 90%, preferably from 30 to 80%, in moles relative to the total number of moles of the monomers of which the copolymer A1 is composed.

[0213] Preferably, the repeating units corresponding to monomers M1 represent from 1 to 50%, preferably from 5 to 30% by moles relative to the total number of moles of the monomers of which the copolymer A1 is composed.

[0214] When calculating the mole % of a repeating unit and / or monomer (such as M1, M2 or M3) relative to the total number of moles of monomers of which copolymer A1 is composed and the latter comprises one or more side chains comprising a polyolefin-type fragment, the polyolefin fragment is included by counting it as a single monomer (M6). • Process for obtaining polydiol copolymers A1

[0215] A person skilled in the art is able to synthesize polydiol comb copolymers A1 using his general knowledge.

[0216] The copolymerization can be initiated in bulk or in solution in an organic solvent by free radical generating compounds. For example, the copolymers of the invention are obtained by known radical copolymerization processes, in particular controlled processes such as the method called Reversible Addition-Fragmentation Chain Transfer (RAFT) and the method called Atom Transfer Radical Polymerization (ARTP). Conventional radical polymerization and telomerization can also be employed to prepare the copolymers of the invention (Moad, G.; Solomon, DH, The Chemistry of Radical Polymerization. 2nd ed.; Elsevier Ltd: 2006; p 639; Matyaszewski, K.; Davis, TP Handbook of Radical Polymerization; Wiley-Interscience: Hoboken, 2002; p 936).

[0217] According to a preferred embodiment, the copolymerization is carried out by conventional radical synthesis, without RAFT chain transfer agent.

[0218] According to a preferred embodiment, the copolymerization is carried out by radical synthesis in the presence of a chain transfer agent of thiol or halogenated derivative type.

[0219] The polydiol comb copolymer A1 is prepared according to a process which comprises at least one polymerization step (a) in which the following are brought into contact: i) monomers chosen from monomers M1 of general formula (I), M2 of general formula (II), M3 of general formula (X), M7 of general formula (XII), M6 of general formula (IX), as described previously; ii) at least one source of free radicals.

[0220] In one embodiment, the method may further comprise iii) at least one chain transfer agent.

[0221] By "a source of free radicals" is meant a chemical compound making it possible to generate a chemical species having one or more unpaired electrons on its external layer. A person skilled in the art can use any known source of free radicals suitable for polymerization processes, in particular controlled radical polymerization. Among the sources of free radicals, preferred, by way of illustration, are benzoyl peroxide, tert-butyl peroxide, diazo compounds such as azobisisobutyronitrile, peroxygenated compounds such as persulfates or hydrogen peroxide, redox systems such as the oxidation of Fe 2+< , persulfate / sodium-metabisulfite mixtures, or ascorbic acid / hydrogen peroxide or compounds that can be cleaved photochemically or by ionizing radiation, for example ultraviolet rays or by beta or gamma radiation.

[0222] By "chain transfer agent" is meant a compound whose purpose is to ensure homogeneous growth of macromolecular chains by reversible transfer reactions between growing species, i.e. polymer chains terminated by a carbon radical, and dormant species, i.e. polymer chains terminated by a transfer agent. This reversible transfer process makes it possible to control the molecular masses of copolymers thus prepared. Preferably in the process of the invention, the chain transfer agent comprises a thiocarbonylthio group -SC(=S)-. Illustrative examples of chain transfer agents include dithioesters, trithiocarbonates, xanthates and dithiocarbamates. A preferred transfer agent is cumyl dithiobenzoate or 2-cyano-2-propyl benzodithioate.

[0223] A "chain transfer agent" also refers to a compound whose purpose is to limit the growth of macromolecular chains being formed by adding monomeric molecules and to initiate new chains, thereby limiting or even controlling the final molecular masses. Such a type of transfer agent is used in telomerization. A preferred transfer agent is cysteamine.

[0224] In one embodiment, the process for preparing a polydiol comb copolymer comprises at least one polymerization step (a) as defined above, in which the monomers M1 and M2 are chosen with X 1 and X 2 representing hydrogen.

[0225] In one embodiment, the process for preparing a polydiol comb copolymer comprises at least one polymerization step (a) as defined above with at least one derivatization monomer M7 of general formula (XII), this polymerization step being followed by: (b) optionally a functionalization of the derivation monomer M7 (c) at least one oligomerization step from the derivation monomer M7 (or from the function derived from M7) or (d) at least one step of grafting an oligomer from the derivation monomer M7 (or from the function derived from M7).

[0226] According to one embodiment (when a radical polymerization with RAFT chain transfer agent has been carried out), after the direct synthesis of the polymer containing the diol functions, the method comprises a step of eliminating the RAFT chain end by aminolysis then Michael addition.

[0227] The preferences and definitions described for general formulae (I), (Ibis), (IA), (IB), (Ibis-A), (Ibis-B), (II-A), (II-B), (IX), (X) and (XII) also apply to the methods described above.

[0228] For the introduction of side chains into polydiol copolymers A1, those skilled in the art can use different synthesis schemes.

[0229] On the figure 7 a grafting synthesis is represented: In step E1, monomers M1, M2 and possibly M3 are copolymerized with derivation comonomers M7 to form a main chain (P): The monomers M1 form repeating units comprising a diol functionality represented by the letter F.

[0230] M7 monomers form repeating units comprising a branching functionality represented by the letter F' (several different F' functions may be present).

[0231] In step E2, the main chain (P) is grafted using part of the F' functions by side chains (La) such as polyolefin chains.

[0232] In step E3, the main chain (P) is grafted using the rest of the F' functions by side chains (Lb) such as, for example, oligomeric chains resulting from the copolymerization of monomers M1 and M2 and possibly M3, these side chains carrying diol functions denoted F belonging to the monomers M1.

[0233] On the figure 8is represented a synthesis by a process comprising both copolymerization with macromonomers and grafting of oligomers, these two techniques allowing the incorporation of side chains: In step E1, various monomers are reacted: an olefinic macromonomer M6, a monomer M1 comprising a diol function F, a monomer M7 comprising a derivation functionality F' and a methacrylate or acrylate monomer M2.

[0234] In step E2, a comb copolymer is obtained having a main chain (P) carrying olefinic side chains (La), diol functions F, derivation functions F', acrylate functions (not shown).

[0235] The derivation functions F' of this copolymer are reacted with methacrylate or acrylate monomers M2 and diol M1, which leads in step E3 to a comb copolymer having a main chain (P) carrying: of methacrylate or acrylate units (not shown) of olefinic side chains (La), of diol functions (F), of side chains (Lb) comprising diol functions (F) and acrylate functions (not shown). • Properties of polydiol comb copolymers A1

[0236] Polydiol A1 copolymers are comb copolymers. Comb copolymers mean a copolymer with a main chain (also called a backbone) and oligomeric side chains. The side chains are pendant on either side of the main chain. figure 2 schematically represents a comb polymer.

[0237] The A1 copolymers have a backbone derived from polymerizable functions, in particular a backbone of methacrylate functions and preferably styrene functions, and a mixture of hydrocarbon side chains substituted or not by diol functions, some of which are oligomers and others are pendant chains of non-oligomeric monomers.

[0238] A1 copolymers have side chains which can be: chains resulting from monomers of formula (I), (II) and (X), polyolefins, in particular corresponding to macromonomers M6 of formula (IX), oligomers resulting from the polymerization of monomers of formula (I) and (II) and optionally (X).

[0239] The monomers of formula (I), (II) and (X) have polymerizable functions whose reactivity leads to the formation of copolymers whose monomers having diol functions are distributed statistically or in a gradient or in a mixed distribution, along the backbone of the copolymer, either on the main chain or on the side chains.

[0240] A1 polydiol comb copolymers have the advantage of being sensitive to external stimuli, such as temperature, pressure, and shear rate; this sensitivity results in a change in properties. In response to a stimulus, the spatial conformation of the copolymer chains is modified and the diol functions are made more or less accessible to association reactions, which can generate crosslinking, as well as to exchange reactions. These association and exchange processes are reversible. The A1 comb copolymer is a thermosensitive copolymer, i.e. it is sensitive to changes in temperature.

[0241] Advantageously, the side chains of the polydiol comb copolymer A1 of oligomer type corresponding to monomers M1, M2, M3 respectively of formula (I), (II) and (X) have a number-average molar mass ranging from 400 to 50,000, the number-average molar mass being obtained by steric exclusion chromatography measurement using a poly(methyl methacrylate) calibration.

[0242] The person skilled in the art knows how to obtain this average length by appropriately selecting the types and ratio of monomers constituting the polydiol copolymer A1. The choice of this average chain length makes it possible to obtain a polymer compatible with a hydrophobic medium, whatever the temperature at which the copolymer is dispersed, and capable of modulating the viscosity of the medium. By "hydrophobic medium" is meant a medium which has no affinity or which has a very low affinity for water, that is to say that it is not miscible in water or in an aqueous medium.

[0243] Advantageously, the polydiol copolymer A1 has a molar percentage of repeating units corresponding to monomers M1 of formula (I) in said copolymer ranging from 1 to 50%, preferably from 5 to 30%.

[0244] Advantageously, the polydiol copolymer A1 has a molar percentage of repeating units corresponding to monomers M2 of formula (II) in said copolymer ranging from 10 to 90%, preferably from 30 to 80%.

[0245] The molar percentage of repeating units in the copolymer results directly from the adjustment of the quantities of monomers used for the synthesis of the copolymer.

[0246] Advantageously, the main chain of the polydiol comb copolymer A1 has a number-average degree of polymerization ranging from 40 to 2000, preferably from 40 to 1000. In a known manner, the degree of polymerization is controlled by using a controlled radical polymerization technique, a radical polymerization technique in the presence of a transfer agent, also called telomerization under certain conditions, or by adjusting the amount of free radical source when the copolymers of the invention are prepared by conventional radical polymerization.

[0247] Advantageously, the polydiol comb copolymer A1 has a number average molar mass ranging from 5,000 to 400,000 g / mol, preferably from 10,000 to 200,000 g / mol, the number average molar mass being obtained by size exclusion chromatography measurement using a poly(methyl methacrylate) calibration.

[0248] The method of measuring size exclusion chromatography is described in the book (Fontanille, M.; Gnanou, Y., Chemistry and physicochemistry of polymers. 2nd ed.; Dunod: 2010; p 546).

[0249] Advantageously, the polydiol comb copolymer A1 has a degree of branching or degree of ramification ranging from 0.1 to 10 mol%, preferably from 0.5 to 5 mol%.

[0250] The measurement of the degree of branching is made by proton NMR and / or gel permeation chromatography (GPC) equipped with quadruple detection, namely a concentration detector, a light scattering detector, a UV-Vis detector and a viscometer. ∘ Compound A2 • Compound A2 boronic diester

[0251] In one embodiment, compound A2 comprising two boronic ester functions has the general formula (III): in which: w 1 and w 2 , identical or different, are integers equal to 0 or 1, R 4 , R 5 , R 6 and R 7 , identical or different, are chosen from the group formed by hydrogen and a hydrocarbon group comprising from 1 to 30 carbon atoms, preferably between 4 and 18 carbon atoms, even more preferably between 6 and 14 carbon atoms, said hydrocarbon group being optionally substituted by one or more groups chosen from: a hydroxyl, a -OJ group, - C(O)-OJ with J a hydrocarbon group comprising from 1 to 24 carbon atoms; L is a divalent linking group and is selected from the group consisting of a C 6 -C 18 aryl, a C 7 -C 24 aralkyl and a C 2 -C 24 hydrocarbon chain, preferably a C 6 -C 18 aryl.

[0252] By "hydrocarbon group comprising from 1 to 30 carbon atoms" is meant a linear, branched or cyclic alkyl group comprising from 1 to 30 carbon atoms, linear, branched or cyclic alkenyl group comprising from 2 to 30 carbon atoms, an aryl group comprising from 6 to 30 carbon atoms or an aralkyl group comprising from 7 to 30 carbon atoms.

[0253] By "hydrocarbon group comprising from 1 to 24 carbon atoms" is meant a linear or branched alkyl group, comprising from 1 to 24 carbon atoms or linear or branched alkenyl group, comprising from 2 to 24 carbon atoms, an aryl group comprising from 6 to 24 carbon atoms, or an aralkyl group comprising from 7 to 24 carbon atoms. Preferably, J comprises from 4 to 18 carbon atoms, preferably between 6 and 12 carbon atoms.

[0254] By "C 2 -C 24 hydrocarbon chain" is meant a linear or branched alkyl or alkenyl group comprising from 2 to 24 carbon atoms. Preferably, the hydrocarbon chain L is a linear alkyl group. Preferably the hydrocarbon chain L comprises from 6 to 16 carbon atoms.

[0255] In one embodiment of the invention, compound A2 is a compound of general formula (III) above in which: w 1 and w 2 , identical or different, are integers equal to 0 or 1; R 4 and R 6 are identical and are hydrogen atoms; R 5 and R 7 are identical and are a hydrocarbon group, preferably a linear alkyl, having from 1 to 24 carbon atoms, preferably from 4 to 18 carbon atoms, preferably from 6 to 16 carbon atoms; L is a divalent linking group and is a C 6 -C 18 aryl, preferably phenyl.

[0256] The compound A2 boronic diester of formula (III) as described above is obtained according to the method described in WO2015 / 110642 or in WO2015 / 110643. • Compound A2 poly(boronic ester) copolymer

[0257] In another embodiment, compound A2 comprising at least two boronic ester functions is a poly(boronic ester) copolymer resulting from the copolymerization of at least one monomer M4 of formula (IV) as described below with at least one monomer M5 of formula (V) as described below.

[0258] In the remainder of the application, the expressions “boronic ester copolymer” or “poly(boronic ester) copolymer” are equivalent and designate the same copolymer. ✔ Monomer M4 of formula (IV)

[0259] The monomer M4 of the compound A2 boronic ester copolymer has the general formula (IV) in which: 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 linking groups, identical or different, and are chosen from the group consisting of C 6 -C 18 aryl, C 7 -C 24 aralkyl and C 1 -C 24 alkyl, preferably M is C 6 -C 18 aryl, and R 8 is C 7 -C 24 aralkyl; X is a function chosen from the group consisting of -OC(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 chain comprising from 1 to 15 carbon atoms; R 9 is selected from the group consisting of -H, -CH 3 and -CH 2 -CH 3; preferably -H and -CH 3;R 10 and R 11 , identical or different, are chosen from the group formed by hydrogen and a hydrocarbon group comprising from 1 to 30 carbon atoms, preferably between 4 and 18 carbon atoms, even more preferably between 6 and 14 carbon atoms, said hydrocarbon group being optionally substituted by one or more groups chosen from: a hydroxyl, a -OJ group, - C(O)-OJ with J a hydrocarbon group comprising from 1 to 24 carbon atoms. ;

[0260] By "C 1 -C 24 alkyl" is meant a saturated, linear or branched hydrocarbon chain comprising from 1 to 24 carbon atoms. Preferably, the hydrocarbon chain is linear. Preferably the hydrocarbon chain comprises from 6 to 16 carbon atoms.

[0261] By "hydrocarbon chain comprising from 1 to 15 carbon atoms" is meant a linear or branched alkyl or alkenyl group, comprising from 1 to 15 carbon atoms. Preferably, the hydrocarbon chain is a linear alkyl group. Preferably, it comprises from 1 to 8 carbon atoms.

[0262] By "hydrocarbon group comprising from 1 to 30 carbon atoms" is meant a linear, branched or cyclic alkyl group comprising from 1 to 30 carbon atoms, linear, branched or cyclic alkenyl group comprising from 2 to 30 carbon atoms, an aryl group comprising from 6 to 30 carbon atoms or an aralkyl group comprising from 7 to 30 carbon atoms.

[0263] By "hydrocarbon group comprising from 1 to 24 carbon atoms" is meant a linear or branched alkyl group, comprising from 1 to 24 carbon atoms or linear or branched alkenyl group, comprising from 2 to 24 carbon atoms, an aryl group comprising from 6 to 24 carbon atoms, or an aralkyl group comprising from 7 to 24 carbon atoms. Preferably, J comprises from 4 to 18 carbon atoms, preferably between 6 and 12 carbon atoms.

[0264] In one embodiment, the monomer M4 has the general 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 linking groups and are different, M is a C 6 -C 18 aryl, preferably phenyl, R 8 is a C 7 -C 24 aralkyl, preferably benzyl; X is a function selected from the group formed by -OC(O)-, -C(O)-O-, -C(O)-N(H)- and -O-, preferably -C(O)-O- or -OC(O)-; R 9 is selected from the group formed by -H, -CH 3 , preferably -H; R 10 and R 11 are different, one of the groups R 10 or R 11 is H and the other group R 10 or R 11 is a hydrocarbon chain, preferably a linear alkyl group, having from 1 to 24 carbon atoms, preferably between 4 and 18 carbon atoms, preferably between 6 and 12 carbon atoms.

[0265] In one embodiment, the monomer M4 is a styrenic monomer. This is the case when, in formula (IV): u = 1, R9 is H and R8 represents a C 6 -C 18 aryl or a C 7 -C 24 aralkyl and the double bond of the monomer M4 of formula (IV) is directly connected to the aryl group. ✔ Synthesis of monomer M4 of formula (IV)

[0266] The monomer M4 of formula (IV) as described above is obtained according to the method described in WO2015 / 110642 or in WO2015 / 110643. > Monomer M5 of general formula (V):

[0267] The monomer M5 of the compound A2 boronic ester copolymer has the general formula (V) in which: R 12 is selected from the group consisting of -H, -CH 3 and -CH 2 -CH 3 , preferably -H and -CH 3 ; R 13 is selected from the group consisting of a C 6 -C 18 aryl, a C 6 -C 18 aryl substituted by a group R' 13 , -C(O)-OR' 13 ; -OR' 13 , -SR' 13 and -C(O)-N(H)-R' 13 with R' 13 representing H or a C 1 -C 25 alkyl group.

[0268] By “C 1 -C 25 alkyl group” is meant a saturated, linear or branched hydrocarbon chain comprising from 1 to 25 carbon atoms. Preferably, the hydrocarbon chain is linear.

[0269] By “C 6 -C 18 aryl group substituted by an R' 13 group” is meant an aromatic hydrocarbon compound comprising from 6 to 18 carbon atoms of which at least one carbon atom of the aromatic cycle is substituted by a C 1 -C 25 alkyl group as defined above.

[0270] Among the monomers of formula (V), the monomers corresponding to the formula (VA) are among the preferred: in which: R 2 is selected from the group formed by -H, -CH 3 and -CH 2 -CH 3 , preferably - H and -CH 3 ; R' 13 represents H or a C 1 -C 25 alkyl group, preferably H or a linear C 1 -C 25 alkyl, even more preferably H or a linear C 3 -C 15 alkyl, even more preferably H or a linear C 5 -C 15 alkyl.

[0271] According to another embodiment, the monomer M5 is a styrenic monomer. This is the case when, in formula (V): R 12 represents H and R 13 is chosen from the group formed by a C 6 -C 18 aryl and a C 6 -C 18 aryl substituted by a group R' 13 with R' 13 represents H or a C 1 -C 25 alkyl group and the double bond of the monomer M5 of formula (V) is directly connected to the aryl group.

[0272] Advantageously, according to this embodiment, the monomer M5 is styrene. > Obtaining the monomer M5 :

[0273] The monomers of formulas (V) and (VA) are well known to those skilled in the art. They are marketed by Sigma-Aldrich ®< and TCI ®<. > Styrenic monomer :

[0274] Advantageously, the copolymer A2 comprises at least one monomer of styrenic nature, that is to say either styrene or a styrene derivative, such as a styrene substituted by another group on the aromatic cycle.

[0275] The monomer M4 may be a styrenic monomer when, in formula (IV): u = 1, R 9 is H and R 8 represents a C 6 -C 18 aryl or a C 7 -C 24 aralkyl and the double bond of the monomer M4 of formula (IV) is directly connected to the aryl group.

[0276] The monomer M5 may also be a styrenic monomer when, in formula (V): R 12 represents H and R 13 is chosen from the group formed by a C 6 -C 18 aryl and a C 6 -C 18 aryl substituted by a group R' 13 with R' 13 represents H or a C 1 -C 25 alkyl group, and the double bond of the monomer M5 of formula (V) is directly connected to the aryl group.

[0277] When neither M4 nor M5 has a styrenic character, advantageously, the copolymer A2 comprises at least a third monomer M3 of formula (X) in which: Z 1 , Z 2 , Z 3 , identical or different, represent groups chosen from a hydrogen atom, a C 1 -C 12 alkyl, a -OZ', -C(O)-OZ' group with Z' a C 1 -C 12 alkyl.

[0278] M3 has been described in detail above for the preparation of copolymer A1. The preferred M3 monomers and their preferred amounts are the same in A2 as in A1.

[0279] Advantageously, when A2 comprises a third monomer M3 of formula (X), this monomer M3 is styrene. > Olefinic monomer :

[0280] According to one variant, the copolymer A2 comprises repeating units corresponding to at least one monomer of olefinic nature, i.e. a monomer carrying an olefin chain and optionally one or more other functional groups. In particular, according to this variant, the copolymer A2 comprises repeating units corresponding to at least one monomer M6 of general formula (IX) as described above.

[0281] The preferred variants of monomer M6 of general formula (IX) of copolymer A1 also apply to copolymer A2. • Other monomers

[0282] In addition to the repeating units detailed above, the copolymers A2 may comprise other repeating units derived from other comonomers, their proportion being at most 20% by weight, preferably at most 10% by weight and more preferably at most 5% by weight, based on the total weight of the repeating units of which the copolymer A2 is composed. • Configuration of poly(boronic ester) copolymer

[0283] Copolymer A2 may be a linear copolymer or a comb copolymer, i.e. a copolymer comprising oligomeric side chains.

[0284] In the case where the copolymer A2 is a comb copolymer, the oligomeric side chains may in particular be chains corresponding to polyolefin monomers M6 of general formula (IX) or to oligomers comprising structural units corresponding to monomers M2 of general formula (II) and possibly monomers M3 of general formula (X).

[0285] In one embodiment, a preferred comb copolymer comprises at least: repeating units corresponding to a first monomer M4 of general formula (IV) as described above; repeating units corresponding to a second monomer M5 of formula (V) as described above, preferably of formula (VA); repeating units corresponding to a third monomer M6 of formula (IX) as described above, advantageously a monomer M6 of formula (IX) in which Q 1 represents H, n=0, Q 2 is -CO-OQ' and Q' represents an olefin. > Synthesis of compound A2 copolymer poly(boronic ester)

[0286] Copolymer A2 is obtained according to the process described in WO2015 / 110642 or in WO2015 / 110643.

[0287] In the case where copolymer A2 is a comb copolymer, the person skilled in the art will apply the same derivatization or copolymerization techniques as described above for A1. > Properties of A2 poly(boronic ester) copolymer compounds

[0288] Advantageously, the chain formed by the linking of the groups R 10 , M, (R 8 ) u with u, an integer equal to 0 or 1, and X of the monomer M4 of general formula (IV) has a total number of carbon atoms ranging from 8 to 38, preferably ranging from 10 to 26.

[0289] Advantageously, the non-oligomeric side chains of the boronic ester copolymer A2 have an average length greater than 8 carbon atoms, preferably ranging from 11 to 16. This chain length makes it possible to disperse the boronic ester copolymer in a hydrophobic medium.

[0290] Advantageously, when the copolymer A2 comprises polyolefinic side chains, the non-oligomeric side chains of the copolymer A2 have an average length ranging from 1 to 8 carbon atoms.

[0291] By "average side chain length" is meant the average length of the side chains of each monomer constituting the copolymer. The side chains derived from the styrenic monomer(s) are not taken into account in the calculation of the average side chain lengths. A person skilled in the art knows how to obtain this average length by appropriately selecting the types and ratio of monomers constituting the boronic ester copolymer.

[0292] Advantageously, the boronic ester copolymer A2 has a molar percentage of monomer of formula (IV) in said copolymer ranging from 0.25 to 30%, preferably from 1 to 25%, even better from 5 to 20%.

[0293] Advantageously, the boronic ester copolymer A2 has a molar percentage of monomer of formula (IV) in said copolymer ranging from 0.25 to 30%, preferably from 1 to 25% and a molar percentage of monomer of formula (V) in said copolymer ranging from 70 to 99.75%, preferably from 75 to 99%.

[0294] Advantageously, the boronic ester copolymer A2 has a molar percentage of styrenic monomer(s), of formula (IV), (V) and / or (X), in said copolymer ranging from 2 to 50 mol%, preferably from 3 to 40%, more preferably from 5 to 35 mol%.

[0295] By "molar percentage of styrenic monomer(s)" is meant the sum of the contents of each of the styrenic monomers in the boronic ester copolymer A2, and the styrenic monomers may be: of formula (IV) when, in formula (IV): u = 1, R 9 is H and R 8 represents a C 6 -C 18 aryl or a C 7 -C 24 aralkyl and the double bond of the monomer M4 of formula (IV) is directly connected to the aryl group; of formula (V) when, in formula (V): R 12 represents H and R 13 is chosen from the group formed by a C 6 -C 18 aryl and a C 6 -C 18 aryl substituted by a group R' 13 with R' 13 represents H or a C 1 -C 25 alkyl group and the double bond of the monomer M5 of formula (V) is directly connected to the aryl group; and / or of formula (X), as explained above.

[0296] Advantageously, the poly(boronic ester) copolymer has a number-average degree of polymerization ranging from 50 to 1500, preferably from 50 to 800.

[0297] Advantageously, the poly(boronic ester) copolymer has a polydispersity index (PDI) ranging from 1.04 to 3.54; preferably ranging from 1.10 to 3.10. These values ​​are obtained by size exclusion chromatography using tetrahydrofuran as eluent and a poly(methyl methacrylate) calibration.

[0298] Advantageously, the poly(boronic ester) copolymer has a number average molar mass ranging from 10,000 to 200,000 g / mol, preferably from 25,000 to 100,000 g / mol. These values ​​are obtained by size exclusion chromatography using tetrahydrofuran as eluent and a poly(methyl methacrylate) calibration.

[0299] Compound A2, in particular the poly(boronic ester) copolymer, has the property of being able to react in a hydrophobic medium, in particular apolar, with a compound carrying diol function(s) by a transesterification reaction. This transesterification reaction can be represented according to the following diagram 9:

[0300] Thus, during a transesterification reaction, a boronic ester with a chemical structure different from the starting boronic ester is formed by exchange of hydrocarbon groups symbolized by And o Exogenous compound A4

[0301] According to one embodiment, the additive composition results from the mixing of at least: a polydiol comb copolymer A1, a copolymer A2 comprising at least two boronic ester functions and capable of associating with said polydiol copolymer A1 by at least one transesterification reaction, an exogenous polyol compound A4.

[0302] Advantageously, according to this embodiment of the invention, the molar percentage of exogenous compound A4, in the additive composition, relative to the boronic ester functions of the copolymer A2 ranges from 0.025 to 5000%, preferably from 0.1% to 1000%, even more preferably from 0.5% to 500%, even more preferably from 1% to 150%.

[0303] The exogenous compound A4 is chosen from polyols, in particular 1,2-diols and 1,3-diols as well as glycerol derivatives. For the purposes of the present invention, the term "exogenous compound" means a compound which is added to the additive composition resulting from the mixture of at least one comb copolymer A1 polydiol and at least one compound A2, in particular the poly(boronic ester) copolymer.

[0304] Compound A4 is chosen from organic compounds comprising at least one diol group and which are compatible with use in a lubricating composition. Preferably, compound A4 is chosen from hydrocarbon compounds comprising from 2 to 30 carbon atoms.

[0305] Preferably, this exogenous compound A4 is chosen from lubricating additives such as, for example, compounds known for their function as friction modifier, thickener, dispersant or detergent in lubricating compositions.

[0306] In particular, exogenous compound A4 can be chosen from 1,2-diols and 1,3-diols as well as glycerol derivatives.

[0307] According to a preferred embodiment, the exogenous compound A4 may have the general formula (VI): in which: w3 is an integer equal to 0 or 1, R 14 and R 15 , identical or different, are chosen from the group formed by hydrogen and a hydrocarbon chain having from 1 to 24 carbon atoms, preferably between 4 and 18 carbon atoms, preferably between 6 and 12 carbon atoms;

[0308] By "hydrocarbon chain comprising from 1 to 24 carbon atoms" is meant a linear or branched alkyl or alkenyl group, comprising from 1 to 24 carbon atoms. Preferably, the hydrocarbon chain is a linear alkyl group. Preferably, it comprises from 4 to 18 carbon atoms, preferably between 6 and 12 carbon atoms.

[0309] In one embodiment, the exogenous compound A4 has the general formula (VI) in which: w 3 is an integer equal to 0 or 1; R 14 and R 15 , identical or different, are chosen from the groups formed by - T, -CH 2 -OT, -CH 2 -OC(O)-T, T being chosen from the group formed by hydrogen and a hydrocarbon chain, preferably a linear alkyl chain, having from 1 to 24 carbon atoms, preferably between 4 and 18 carbon atoms, preferably between 6 and 12 carbon atoms.

[0310] In one embodiment, the exogenous compound A4 has the general formula (VI) in which: w 3 is an integer equal to 0 or 1; R 14 and R 15 are different, one of the groups R 14 or R 15 is H and the other group R 14 or R 15 is a hydrocarbon chain, preferably a linear alkyl group, having from 1 to 24 carbon atoms, preferably between 4 and 18 carbon atoms, preferably between 6 and 12 carbon atoms.

[0311] In another preferred embodiment, the exogenous compound is selected from sugars and sugar derivatives.

[0312] A person skilled in the art is able, using his general knowledge, to choose from among the sugars and sugar derivatives which are compatible with a lubricating oil.

[0313] Compounds of formula (VI) are commercially available from the following suppliers: Sigma-Aldrich ®< , Alfa Aesar ®< and TCI ®< . ∘ Exogenous compound A5

[0314] According to one embodiment, the additive composition results from the mixing of at least: a polydiol comb copolymer A1, a copolymer A2 comprising at least two boronic ester functions and capable of associating with said polydiol comb copolymer A1 by at least one transesterification reaction, an exogenous compound A5 chosen from those corresponding to formula (XI): in which: Q represents a group chosen from a hydrocarbon group comprising from 1 to 30 carbon atoms, optionally substituted by one or more groups chosen from: a hydroxyl, a -OJ group, -C(O)-OJ with J a hydrocarbon group comprising from 1 to 24 carbon atoms, G 4 , G 5 , identical or different, represent groups chosen from a hydrogen atom, a hydrocarbon chain comprising from 1 to 24 carbon atoms, a hydroxyl, a -OJ group, -C(O)-OJ with J a hydrocarbon group comprising from 1 to 24 carbon atoms, g represents 0 or 1.

[0315] Advantageously, the exogenous compound A5 corresponds to the formula (XIIA): in which: G 1 , G 2 , G 3 , G 4 , G 5 , identical or different, represent groups chosen from a hydrogen atom, a hydrocarbon chain comprising from 1 to 24 carbon atoms, a hydroxyl, a group -OJ, -C(O)-OJ with J a hydrocarbon group comprising from 1 to 24 carbon atoms, g represents 0 or 1.

[0316] According to a preferred embodiment, the molar percentage of exogenous compound A5 relative to the diol functions of the comb copolymer A1 ranges from 0.025 to 5000%, preferably from 0.1% to 1000%, even more preferably from 0.5% to 500%, even more preferably from 1% to 150%.

[0317] According to a preferred embodiment, the exogenous compound A5 is chosen from those corresponding to the formula (XII B):

[0318] According to a further preferred embodiment, the exogenous compound A5 is chosen from those corresponding to the formula (XII B) with g = 0, G 4 = H and G 5 represents a C 1 -C 24 alkyl.

[0319] By transesterification reaction, the exogenous compound A5 releases in situ the diol fragment A6 of formula (XIII): > Characteristics of the new additive compositions of the invention

[0320] The additive compositions of the invention have very varied rheological properties depending on the temperature and the proportion of compounds A1, A2 and possibly A4 and / or A5 used.

[0321] The polydiol comb copolymers A1 and the compounds A2 as defined above have the advantage of being associative and of exchanging chemical bonds in a thermoreversible manner, in particular in a hydrophobic medium, in particular an apolar hydrophobic medium.

[0322] Under certain conditions, the polydiol comb copolymers A1 and the compounds A2 as defined above can be crosslinked.

[0323] The polydiol comb copolymers A1 and the compounds A2 also have the advantage of being exchangeable.

[0324] By "associative" is meant that covalent chemical bonds of the boronic ester type are established between the polydiol comb copolymers A1 and the compounds A2 comprising at least two boronic ester functions, in particular with the poly(boronic ester) copolymer. Depending on the functionality of the comb polydiols A1 and the compounds A2 and depending on the composition of the mixtures, the formation of covalent bonds between the comb polydiols A1 and the compounds A2 may or may not lead to the formation of a three-dimensional polymer network.

[0325] By "chemical bond" we mean a covalent chemical bond of the boronic ester type.

[0326] By "exchangeable" we mean that the compounds are capable of exchanging chemical bonds with each other without the total number and nature of the chemical functions being modified. The chemical exchange reaction (transesterification) is illustrated in the following reaction scheme 10: with : R is a chemical group of compound A2, the hatched circle symbolizes the rest of the chemical structure of compound A2, the grid rectangle symbolizes the rest of the chemical structure of the comb polymer polydiol A1.

[0327] The boronic ester bonds of compounds A2, possibly the boronic ester bonds formed by transesterification reaction between the boronic esters of compounds A2 and exogenous compounds A4 and / or A5, as well as the boronic ester bonds formed by association of polydiol comb copolymers A1 and compounds A2 can exchange with the diol functions carried by compounds A3 released in situ and possibly with diol functions carried by exogenous compounds A4 and / or A5 to form new boronic ester and new diol functions without the total number of boronic ester functions and diol functions being affected. This other chemical bond exchange process is carried out by metathesis reaction, via successive exchanges of the boronic ester functions in the presence of diols. Another chemical bond exchange process is illustrated in figure 3, in which it can be observed that the polydiol copolymer A1-1, which was associated with the polymer A2-1, has exchanged two boronic ester bonds with the boronic ester copolymer A2-2. The polydiol copolymer A1-2, which was associated with the polymer A2-2, has exchanged two boronic ester bonds with the boronic ester copolymer A2-1; the total number of boronic ester bonds in the composition being unchanged and is equal to 4. The copolymer A1-1 is then associated with the polymer A2-2. The copolymer A1-2 is then with the polymer A2-1. The copolymer A2-1 has been exchanged with the polymer A2-2.

[0328] By "crosslinked" is meant a copolymer in the form of a network obtained by the establishment of bridges between the macromolecular chains of the copolymer. These linked chains are for the most part distributed in the three dimensions of space. A crosslinked copolymer forms a three-dimensional network. In practice, the formation of a copolymer network is ensured by a solubility test. It can be ensured that a copolymer network has been formed by placing the copolymer network in a solvent known to dissolve non-crosslinked copolymers of the same chemical nature. If the copolymer swells instead of dissolving, the skilled person knows that a network has been formed. figure 4 illustrates this solubility test.

[0329] By "crosslinkable" we mean a copolymer capable of being crosslinked.

[0330] By "reversibly crosslinked" is meant a crosslinked copolymer whose bridges are formed by a reversible chemical reaction. The reversible chemical reaction can move in either direction, resulting in a change in the structure of the polymer network. The copolymer can change from an initial non-crosslinked state to a crosslinked state (three-dimensional network of copolymers) and from a crosslinked state to an initial non-crosslinked state. In the context of the present invention, the bridges that form between the copolymer chains are labile. These bridges can be formed or exchanged through a chemical reaction that is reversible. In the context of the present invention, the reversible chemical reaction is a transesterification reaction between diol functions of a copolymer (copolymer A1) and boronic ester functions of a crosslinking agent (compound A2). The bridges formed are boronic ester type bonds.These boronic ester bonds are covalent and labile due to the reversibility of the transesterification reaction.

[0331] By "thermoreversibly crosslinked" is meant a copolymer crosslinked by a reversible reaction whose movement in one direction or the other is controlled by temperature. The thermoreversible crosslinking mechanism of the composition of the invention is presented schematically in Figure 5 . At low temperature, the polydiol copolymer A1 (symbolized by the copolymer carrying A functions on the Figure 5 ) is not or only slightly crosslinked by the boronic ester compounds A2 (symbolized by the compound carrying B functions on the Figure 5). When the temperature increases, the diol functions of copolymer A1 react with the boronic ester functions of compound A2 by a transesterification reaction. The polydiol copolymers A1 and the compounds A2 comprising at least two boronic ester functions then bond together and can exchange. Depending on the functionality of the polydiols A1 and the compounds A2 and depending on the composition of the mixtures, a gel may form in the medium, particularly when the medium is apolar. When the temperature decreases again, the boronic ester bonds between the polydiol copolymers A1 and the compounds A2 break, and if necessary, the composition loses its gelled character.

[0332] The amount of boronic ester bonds (or boronic ester linkage) that can be established between the polydiol comb copolymers A1 and the compounds A2 is adjusted by a person skilled in the art by means of an appropriate selection of the polydiol copolymer A1, the compound A2 and the composition of the mixture.

[0333] Furthermore, the person skilled in the art knows how to select the structure of the compound A2 according to the structure of the copolymer A1. Preferably, when in the copolymer A1 comprising at least one monomer M1 in which y=1, then the compound A2 of general formula (III) or the copolymer A2 comprising at least one monomer M4 of formula (IV) will preferably be chosen with w 1 = 1, w 2 =1 and t=1, respectively.

[0334] By controlling the association rate of the polydiol copolymer A1 and the compound A2, in particular the static poly(boronic ester) copolymer, the viscosity and rheological behavior of this composition are modulated. When present, the exogenous compound A4 and / or A5 makes it possible to modulate the viscosity of this composition according to the temperature and the desired use.

[0335] In a preferred embodiment of the invention, the exogenous compound A4 is of the same chemical nature as the diol compound A3 released in situ by transesterification reaction between the polydiol comb copolymer A1 and the compound A2, in particular the poly(boronic ester) copolymer. According to this embodiment, the total quantity of free diols present in said composition is strictly greater than the quantity of diol compounds released in situ. By "free diols" is meant the diol functions which are capable of forming a chemical bond of the boronic ester type by transesterification reaction. By "total quantity of free diols" is meant, within the meaning of the present application, the total number of diol functions capable of forming a chemical bond of the boronic ester type by transesterification.

[0336] According to this embodiment, the total quantity of free diols is always equal to the sum of the number of moles of exogenous polyol compounds A4 and the number (expressed in mol) of diol functions of the polydiol copolymer A1. In other words, if in the additive composition, we have: i moles of exogenous polyol compounds A4 and j mol of polydiol copolymers A1, the total quantity of free diols will be at any time (therefore whatever the degree of association between the polydiol copolymer A1 and the compound A2, in particular the poly(boronic ester) copolymer A2) = i + j*the average number of diols per comb polymer chain A1 (unit: mol).

[0337] The amount of diols released in situ during the transesterification reactions between A1 and A2 is equal to the number of boronic ester functions linking the copolymers A1 and A2.

[0338] The person skilled in the art knows how to select the chemical structure and the quantity of exogenous compounds A4 and / or A5 that he adds to the additive composition as a function of the molar percentage of boronic ester function of the compound A2, in particular as a function of the poly(boronic ester) copolymer, to modulate the rheological behavior of the composition.

[0339] Advantageously, the content of copolymer A1 in the composition ranges from 0.1% to 50.0% by weight relative to the total weight of the composition, preferably ranges from 0.25% to 40% by weight relative to the total weight of the final composition, more preferably from 1% to 30% by weight relative to the total weight of the final composition.

[0340] Advantageously, the content of compound A2 in the composition ranges from 0.1% to 50.0% by weight relative to the total weight of the composition, preferably ranges from 0.25% to 40% by weight relative to the total weight of the final composition, more preferably from 0.5% to 30% by weight relative to the total weight of the final composition.

[0341] In one embodiment, the content of copolymer A1 in the composition ranges from 0.5 to 50.0% by weight relative to the total weight of the composition and the content of compound A2, in particular boronic ester copolymer in the composition ranges from 0.5% to 50.0% by weight relative to the total weight of the composition.

[0342] Preferably, the mass ratio between the polydiol compound A1 and compound A2 (ratio A1 / A2) in the composition ranges from 0.005 to 200, preferably from 0.05 to 20, even more preferably from 0.1 to 10.

[0343] In one embodiment, the composition of the invention is in the form of a stock composition. By "stock composition" is meant a composition from which a person skilled in the art can make daughter solutions by taking a certain quantity of stock solution supplemented by adding a necessary quantity of diluent (solvent or other) to obtain a desired concentration. A daughter composition is therefore obtained by diluting a stock composition.

[0344] A hydrophobic medium can be a solvent, mineral oil, natural oil, synthetic oil.

[0345] In one embodiment, the composition of the invention may further comprise at least one additive selected from the group consisting of thermoplastics, elastomers, thermoplastic elastomers, thermosetting polymers, pigments, dyes, fillers, plasticizers, fibers, antioxidants, lubricant additives, compatibilizers, antifoaming agents, dispersant additives, adhesion promoters and stabilizers. > Process for the preparation of the novel additive compositions of the invention

[0346] The new additive compositions of the invention are prepared by means well known to those skilled in the art. For example, it is sufficient for those skilled in the art in particular to: taking a desired quantity of a solution comprising the polydiol comb copolymer A1 as defined above; taking a desired quantity of a solution comprising the compound A2 as defined above; in particular a desired quantity of a solution comprising the poly(boronic ester) copolymer as defined above; and optionally taking a desired quantity of a solution comprising the exogenous compound A4 and / or A5 as defined above mixing the solutions taken, either simultaneously or sequentially, to obtain the composition of the invention.

[0347] The order of addition of the compounds has no influence on the implementation of the process for preparing the additive composition.

[0348] The person skilled in the art also knows how to adjust the various parameters of the composition of the invention to obtain either a composition in which the polydiol comb copolymer A1 and the compound A2, in particular the boronic ester copolymer, are combined or a composition in which the polydiol comb copolymer A1 and the compound A2, in particular the boronic ester copolymer, are crosslinked and to modulate the degree of association or the degree of crosslinking for a given temperature of use. For example, the person skilled in the art knows how to adjust in particular, and in a non-exhaustive manner: the molar percentage of monomer M1 carrying diol functions in the polydiol comb copolymer A1; the content of styrenic monomer M3 in the polydiol comb copolymer A1; the molar percentage of olefinic macromonomer M6 in the polydiol comb copolymer A1; the molar percentage of oligomeric pendant chains comprising repeating units corresponding to monomers M2 and optionally M1 and M3 in the polydiol comb copolymer A1; the molar percentage of monomer M4 carrying boronic ester functions in the boronic ester copolymer A2; the average length of the oligomeric side chains of the polydiol copolymer A1; the average length of the non-oligomeric side chains of the polydiol copolymer A1; the average length of the side chains of the boronic ester copolymer A2; the length of monomer M4 of the boronic ester copolymer A2;the content of styrenic monomer M4 of formula (IV), or M5 of formula (V) or M3 of formula (X) in the boronic ester copolymer A2; the length of the boronic diester compound A2; the number-average degree of polymerization of the main chains of the polydiol copolymers A1 and the boronic ester copolymers A2; the number-average degree of polymerization of the side chains of the polydiol copolymers A1 and possibly the boronic ester copolymers A2; the mass percentage of the polydiol copolymer A1; the mass percentage of the boronic diester compound A2; the mass percentage of the boronic ester copolymer A2; ; and where applicable: the molar quantity of the exogenous compound A4 relative to the boronic ester functions of the compound A2, in particular of the poly(boronic ester) copolymer, the chemical nature of the exogenous compound A4; the molar percentage of exogenous compound A4; the molar quantity of the exogenous compound A5 relative to the diol functions of the diol copolymer A1, the chemical nature of the exogenous compound A5; the molar percentage of exogenous compound A5. > Use of the new compositions of the invention

[0349] The compositions of the invention can be used in all media whose viscosity varies as a function of temperature. The compositions of the invention make it possible to thicken a fluid and to modulate the viscosity as a function of the temperature of use. The additive composition according to the invention can be used in fields as varied as improved oil recovery, the paper industry, paints, food additives, cosmetic or pharmaceutical formulation. > Lubricating composition according to the invention

[0350] Another subject of the present invention relates to a lubricating composition resulting from the mixing of at least: a lubricating oil, a polydiol comb copolymer A1 as defined above, a compound A2, in particular a copolymer A2, as defined above, comprising at least two boronic ester functions and capable of associating with said polydiol comb copolymer A1 by at least one transesterification reaction, optionally an exogenous compound A4, and in particular as defined above, optionally an exogenous boronic compound A5 as defined above.

[0351] The preferences and definitions described for general formulas (I), (IA), (IB), (Ibis), (Ibis-A), (Ibis-B), (II-A), (II-B), (IX), (X) and (XII) also apply to the comb copolymer A1 polydiol used in the lubricating compositions of the invention.

[0352] The preferences and definitions described for general formulas (III), (IV), (V), (IX), (X) also apply to the boronic ester compound A2 used in the lubricating compositions of the invention.

[0353] The lubricating compositions according to the invention have an inverse behavior with respect to a change in temperature compared to the behavior of the base oil and the polymer-type rheological additives of the prior art and have the advantage that this rheological behavior can be modulated as a function of the operating temperature. Unlike the base oil which becomes more fluid as the temperature increases, the compositions of the present invention have the advantage of thickening as the temperature increases. The formation of reversible covalent bonds makes it possible to increase (reversibly) the molar mass of the polymers and therefore limits the drop in the viscosity of the base oil at high temperatures. The additional addition of diol compounds makes it possible to control the rate of formation of these reversible bonds. Advantageously, the viscosity of the lubricating composition is thus controlled and is less dependent on temperature fluctuations.Furthermore, for a given operating temperature, it is possible to modulate the viscosity of the lubricating composition and its rheological behavior by varying the amount of diol compounds added to the lubricating composition. Finally, the lubricating compositions of the invention have improved thermal stability, improved oxidation stability, an improved viscosity index, improved cycling resistance and better reproducibility of performance over time. ∘ Oil lubricant

[0354] By "oil" we mean a fatty substance that is liquid at room temperature (25°C) and atmospheric pressure (760 mm Hg or 10 5< Pa).

[0355] Lubricating oil means an oil that reduces friction between two moving parts to facilitate the operation of these parts. Lubricating oils can be of natural, mineral or synthetic origin.

[0356] Lubricating oils of natural origin can be oils of vegetable or animal origin, preferably oils of vegetable origin such as rapeseed oil, sunflower oil, palm oil, coconut oil, etc.

[0357] Mineral lubricating oils are of petroleum origin and are extracted from petroleum fractions resulting from the atmospheric and vacuum distillation of crude oil. Distillation may be followed by refining operations such as solvent extraction, dealphating, solvent dewaxing, hydrotreatment, hydrocracking, hydroisomerization, hydrofinishing, etc. For example, paraffinic mineral base oils such as Bright Stock Solvent (BSS) oil, naphthenic mineral base oils, aromatic mineral oils, hydrorefined mineral bases with a viscosity index of approximately 100, hydrocracked mineral bases with a viscosity index between 120 and 130, and hydroisomerized mineral bases with a viscosity index between 140 and 150.

[0358] Lubricating oils of synthetic origin (or synthetic base) come, as their name indicates, from chemical synthesis such as the addition of a product to itself or polymerization, or the addition of a product to another such as esterification, alkylation, fluorination, etc., from components originating from petrochemistry, carbochemistry, and mineral chemistry such as: olefins, aromatics, alcohols, acids, halogenated, phosphorus, silicon compounds, etc. As an illustration, we can cite: synthetic oils based on synthetic hydrocarbons such as polyalphaolefins (PAO), internal polyolefins (IPO), polybutenes and polyisobutenes (PIB), -alkylbenzenes, alkylated polyphenyls; synthetic oils based on esters such as diacid esters, neopolyol esters; synthetic oils based on polyglycols such as monoalkylene glycols, polyalkylene glycols and polyalkylene glycol monoethers; synthetic oils based on ester-phosphates; synthetic oils based on silicon derivatives such as silicone oils or polysiloxanes.

[0359] The lubricating oils which can be used in the composition of the invention can be chosen from any oils of groups I to V specified in the API guidelines (Base Oil Interchangeability Guidelines of the American Petroleum Institute (API)) (or their equivalents according to the ATIEL classification (Technical Association of the European Lubricants Industry) as summarized below: Saturated compound content* Sulfur content** Viscosity Index (VI)*** Group I Mineral Oils < 90 % > 0.03 % 80 ≤ VI < 120 Group II Hydrocracked Oils ≥ 90 % ≤ 0.03 % 80 ≤ VI < 120 Group III Hydrocracked or hydroisomerized oils ≥ 90 % ≤ 0.03 % ≥ 120 Group IV (PAO) Polyalphaolefins Group V Esters and other bases not included in bases groups I to IV * measured according to ASTM D2007 ** measured according to ASTM D2622, ASTM D4294, ASTM D4927 and ASTM D3120 *** measured according to ASTM D2270

[0360] The compositions of the invention may comprise one or more lubricating oils. The lubricating oil or the mixture of lubricating oils is the major ingredient in the lubricating composition. This is referred to as the lubricating base oil. By major ingredient, it is meant that the lubricating oil or the mixture of lubricating oils represents at least 51% by weight relative to the total weight of the composition.

[0361] Preferably, the lubricating oil or mixture of lubricating oils represents at least 70% by weight relative to the total weight of the composition.

[0362] In one embodiment of the invention, the lubricating oil is selected from the group consisting of oils of group I, group II, group III, group IV, group V of the API classification and a mixture thereof. Preferably, the lubricating oil is selected from the group consisting of oils of group III, group IV, group V of the API classification and a mixture thereof. Preferably, the lubricating oil is an oil of group III of the API classification.

[0363] The lubricating oil has a kinematic viscosity at 100°C measured according to ASTM D445 ranging from 2 to 150 cSt, preferably ranging from 2 to 15 cSt. ∘ Functional additives

[0364] In one embodiment, the composition of the invention may further comprise one or more functional additives selected from the group consisting of detergents, anti-wear additives, extreme pressure additives, antioxidants, viscosity index improving polymers, pour point improvers, anti-foamers, thickeners, anti-corrosion additives, dispersants, friction modifiers and mixtures thereof.

[0365] The functional additive(s) that are added to the composition of the invention are chosen according to the final use of the lubricating composition. These additives can be introduced in two different ways: either each additive is added separately and sequentially to the composition, or all the additives are added simultaneously to the composition, in which case the additives are generally available in the form of a package, called an additive package.

[0366] The functional additive or mixtures of functional additives, when present, represent from 0.1 to 10% by weight relative to the total weight of the composition. ✔ Detergents:

[0367] These additives reduce the formation of deposits on the surface of metal parts by dissolving secondary oxidation and combustion products. The detergents that can be used in the lubricating compositions according to the present invention are well known to those skilled in the art. The detergents commonly used in the formulation of lubricating compositions are typically anionic compounds comprising a long lipophilic hydrocarbon chain and a hydrophilic head. The associated cation is typically a metal cation of an alkali or alkaline-earth metal. The detergents are preferably chosen from alkali or alkaline-earth metal salts of carboxylic acids, sulfonates, salicylates, naphthenates, as well as phenate salts. The alkali and alkaline-earth metals are preferably calcium, magnesium, sodium or barium.These metal salts may contain the metal in approximately stoichiometric quantities or in excess (in quantities greater than the stoichiometric quantity). In the latter case, we are dealing with so-called overbased detergents. The excess metal giving the overbased character to the detergent is in the form of oil-insoluble metal salts, for example carbonate, hydroxide, oxalate, acetate, glutamate, preferably carbonate. ✔ Anti-wear additives and extreme pressure additives:

[0368] These additives protect friction surfaces by forming a protective film adsorbed on these surfaces. There is a wide variety of anti-wear and extreme pressure additives. Examples include phosphosulfur additives such as metal alkylthiophosphates, in particular zinc alkylthiophosphates, and more specifically zinc dialkyldithiophosphates or ZnDTP, amine phosphates, polysulfides, in particular sulfur olefins and metal dithiocarbamates. ✔ Antioxidants :

[0369] These additives delay the degradation of the composition. The degradation of the composition can result in the formation of deposits, the presence of sludge, or an increase in the viscosity of the composition. Antioxidants act as free radical inhibitors or hydroperoxide destroyers. Commonly used antioxidants include phenolic or amine antioxidants. ✔ Anti-corrosion agents:

[0370] These additives cover the surface with a film that prevents oxygen from reaching the metal surface. They can sometimes neutralize acids or certain chemicals to prevent metal corrosion. Examples include dimercaptothiadiazole (DMTD), benzotriazoles, and phosphites (capture free sulfur). ✔ Viscosity index improving polymers:

[0371] These additives ensure good cold resistance and minimal viscosity at high temperatures of the composition. Examples include polymer esters, olefin copolymers (OCP), or polymethacrylates (PMA). ✔ Pour point improvers :

[0372] These additives improve the cold behavior of the compositions, slowing down the formation of paraffin crystals. These are, for example, polyalkyl methacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes and alkylated polystyrenes. ✔ Anti-foam:

[0373] These additives counteract the effect of detergents. Examples include polymethylsiloxanes and polyacrylates. ✔ Thickeners:

[0374] Thickeners are additives used mainly for industrial lubrication and allow the formulation of lubricants with a higher viscosity than engine lubricating compositions. For example, polysiobutenes with a molar mass by weight of 10,000 to 100,000 g / mol can be mentioned. ✔ Dispersants:

[0375] These additives ensure the suspension and removal of insoluble solid contaminants consisting of secondary oxidation products that form during use of the composition. Examples include succinimides, PIB (polyisobutene) succinimides and Mannich bases. ✔ Friction modifiers ;

[0376] These additives improve the coefficient of friction of the composition. By way of illustration, mention may be made of molybdenum dithiocarbamate, amines having at least one hydrocarbon chain of at least 16 carbon atoms, esters of fatty acids and polyols such as esters of fatty acids and glycerol, in particular glycerol monooleate. ∘ Compound contents of lubricating compositions

[0377] Advantageously, the content of comb copolymer A1 in the lubricating composition ranges from 0.05% to 20% by weight relative to the total weight of the lubricating composition, preferably from 0.5% to 10% by weight relative to the total weight of the lubricating composition.

[0378] Advantageously, the content of compound A2, in particular the content of poly(boronic ester) copolymer, ranges from 0.05% to 20% by weight relative to the total weight of the lubricating composition, preferably from 0.25 to 10% by weight relative to the total weight of the lubricating composition.

[0379] Preferably, the mass ratio (ratio A1 / A2) between the polydiol compound A1 and the compound A2, in particular the poly(boronic ester) copolymer, ranges from 0.001 to 100, preferably from 0.05 to 20, even more preferably from 0.1 to 10, more preferably from 0.2 to 5.

[0380] In one embodiment, the sum of the masses of the comb copolymer A1 and of the compound A2 ranges from 0.01 to 40%, advantageously from 0.75 to 20% relative to the total mass of the lubricating composition, preferably from 2% to 15% relative to the total mass of the lubricating composition and the mass of lubricating oil ranges from 60% to 99.9% relative to the total mass of the lubricating composition.

[0381] For engine applications, advantageously, the sum of the masses of the comb copolymer A1 and of the compound A2 represents from 0.1 to 15%, relative to the total mass of the lubricating composition.

[0382] For transmission applications, advantageously, the sum of the masses of the comb copolymer A1 and of the compound A2 represents from 0.5 to 40%, relative to the total mass of the lubricating composition.

[0383] In one embodiment, the molar percentage of exogenous compound A4 in the lubricating composition ranges from 0.05% to 5000%, preferably from 0.1% to 1000%, more preferably from 0.5% to 500%, even more preferably from 1% to 150% relative to the boronic ester functions of compound A2, in particular of the poly(boronic ester) copolymer.

[0384] In one embodiment, the lubricating composition of the invention results from the mixing of: 0.05% to 20% by weight of at least one polydiol comb copolymer A1 as defined above, relative to the total weight of the lubricating composition; 0.05% to 20% by weight of at least one compound A2 as defined above, in particular poly(boronic ester) copolymer; relative to the total weight of the lubricating composition; and optionally 0.001% to 0.5% by weight of at least one exogenous compound A4 as defined above, relative to the total weight of the lubricating composition, optionally 0.001% to 0.5% by weight of at least one exogenous compound A5 as defined above, relative to the total weight of the lubricating composition, and 60% to 99.9% by weight of at least one lubricating oil as defined above, relative to the total weight of the lubricating composition.

[0385] In another embodiment, the lubricating composition of the invention results from the mixture of: 0.5% to 20% by weight of at least one polydiol comb copolymer A1 as defined above, relative to the total weight of the lubricating composition; 0.25% to 20% by weight of at least one compound A2 as defined above, in particular poly(boronic ester) copolymer; relative to the total weight of the lubricating composition; and optionally 0.001% to 0.5% by weight of at least one exogenous compound A4 as defined above, relative to the total weight of the lubricating composition, optionally 0.001% to 0.5% by weight of at least one exogenous compound A5 as defined previously, relative to the total weight of the lubricating composition, and 0.5% to 15% by weight of at least one functional additive as defined previously, relative to the total weight of the lubricating composition, and 60% to 99.25% by weight of at least one lubricating oil as defined previously, relative to the total weight of the lubricating composition. > Process for preparing the lubricating compositions of the invention

[0386] The lubricating compositions of the invention are prepared by means well known to those skilled in the art. For example, it is sufficient for those skilled in the art in particular to: taking a desired quantity of a solution comprising the polydiol comb copolymer A1 as defined above; taking a desired quantity of a solution comprising the compound A2, in particular the poly(boronic ester) copolymer A2 as defined above; optionally, taking a desired quantity of a solution comprising the exogenous compound A4 as defined above; mixing either simultaneously or sequentially the solutions taken in a lubricating base oil, to obtain the lubricating composition of the invention.

[0387] The order of addition of the compounds has no influence on the implementation of the process for preparing the lubricating composition. > Properties of the lubricating compositions according to the invention

[0388] The lubricating compositions of the invention result from the mixture of associative polymers which have the property of increasing the viscosity of the lubricating oil by associations. The lubricating compositions according to the invention have the advantage that these associations or crosslinking are thermoreversible and optionally that the rate of association or crosslinking can be controlled by adding an additional diol compound. In addition, they have improved thermal stability, an improved viscosity index, improved oxidation stability, better cycling performance, and better reproducibility of performance over time.

[0389] A person skilled in the art knows how to adjust the various parameters of the various constituents of the composition to obtain a lubricating composition whose viscosity increases when the temperature increases and to modulate its viscosity and its rheological behavior. > Method for modulating the viscosity of a lubricating composition

[0390] Disclosed herein is a method for modulating the viscosity of a lubricating composition, the method comprising at least: the provision of a lubricating composition resulting from the mixture of at least one lubricating oil, at least one polydiol comb copolymer A1 and at least one compound A2 comprising at least two boronic ester functions and capable of associating with said polydiol copolymer A1 by at least one transesterification reaction, optionally the addition to said lubricating composition of at least one exogenous compound A4, optionally the addition to said lubricating composition of at least one exogenous compound A5 chosen from boronic di- and triesters.

[0391] By "modulating the viscosity of a lubricating composition" is meant, within the meaning of the present invention, an adaptation of the viscosity at a given temperature depending on the use of the lubricating composition. This is obtained by adding an exogenous compound A4 and / or A5 as defined above. These compounds make it possible to control the degree of association and crosslinking of the two copolymers polydiol A1 and poly(boronic ester) A2. Such a method is described in detail in WO2016 / 113229. ➢ Other objects according to the invention

[0392] Another object of the present invention is the use of the lubricating composition as defined above for lubricating a mechanical part.

[0393] In the remainder of the description, the percentages are expressed by weight relative to the total weight of the lubricating composition.

[0394] The compositions of the invention can be used to lubricate the surfaces of parts conventionally found in an engine such as the piston system, rings, liners.

[0395] Thus another object of the present invention is a composition for lubricating at least one engine, said composition comprising, in particular consisting essentially of, a composition resulting from the mixture of: 85% to 99.9% by weight, advantageously from 92 to 99% by weight, of a lubricating oil, and 0.1% to 15% by weight, advantageously from 1 to 8% by weight, of a mixture of at least one comb copolymer A1 as defined above, and at least one boronic ester copolymer A2 as defined above; and optionally 0.001% to 0.1% by weight at least one exogenous compound A4 as defined previously; optionally 0.001% to 0.1% by weight at least one exogenous compound A5 as defined previously; the composition having a kinematic viscosity at 100°C measured according to standard ASTM D445 ranging from 3.8 to 26.1 cSt; the weight percentages being expressed relative to the total weight of said composition.

[0396] In one embodiment, the invention relates to a composition for lubricating at least one engine, said composition comprising, in particular consisting essentially of, a composition resulting from the mixture of: 80% to 99% by weight of a lubricating oil, and 0.1% to 15% by weight of a mixture of at least one copolymer A1 as defined above, and at least one boronic ester copolymer A2 as defined above; and optionally 0.001% to 0.1% by weight of at least one exogenous compound A4 as defined above; 0.5 to 15% by weight of at least one functional additive chosen from the group formed by detergents, anti-wear additives, extreme pressure additives, additional antioxidants, anti-corrosion additives, viscosity index improving polymers, pour point improvers, anti-foamers, thickeners, dispersants, friction modifiers and mixtures thereof; the composition having a kinematic viscosity at 100°C measured according to standard ASTM D445 ranging from 3.8 to 26.1 cSt; the weight percentages being expressed relative to the total weight of said composition.

[0397] The definitions and preferences relating to lubricating oils, comb copolymers A1, boronic ester compounds A2 and exogenous compounds A4 and / or A5 also apply to compositions for lubricating at least one engine.

[0398] Another object of the present invention is a composition for lubricating at least one transmission, such as manual or automatic gearboxes.

[0399] Thus another object of the present invention is a composition for lubricating at least one transmission, said composition comprising, in particular consisting essentially of, a composition resulting from the mixture of: 50% to 99.5% by weight of a lubricating oil, and 0.5% to 50% by weight of a mixture of at least one copolymer A1 as defined above, and at least one boronic ester copolymer A2 as defined above; and optionally 0.001% to 0.5% by weight of at least one exogenous compound A4 as defined above; optionally 0.001% to 0.5% by weight of at least one exogenous compound A5 as defined above; the composition having a kinematic viscosity at 100°C measured according to ASTM D445 standard ranging from 4.1 to 41 cSt, the weight percentages being expressed relative to the total weight of said composition.

[0400] In one embodiment of the invention, the composition for lubricating at least one transmission comprises, in particular consists essentially of, a composition resulting from the mixture of: 45% to 99.39% by weight of a lubricating oil, and 0.5% to 50% by weight of a mixture of at least one comb copolymer A1 as defined above, and at least one boronic ester copolymer A2 as defined above; and optionally 0.001% to 0.5% by weight of at least one exogenous compound A4 as defined above; optionally 0.001% to 0.5% by weight of at least one exogenous compound A5 as defined above; 0.1% to 15% by weight of at least one functional additive selected from the group consisting of detergents, anti-wear additives, extreme pressure additives, additional antioxidants, anti-corrosion additives, viscosity index improving polymers, pour point improvers, anti-foams, thickeners, dispersants, friction modifiers and mixtures thereof; the composition having a kinematic viscosity at 100°C measured according to standard ASTM D445 ranging from 4.1 to 41 cSt, the percentages by weight being expressed relative to the total weight of said composition.

[0401] The definitions and preferences relating to lubricating oils, copolymers A1, boronic ester copolymers A2 and exogenous compounds A4 and A5 also apply to compositions for lubricating at least one transmission.

[0402] The compositions of the invention can be used for engines or transmissions of light vehicles, heavy goods vehicles and also ships.

[0403] Another subject of the present invention is a method for lubricating at least one mechanical part, in particular at least one engine or at least one transmission, said method comprising a step in which said mechanical part is brought into contact with at least one lubricating composition as defined above.

[0404] The definitions and preferences relating to lubricating oils, copolymers A1, boronic ester copolymers A2 and, where appropriate, exogenous compounds A4 and A5 also apply to the lubrication process of at least one mechanical part. Figures

[0405] There figure 1 schematically represents a statistical copolymer (P1), a gradient copolymer (P2) and a block copolymer (P3), each circle represents a monomer unit. The difference in chemical structure between the monomers is symbolized by a different color (light gray / black). The figure 2 schematically represents a comb copolymer. The figure 3 schematically illustrates the boronic ester bond exchange reactions between two polydiol polymers (A1-1 and A1-2) and two boronic ester polymers (A2-1 and A2-2) in the presence of diols. figure 4illustrates and schematically represents the crosslinking of the composition according to the invention in tetrahydrofuran (THF). The Figure 5 schematically represents the behavior of the composition of the invention as a function of temperature. A copolymer (2) having diol functions (function A) can associate thermoreversibly with a copolymer (1) having boronic ester functions (function B) via a transesterification reaction. The organic group of the boronic ester functions (function B) which is exchanged during the transesterification reaction is a diol symbolized by a black crescent. A chemical bond (3) of the boronic ester type is formed with release of a diol compound. Figures 6A, 6B and 6C represent different comb copolymers A1 La figure 7 represents a synthesis scheme of comb copolymers A1 The figure 8 represents a synthesis scheme of comb copolymers A1 The Figure 9represents a graph which reports the relative viscosity of compositions B, C and D (ordinate) as a function of temperature (abscissa) from 10°C to 90°C. Figure 10 represents a graph which reports the relative viscosity of compositions F and G (ordinate) as a function of temperature (abscissa) from 10°C to 90°C over three cycles. Figure 11 represents a graph which reports the relative viscosity of compositions H, I, J (ordinate) as a function of temperature (abscissa) from 10°C to 150°C. Figure 12 represents a graph which reports the relative viscosity (ordinate) of compositions I and Id (obtained from composition I by dilution of composition I up to 2.10% by mass of copolymer) as a function of temperature (abscissa) from 10 to 150°C. Figure 13represents a graph which reports the relative viscosity (ordinate) as a function of the temperature (abscissa), of the composition Id during three successive heating-cooling cycles between 10°C and 150°C (Id-1, Id-2 and Id-3) The Figure 14 represents a graph which reports the relative viscosity (ordinate) as a function of the temperature (abscissa), of the composition J during five successive heating-cooling cycles between 10°C and 150°C (D-1, D-2, D-3, D-4 and D-5). Experimental part :

[0406] The following examples illustrate the invention without limiting it. 1. Synthesis of comb copolymers A1 carrying diol function ∘ 1.1: Synthesis of monomers 1.1.1 Synthesis of monomer M1 carrying a diol function

[0407] The synthesis of a methacrylate monomer carrying a diol function is carried out in three steps (steps 1, 2 and 3) according to the protocol below: 1st< stage :

[0408] 42.1 g (314 mmol) of 1,2,6-hexane triol (1,2,6-HexTri) are introduced into a 1L flask. 5.88 g of molecular sieve (4Å) are added followed by 570 mL of acetone. 5.01 g (26.3 mmol) of para-toluenesulfonic acid (pTSA) are then slowly added. The reaction medium is left stirring for 24 hours at room temperature. 4.48 g (53.3 mmol) of NaHCO 3 are then added. The reaction medium is left stirring for 3 hours at room temperature before being filtered. The filtrate is then concentrated under vacuum using a rotary evaporator until a suspension of white crystals is obtained. 500 mL of water is then added to this suspension. The solution thus obtained is extracted with 4 × 300 mL of dichloromethane. The organic phases are combined and dried over MgSO 4 . The solvent is then completely evaporated under vacuum at 25°C using a rotary evaporator. 2nd< stage :

[0409] 5.01 g (28.8 mmol) of the product thus obtained are introduced into a 1L flask. 4.13 g (31.9 mmol) of DIPEA and 37.9 mg (0.31 mmol) of DMAP are then introduced into the flask followed by 5.34 g (34.6 mmol) of methacrylic anhydride. The flask is then stirred at room temperature for 24 hours. 0.95 g of methanol (29.7 mmol) is then added to the solution and the flask is left stirring for an additional 1 hour. The product is then dissolved in 40 mL of hexane. The organic phase is then successively washed with 25 mL of water, 3 × 25 mL of 0.5 M aqueous hydrochloric acid solution, 3 × 25 mL of 0.5 M aqueous NaOH solution and again with 25 mL of water. The organic phase is dried over MgSO 4 , filtered and then concentrated under vacuum using a rotary evaporator to give a clear yellow liquid. 3rd< stage :

[0410] 17.23 g (71.2 mmol) of the product thus obtained are introduced into a 1L flask. 90 mL of water and 90 mL of acetonitrile are then introduced into the flask followed by 59.1 mL (159 mmol) of acetic acid. The flask is then stirred for 24 hours at 30°C, allowing a gentle stream of nitrogen to bubble through to force the elimination of acetone. The solution thus obtained is extracted with 6 × 30 mL of ethyl acetate. The organic phase is then successively washed with 5 × 30 mL of 0.5 M aqueous NaOH solution and then 3 × 30 mL of water.The organic phase is then dried over MgSO 4 , filtered and then concentrated under vacuum using a rotary evaporator to give a light yellow liquid with the following characteristics: 1< H NMR (400 MHz, CDCl3) δ: 6.02 (singlet, 1H), 5.49 (singlet, 1H), 4.08 (triplet, J = 6.4 Hz, 1H), 3.65-3.58 (multiplet, 1H), 3.57-3.50 (multiplet, 3H), 3.35 (doublet of doublets, J = 7.6 Hz and J = 11.2 Hz, 1H), 1.86 (doublet of doublets, J = 1.2 Hz and J = 1.6 Hz, 3H), 1.69-1.31 (multiplet, 6H). 1.1.2 Synthesis of Brominated Monomer (Derivation Monomer):

[0411]

[0412] 7 mL of hydroxyethyl methacrylate (58 mmol), 5.4 mL of pyridine (66 mmol), and 75 mL of dichloromethane are introduced into a 250 mL round-bottomed flask. The round-bottomed flask is then closed with a septum, degassed for 30 min by bubbling N 2 through it, and then placed in an ice-water bath. 7.7 mL of 2-bromo-2-methylpropionate bromide (64 mmol) is then added dropwise to the reaction mixture over approximately 15 minutes. The round-bottomed flask is kept stirring for 6 hours. A white precipitate forms during the reaction. The solution is then filtered to remove the solid. The solid is rinsed with dichloromethane (2 × 10 mL). The organic phase is then washed twice with 100 mL of distilled water, twice with 100 mL of a 10% NaHCO 3 solution and then twice with 100 mL of a saturated NaCl solution. The organic phase is then dried over MgSO 4 and the solvent removed using a rotary evaporator. 11.6 g of a bright yellow liquid are obtained (yield = 72%).

[0413] NMR 1< H (CDCl 3 ) : δ : 6,05 ppm (m, 1 H), 5,52 ppm (m, 1 H), 4,35 ppm (m, 4 H), 1,87 ppm (m, 3 H), 1,85 ppm (s, 6 H). 1.1.3 Synthesis of methacrylic olefin macromonomer (Monomer M6-A):

[0414]

[0415] 58.8 g (11.6 mmol) of Krasol HLBH 5000M (product supplied by Cray Valley) are dissolved in 150 g of dichloromethane (DCM). 11.9 g of methacrylic anhydride (77.3 mmol), 56.2 mg of 4-dimethylaminopyridine (0.47 mmol) and 7.37 g of trimethylamine (76 mmol) are then added. The solution is left stirring for 24 h at room temperature. The solution is then washed twice with 0.5 M aqueous sodium hydroxide solution, then twice with 0.5 M aqueous hydrochloric acid solution and finally twice with distilled water. The organic phase is dried over MgSO 4 and the solvent is evaporated using a rotary evaporator. The product is then dissolved in tetrahydrofuran (THF) before being precipitated 3 times consecutively in acetone (redissolved in THF before each precipitation). The product is dried for 18 hours under vacuum at 50°C. A colorless and translucent viscous liquid is thus obtained.The quantitative functionalization of Krasol (from alcohol to methacrylate) is confirmed in 1< H NMR by the total disappearance of the peak between 3.8 and 4.1 ppm, characteristic of the alpha protons of the alcohol function of Krasol.

[0416] NMR 1< H (CDCl 3 ): δ: 6.05 ppm (m, 1 H), 5.52 ppm (m, 1 H), 5.1-4.9 ppm (m, 1H), 1.94 ppm (s, 3 H), 2.05-0.48 ppm (1020 H), traces of DCM (5.29 ppm), THF (3.75 ppm; 1.84 ppm) and acetone (2.17ppm). 1.1.4 Synthesis of the olefin macromonomer carrying a terminal styrene function (Monomer M6-B - OLF1500-St)

[0417] The synthesis of the olefin macromonomer carrying a terminal styrene function (OLF1500-St) is carried out in two stages (Schemes 13 and 14) according to the following protocol: 1 ère< stage :

[0418] 4.0 g (27 mmol) of 4-vinylbenzoic acid (4-VBA) is dissolved in 110 mL of anhydrous dichloromethane (DCM) with a catalytic amount (15 drops) of anhydrous dimethylformamide (DMF). 5.8 mL (67 mmol) of oxalyl chloride is then added to the solution. The reaction mixture is left stirring at room temperature for 2 hours. After evaporation of the solvent under reduced pressure, the resulting yellow liquid is dried under vacuum for 2 hours. 2nd< stage :

[0419] 2.64 g (1.76 mmol) of the olefin copolymer OLF1500-OH having a number-average molar mass, M n , of 1500 g / mol and bearing a terminal primary alcohol function and 3.8 mL (27.5 mmol) of NEt 3 are dissolved in 50 mL of anhydrous DCM and the mixture is brought to approximately 0 °C using an ice bath. A solution of 4-vinylbenzoyl chloride obtained in the 1st step (27 mmol) in 30 mL of DCM is then added dropwise to the reaction mixture over approximately 25 min. The mixture is stirred in the ice bath for 1 hour, then at room temperature for 24 hours. The excess 4-vinylbenzoyl chloride is neutralized by adding 10 mL of water and leaving the reaction mixture stirring for 1 hour. The reaction mixture is then washed successively with 3 × 100 mL of 1 M HCl solution, 2 × 100 mL of 1 M NaOH solution and 1 × 100 mL of brine.After drying the organic phase on MgSO 4 , the clear yellow solution obtained is filtered on a basic alumina column. Evaporation of the DCM and drying under vacuum gave 2.80 g (97.6%) of a light yellow oil with the following characteristics: 1< H NMR (400 MHz, CDCl 3 ) δ: 8.00 (multiplet, 2H), 7.46 (doublet of doublets, J = 1.5 Hz and J = 8.3 Hz, 2H), 6.75 (doublet of doublets, J = 12.0 Hz and J = 17.5 Hz, 1H), 5.86 (doublet of doublets, J = 0.8 Hz and J = 17.7 Hz, 1H), 5.38 (doublet, J = 11.0 Hz, 1H), 4.41-4.28 (multiplet, 2H), 1.83-0.52 (multiplet, 961H). 1.1.5. Synthesis of the condensed boronic ester monomer with 1,2-dodecanediol (mEB-C 12 )

[0420] This monomer is obtained according to the protocol described in application WO2016 / 113229 (Experimental part §2.1) ∘ 1.2: Synthesis of copolymers - methods

[0421] The comb copolymers A1 of the invention are obtained using the synthesis methods described in applications WO2015 / 110642, WO2015 / 110643, WO2016 / 113229, where appropriate supplemented by the methods described in the present application.

[0422] The number-average molar mass and dispersity were obtained by size exclusion chromatography using poly(methyl methacrylate) calibration and THF as eluent. 1.2.1 Synthesis of a Brominated Main Chain (Brominated Skeleton 1) :

[0423]

[0424] 0.50 g (1.8 mmol) of brominated monomer obtained according to the protocol described above in point 1.1.2 (scheme 11), 8.52 g (59.9 mmol) of butyl methacrylate, 1.14 g (11.0 mmol) of styrene, 35.8 mg (0.13 mmol) of cumyl dithiobenzoate, 6.3 mg (0.04 mmol) of azobisisobutyronitrile (AIBN) and 5 g of anisole are introduced into a 50 mL Schlenk tube. The reaction medium is stirred and degassed for 30 minutes by bubbling nitrogen, before being brought to 65°C for a period of 16 hours. The polymer is then isolated by 3 successive precipitations in methanol and then dried for 16 hours under vacuum at 50°C. A copolymer having a number average molar mass ( M n) of 38,000 g / mol, a dispersity ( Ð) of 1.2 and a number-average degree of polymerization (DP n ) of approximately 300 is obtained. The resulting polymer contains approximately 2.3 mol% (approximately 5% by mass) of brominated methacrylate monomer. These values ​​are obtained respectively by size exclusion chromatography, using THF as eluent and a poly(methyl methacrylate) (PMMA) calibration, and by monitoring the conversion into monomers during the copolymerization. 1.2.2 Synthesis of a Brominated Main Chain (Brominated Skeleton 2) :

[0425]

[0426] 0.50 g (1.8 mmol) of brominated monomer obtained according to the protocol described above in point 1.1.2 (scheme 11), 7.45 g (52.4 mmol) of butyl methacrylate, 1.46 g (7.2 mmol) of 5,6-dihydroxyhexyl methacrylate obtained according to the protocol described in paragraph 1.1.1 above, 1.13 g (10.8 mmol) of styrene, 35.8 mg (0.13 mmol) of cumyl dithiobenzoate, 6.3 mg (0.04 mmol) of AIBN and 5 g of anisole are introduced into a 50 mL Schlenk tube. The reaction medium is stirred and degassed for 30 minutes by bubbling nitrogen before being brought to 65°C for a period of 16 hours. The polymer is then isolated by 3 successive precipitations in methanol and then dried for 16 hours under vacuum at 50°C. A copolymer presenting a M n of 46,000 g / mol, a dispersity ( Ð) of 1.2 and a number-average degree of polymerization (DP n ) of approximately 300 is obtained. The polymer thus obtained contains approximately 2.3 mol% (approximately 5% by mass) of brominated methacrylate monomer. These values ​​are respectively obtained by size exclusion chromatography, using THF as eluent and a PMMA calibration, and by monitoring the conversion into monomers during the copolymerization. 1.2.3 ATRP synthesis of the comb polydiol copolymer CPDiol-1

[0427]

[0428] 520 mg (87 µmol of brominated monomer and approximately 12 µmol of dithiobenzoate) of brominated skeleton 1 obtained according to the protocol described above, 13.4 g (39.5 mmol) of stearyl methacrylate, 0.91 g (4.5 mmol) of 5,6-dihydroxyhexyl methacrylate obtained according to the protocol described above in §1.1.1, 3 g of N,N-dimethylformamide (DMF) and 10 g of anisole are introduced into a 50 mL Schlenk flask. In parallel, 52 mg (333 µmol) of 2,2'-bipyridine, 5 mg (20 µmol) of copper (II) dibromide (CuBr 2 ) and 21 mg (147 µmol) of CuBr are dissolved in 2 g of DMF in a pillbox before sealing it with a septum. The balloon and the pillbox are degassed by bubbling nitrogen into the solutions for 30 minutes. The solution contained in the pillbox is then withdrawn and injected into the balloon using a syringe. The balloon is then placed in an oil bath thermostatically controlled at 60°C for 7 hours.The solution is then filtered through a basic alumina column to remove the copper. Finally, the polymer is isolated by 3 successive precipitations in methanol and then dried for 20 hours under vacuum at 50°C. A copolymer with a molar mass in number . M n of 105,000 g / mol, a dispersity Ð of 1.5 is obtained. These values ​​are obtained by size exclusion chromatography using THF as eluent and PMMA calibration. According to the conversion into monomers determined by 1< H NMR, the pendant chains have an average degree of polymerization in DPn number of approximately 40. 1.2.4 ATRP synthesis of comb polydiol BB:

[0429]

[0430] 522 mg (84 µmol of brominated monomer approximately 12 µmol of dithiobenzoate) of brominated skeleton 2 obtained according to the protocol described above, 9.22 g (27.2 mmol) of stearyl methacrylate, 0.80 g (3.1 mmol) of lauryl methacrylate and 6.8 g of anisole are introduced into a 50 mL Schlenk flask. In parallel, 48 mg (308 µmol) of 2,2'-bipyridine, 4 mg (18 µmol) of CuBr 2 and 19 mg (133 µmol) of CuBr are dissolved in 3.3 g of DMF in a pillbox before sealing it with a septum. The flask and the pillbox are degassed by bubbling nitrogen into the solutions for 30 minutes. The solution contained in the pillbox is then withdrawn and injected into the flask using a syringe. The flask is then placed in an oil bath thermostatically controlled at 60°C for 6.3 hours. The solution is then filtered through a basic alumina column to remove the copper. Finally, the polymer is isolated by 3 successive precipitations in methanol and then dried for 20 hours under vacuum at 50°C.A copolymer having a number average molar mass . M n of 210,000 g / mol, a dispersity Ð of 1.6 is obtained. These values ​​are obtained by size exclusion chromatography using THF as eluent and PMMA calibration. According to the conversion into monomers determined by 1< H NMR, the pendant chains have an average degree of polymerization in DPn number of about 30 units. 1.2.5 Synthesis of a comb copolymer of butyl methacrylate, methacrylate bearing a diol function and the olefin macromonomer OLF1500-St (CPDiol-2)

[0431]

[0432] Synthesis of the comb copolymer carrying diol functions in the main chain CPDiol-2 is carried out according to the following protocol (diagram 13 above): 2.50 g (17.5 mmol) of butyl methacrylate (BMA), 0.18 g (0.89 mmol) of methacrylate monomer carrying a diol function, 0.89 g (0.93 mmol) of the olefin macromonomer M6-B-OLF1500-Stobtained according to the protocol described in paragraph 1.1.4 above, 9.3 mg (0.04 mmol) of RAFT transfer agent 2-cyano-2-propyl benzodithioate (PPBD), 2.8 mg (0.02 mmol) of azobisisobutyronitrile (AIBN) and 3.6 mL of anisole are introduced into a 25 mL Schlenk tube. The reaction medium is stirred and degassed for 30 min by bubbling nitrogen, before being brought to 65°C for a period of 19 hours.

[0433] After 19h of polymerization, the Schlenk tube is placed in an ice bath to stop the polymerization. The polymer is then isolated by 2 successive precipitations in methanol cooled using an ice bath, filtration and vacuum drying at 50°C overnight. The copolymer thus obtained has a number-average molar mass (M n ) of 65,500 g / mol, a dispersity (D) of 1.25 and a number-average degree of polymerization (DP n ) of 350. The first two values ​​are obtained by size exclusion chromatography using THF as eluent and a poly(methyl methacrylate) calibration, while the DP n is obtained by 1< H NMR monitoring of the conversion into monomers during polymerization.

[0434] A poly(butyl methacrylate-co-alkyldiol methacrylate-co) copolymer is obtained. -M6-B-OLF1500-St ) CPDiol-2containing 4.5 mol% of diol repeat units (4.6% by mass) and 6.8 mol% of OLF1500-OCP pendant chains (32% by mass). The average length of the side chains is 10.9 carbon atoms. 1.2.6 Synthesis of a comb copolymer of butyl methacrylate, olefin macromonomer M6-B-OLF1500-St and polydiol polymer pendant chains (CPDiol-3)

[0435] Synthesis of comb copolymer containing olefin macromonomer M6-B-OLF1500-St and polydiol polymer pendant chains (CPDiol- 3 ) is carried out according to the following protocol (diagram 14 below): 1.2.6.1 Synthesis of a main chain containing olefin macromonomer M6-B-OLF1500-St and 2-xanthate ethyl methacrylate (backbone M6-B-OLF 1500-St-co-xanthate)

[0436] 4.00 g (28.1 mmol) of butyl methacrylate, 1.30 g (1.36 mmol) of the olefin macromonomer M6-B-OLF1500-St, 1.06 g (4.52 mmol) of 2-xanthate ethyl methacrylate (XEMA; synthesized following the protocol described in the article “Synthesis of Well-Defined Polythiol Copolymers by RAFT Polymerization” R. Nicolaÿ, Macromolecules 2012, 45, 821-827), 16.4 mg (0.074 mmol) of RAFT transfer agent 2-cyano-2-propyl benzodithioate (PPBD), 4.8 mg (0.030 mmol) of azobisisobutyronitrile (AIBN) and 6.4 mL of anisole are introduced into a 50 mL Schlenk tube. The reaction medium is stirred and degassed for 30 min by bubbling nitrogen, before being brought to 65°C for a period of 20.5 hours.

[0437] After 20.5 h of polymerization, the Schlenk tube was placed in an ice bath to stop the polymerization. The polymer was then isolated by 2 successive precipitations in ice-cooled methanol, filtration and vacuum drying at 50°C overnight. The resulting copolymer had a number-average molar mass (Mn) of 80,600 g / mol, a dispersity (Ð) of 1.61 and a number-average degree of polymerization (DPn) of 350. The first two values ​​were obtained by size exclusion chromatography using THF as eluent and a poly(methyl methacrylate) calibration, while the DPn was obtained by 1H NMR monitoring of the conversion to monomers during polymerization.

[0438] A poly(butyl methacrylate-co-ethyl 2-xanthate methacrylate-co-M6-B-OLF1500-St) copolymer is obtained, "skeleton M6-B-OLF1500-St- co-xanthate”, containing 7.9 mol% of 2-xanthate ethyl methacrylate repeating units (9.5% by mass) and 5.6 mol% of OLF1500-OCP pendant chains (27% by mass). 1.2.6.2 Synthesis of a main chain containing the olefin macromonomer M6-B-OLF1500-St and pendant acrylate functions (backbone M6-B-OLF1500-St- co -acrylate)

[0439] The xanthate functions of the copolymer "skeleton M6-B-OLF1500-St- co- xanthate" are then transformed into acrylates by Michael addition with 1,6-hexanediol diacrylate according to the following protocol: 3.70 g (1.50 mmol of XEMA functions) of "M6-B-OLF1500-St- skeleton co-xanthate" are introduced into a 250 mL Schlenk tube and dissolved in 35 mL of a THF:DMF mixture = 1:1 by volume. 0.44 g (6.00 mmol) of n-butylamine and three drops of tributylphosphine are introduced into the Schlenk tube. The reaction medium is degassed for 10 min by bubbling nitrogen, then stirred at room temperature for 2 hours. Then, a solution of 6.79 g (30.0 mmol) of 1,6-hexanediol diacrylate in 3 mL of THF is introduced and the reaction medium is left stirring at room temperature for 48 hours.

[0440] The reaction medium is then concentrated under vacuum and the polymer is isolated by 3 successive precipitations in methanol cooled using an ice bath, filtration and drying under vacuum at 50°C overnight. The copolymer thus obtained has a number-average molar mass (Mn) of 60 100 g / mol and a dispersity (D) of 1.65, as obtained by size exclusion chromatography using THF as eluent and a poly(methyl methacrylate) calibration.

[0441] The copolymer “skeleton M6-B- OLF1500-St-” is obtained. co -acrylate”, containing 5.1 mol% of repeating units bearing a pendant acrylate function (9.4% by mass) and 5.6 mol% of OLF1500-OCP pendant chains (27% by mass), as measured by 1< H NMR. 1.2.6.3 Synthesis of a side chain precursor by copolymerization of lauryl methacrylate, styrene and methacrylate carrying a diol function (polydiol side chain)

[0442] The polydiol polymer pendant chains of the comb copolymer containing the olefin macromonomer M6-B-OLF1500-St and polydiol polymer pendant chains (CPDiol- 3 ) are prepared according to the following protocol (scheme 14 above): 8.00 g (31.4 mmol) of lauryl methacrylate (LMA), 0.54 g (5.24 mmol) of styrene, 1.86 g (9.17 mmol) of methacrylate monomer carrying a diol function, 290 mg (1.31 mmol) of RAFT PPBD transfer agent, 10.8 mg (0.066 mmol) of AIBN and 3.6 mL of anisole are introduced into a 50 mL Schlenk tube. The reaction medium is stirred and degassed for 30 min by bubbling nitrogen, before being brought to 65°C for a period of 24 hours.

[0443] After 24 hours of polymerization, the Schlenk tube is placed in an ice bath to stop the polymerization. The polymer is then isolated by precipitation in ice-cooled methanol, decantation of the supernatant and drying under vacuum at 50°C overnight. The resulting copolymer has a number-average molar mass (Mn) of 9,850 g / mol, a dispersity (D) of 1.27 and a number-average degree of polymerization (DPn) of 27. The first two values ​​are obtained by size exclusion chromatography using THF as eluent and a poly(methyl methacrylate) calibration, while the DPn is obtained by 1H NMR monitoring of the conversion to monomers during polymerization.

[0444] This gives a poly(lauryl methacrylate-co-methacrylate monomer carrying a diol-co-styrene function) copolymer, “polydiol side chain”, containing 20 mol% of diol repeat units (18% by mass), 67 mol% of lauryl methacrylate repeat units (76% by mass) and 13 mol% of styrene repeat units (6.0% by mass). 1.2.6.4 Synthesis of the comb copolymer containing the olefin macromonomer M6-B-OLF1500-St and polydiol polymer pendant chains (CPDiol- 3 )

[0445] 1.07 g (0.12 mmol) of “polydiol side chain” copolymer prepared according to the protocol described in 1.2.6.3 are introduced into a 100 mL Schlenk tube and dissolved in 10 mL of a THF:DMF mixture = 2:1 by volume. 65 mg (0.88 mmol) of n-butylamine and three drops of tributylphosphine are added to the solution. The reaction medium is degassed for 5 min by bubbling nitrogen and stirred at room temperature for 2 hours. Then, a solution of 1.70 g (0.43 mmol of acrylate functions) of “M6-B-OLF1500-St- skeleton” copolymer co-acrylate» prepared according to the protocol described in 1.2.6.2 in 20 mL of a THF:DMF mixture = 2:1 by volume is added to the reaction mixture under a nitrogen atmosphere. The reaction mixture is then brought to 40°C for a period of 40 hours.

[0446] After 40 hours of reaction, 125 mg (2.03 mmol) of ethanethiol are added to the reaction medium, which is kept stirring at room temperature for 4 hours.

[0447] The comb copolymer containing the olefin macromonomer M6-B-OLF1500-St and pendant polydiol polymer chains (CPDiol- 3 ) is then isolated by 2 successive precipitations in methanol cooled using an ice bath, decantation of the supernatant and drying under vacuum at 50°C overnight. ∘ 1.3: Synthesis of comparative copolymers - methods 1.3.1 Linear polydiol-1 ( PLDiol-1 comparative) :

[0448] Linear polydiol-1 was synthesized according to the protocol described in application FR1661400 or WO2018096252A1 (experimental part §1.2.). This polydiol contains approximately 10 mol% of monomer carrying a diol function (8.6% by mass), 37 mol% of lauryl methacrylate (39.8% by mass), 28 mol% of stearyl methacrylate (40.1% by mass) and 26 mol% of styrene (11.5% by mass). The copolymer has a M n of 53,000 g / mol, a Ð of 1.3 and a DPn of 250. These values ​​are respectively obtained by size exclusion chromatography, using THF as eluent and a PMMA calibration, and by monitoring the conversion into monomers during the copolymerization. 1.3.2 Linear polydiol-2 ( PLDiol-2 comparative):

[0449] Linear polydiol-2 was synthesized according to the protocol described in application FR1661400 or WO2018096252A1 (experimental part §1.2.). This copolymer comprises 7.0 mol% of monomer carrying a diol function (6.0% by mass). The average side chain length is 10.3 carbon atoms. Its number-average molar mass is 40,000 g / mol. Its dispersity is 1.46. Its number-average degree of polymerization (DPn) is 170. The number-average molar mass and dispersity are obtained by size exclusion chromatography using a poly(methyl methacrylate) calibration. ∘ 1.4: Synthesis of boronic copolymers - methods 1.4.1 Linear poly(boronic ester)-1 (PLB1) :

[0450] A linear poly(boronic ester) was synthesized following the protocol described in application WO2016 / 113229 (experimental part §2.). This poly(boronic ester) contains approximately 4 mol% of monomer bearing a boronic ester function (8.1% by mass), 61 mol% of lauryl methacrylate (69.6% by mass) and 35 mol% of butyl methacrylate (22.3% by mass). The copolymer has a M n of 41,000 g / mol, a Ð of 1.3 and a DPn of 210. These values ​​are respectively obtained by size exclusion chromatography using THF as eluent and a PMMA calibration, and by monitoring the conversion into monomers during the copolymerization. 1.4.2 Linear statistical copolymer poly(boronic ester) ( PLB2 )

[0451] This copolymer comprises 6.0 mol% of EB-C 12 repeating units (10% by mass). The average side chain length is 12 carbon atoms. Its number-average molar mass is 45,700 g / mol. Its dispersity is 1.39. Its number-average degree of polymerization (DPn) is 175. The number-average molar mass and dispersity are obtained by size exclusion chromatography using a poly(methyl methacrylate) calibration and THF as eluent. This copolymer is obtained according to the protocol described in paragraph 2 of the Experimental Part of application WO2016 / 113229. 1.4.3 Synthesis of a comb copolymer of butyl methacrylate, styrene carrying a boronic ester function-C 12 and the olefin macromonomer M6-B- OLF 1500-St (PBB2)

[0452]

[0453] The synthesis of the comb copolymer carrying the boronic ester functions in the main chain PBB2 is carried out according to the following protocol: 2.50 g (17.5 mmol) of butyl methacrylate (BMA), 0.39 g (0.87 mmol) of the boronic ester monomer condensed with 1,2-dodecanediol (mEB-C 12 ) obtained according to the protocol described in application WO2016 / 113229 (Experimental part §2.1), 0.89 g (0.93 mmol) of the olefin macromonomer M6-B-OLF1500-St obtained according to the protocol described in paragraph 1.1.4 above, 9.3 mg (0.04 mmol) of RAFT transfer agent 2-cyano-2-propyl benzodithioate (PPBD), 2.8 mg (0.02 mmol) of AIBN and 3.8 mL of anisole are introduced into a 25 mL Schlenk tube. The reaction medium is stirred and degassed for 30 min by bubbling nitrogen, before being brought to 65°C for a period of 19 hours.

[0454] After 19 h of polymerization, the Schlenk tube is placed in an ice bath to stop the polymerization. The polymer is then isolated by precipitation in ice-cooled acetone, decantation of the supernatant and drying of the pasty polymer phase under vacuum at 50 °C overnight. The copolymer thus obtained has a number-average molar mass (M n ) of 54,800 g / mol, a dispersity (D) of 1.23 and a number-average degree of polymerization (DP n ) of 280. The first two values ​​are obtained by size exclusion chromatography using THF as eluent and a poly(methyl methacrylate) calibration, while the DP n is obtained by 1 < H NMR monitoring of the conversion into monomers during polymerization.

[0455] A poly(butyl methacrylate-co-mEB-C 12 -co-M6-B-OLF1500-St) copolymer is obtained. PBB2containing 5.7 mol% of mEB-C 12 repeat units (12% by mass) and 6.8 mol% of M6-B-OLF1500-St repeat units (30% by mass). 2. Preparation of compositions

[0456] Each polymer is dissolved in a group III base oil to obtain a 10% mass polymer solution. After complete dissolution of the polymer in the oil, these solutions serve as stock solutions for the preparation of the formulations to be studied in rheology. ∘ 2.1 Ingredients for the formulation of compositions Lubricating base oil

[0457] The lubricating base oil used in the test compositions is an API classification group III oil, marketed by SK under the name Yubase 4. It has the following characteristics: Its kinematic viscosity at 40°C measured according to ASTM D445 is 19.57 cSt; Its kinematic viscosity measured at 100°C according to ASTM D445 is 4.23 cSt; Its viscosity index measured according to ASTM D2270 is 122; Its Noack volatility in weight percentage, measured according to DIN 51581 is 15; Its flash point in degrees Celsius measured according to ASTM D92 is 230°C; Its pour point in degrees Celsius measured according to ASTM D97 is -15°C. ∘ 2.2 Formulation of compositions Preparation of Composition B

[0458] 1.60 g of group III base oil and 0.40 g of the 10% mass stock solution of comb polydiol CPDiol-1, are placed in a pillbox and vigorously mixed using a vortex mixer for 30 seconds. This formulation therefore contains 2% by mass of comb polydiol CPDiol-1. Preparation of Composition C

[0459] 1.60 g of group III base oil and 0.40 g of the 10% mass stock solution of comb polydiol BB are placed in a pillbox and vigorously mixed using a vortex mixer for 30 seconds. This formulation therefore contains 2% by mass of comb polydiol BB. Preparation of Composition D (comparative)

[0460] 1.60 g of group III base oil and 0.40 g of the 10% mass stock solution of linear polydiol-1 (PLDiol-1), are placed in a pillbox and vigorously mixed using a vortex mixer for 30 seconds. This formulation therefore contains 2% by mass of linear polydiol-1 (PLDiol-1). Preparation of Composition F (according to the invention)

[0461] 1.20 g of group III base oil, 0.40 g of the 10% mass stock solution of comb polydiol CPDiol-1, and 0.40 g of the 10% mass stock solution of linear poly(boronic ester)-1 (PLB1),are placed in a pillbox and vigorously mixed using a vortex mixer for 30 seconds. This formulation therefore contains 2% by mass of comb polydiol CPDiol-1, TD 4-37, and 2% by mass of linear poly(boronic ester)-1 (PLB1). Preparation of Composition G (according to the invention)

[0462] 1.20 g of group III base oil, 0.40 g of the 10% mass stock solution of comb polydiol BB, and 0.40 g of the 10% mass stock solution of linear poly(boronic ester)-1 (PLB1), are placed in a pillbox and vigorously mixed using a vortex mixer for 30 seconds. This formulation therefore contains 2% by mass of comb polydiol BB, and 2% by mass of linear poly(boronic ester)-1 (PLB1). Preparation of composition H (comparative) :

[0463] 0.53 g of the solution of PLB2 at 39.2% by mass in group III base oil are mixed with 6.76 g of the same base oil. This mixture is kept under vortex stirring at room temperature for 1 minute. The solution thus obtained of PLB2 is then mixed with 0.71 g of the solution of PLDiol-2 at 25.4% by mass in group III base oil. The mixture thus obtained is kept under vortex stirring at room temperature for 2 minutes. A 2.60% mass solution of linear copolymer is obtained PLB2 and 2.25% by mass of linear copolymer PLDiol-2. Preparation of composition I (according to the invention) :

[0464] 0.60 g of polydiol comb copolymer CPDiol-2 and 5.40 g of group III base oil are introduced into a flask. The mixture thus obtained is kept stirring at 100°C until the polydiol comb copolymer is completely dissolved. CPDiol-2. This gives a 10% mass solution of polydiol comb copolymer. CPDiol-2.

[0465] 0.60 g of poly(boronic ester) comb copolymer PBB2 and 5.40 g of group III base oil are introduced into a flask. The mixture thus obtained is kept stirring at 100°C until the poly(boronic ester) is completely dissolved PBB2. This gives a 10% mass solution of comb copolymer poly(boronic ester) PBB2.

[0466] 1.47 g of polydiol solution CPDiol-2 à 10% by mass in group III base oil are mixed with 2.94 g of the same base oil. This mixture is kept under vortex stirring at room temperature for 1 minute. The solution thus obtained of CPDiol-2 is then mixed with 1.47 g of the poly(boronic ester) solution PBB2 at 10% by mass in group III base oil and kept under vortex stirring at room temperature for 2 minutes. This gives the composition Icontaining 2.50% by mass of polydiol comb copolymer CPDiol-2 and 2.50% by mass of poly(boronic ester) comb copolymer PBB2. Preparation of composition J (according to the invention) :

[0467] 1.47 g of the 10% mass solution of comb-shaped polydiol CPDiol-2 prepared previously are mixed with 4.03 g of group III base oil. This mixture is kept under vortex stirring at room temperature for 1 minute. The solution thus obtained from CPDiol-2 is then mixed with 0.38 g of the solution of PLB2 at 39.2% by mass in group III base oil and kept under vortex stirring at room temperature for 2 minutes. This gives a 2.50% mass solution of polydiol comb copolymer CPDiol-2 and 2.50% by mass of linear poly(boronic ester) copolymer PLB2. 3. Rheology of polymer solutions

[0468] The relative viscosity calculated according to the following formula η relative = η solution η huile de base was chosen to represent the evolution of the viscosity of the system as a function of temperature, because this quantity directly reflects the compensation for the natural viscosity loss of a group III base oil of the polymer systems studied. 3.1 Viscosity measurement equipment and protocols (compositions A to G)

[0469] Rheological studies were carried out using a Lovis 2000 falling ball viscometer from Anton Paar.

[0470] For polymer formulations that do not form gels in a Group III base oil over the temperature range of the study, rheology measurements were performed using a DG 26.7 reference cylindrical geometry. Viscosity was measured as a function of shear rate for a temperature range from 10°C to 90°C. For each temperature, the viscosity of the system was measured as a function of shear rate from 1 to 100 s -1< . Viscosity measurements as a function of shear rate at T = 10°C, 50°C, 90°C were performed. An average viscosity was then calculated for each temperature using the measurement points located on the same plate. 3.2 Results obtained in rheology

[0471] The relative viscosity of compositions B, C and D was measured at 90°C, 50°C then 10°C ( Figure 9). All compositions contain 2% by mass of polymer. Although the two comb polydiols have similar architectures, the relative viscosity of composition B (diol functions on the pendant chains) is significantly lower than the relative viscosity of composition C (functions on the backbone). Composition D consists of a polydiol with an average degree of polymerization of approximately 250 monomer units. This polymer is therefore significantly shorter than the polymer in composition B (backbone with an average degree of polymerization of approximately 300). However, the relative viscosity of composition D is significantly higher than the relative viscosity of composition B over the entire temperature range. This means that brush diol polymers have a lesser impact on oil viscosity than linear diol polymers, especially when the pendant chains of the brushes contain the diol functions.Furthermore, composition B shows a greater increase in its relative viscosity with temperature than compositions C and D.

[0472] The relative viscosity of compositions F and G was measured at 90°C, 50°C then 10°C ( Figures 10). These two compositions were studied over 3 cooling and heating cycles from 90°C to 10°C. Regardless of the composition, the relative viscosities are very close at each temperature from one cycle to the next. This means that the rheological behavior of the formulation is reproducible over at least 3 cycles. These two compositions show a strong increase in their relative viscosity as the temperature increases. Compositions F and G have approximately the same relative viscosity at 50°C. On the other hand, composition F is less viscous at 10°C and more viscous at 90°C. This means that the formulation, in particular consisting of the comb polydiol CPDiol1, allows for a higher viscosification of apolar oils than the formulation, in particular consisting of the comb polydiol BB. 3.3 Viscosity measurement equipment and protocols (compositions H, I, J)

[0473] Rheological studies were carried out using a Couette MCR 501 stress-controlled rheometer from Anton Paar.

[0474] Rheology measurements were performed using a DG 26.7 reference cylindrical geometry. Viscosity was measured as a function of shear rate for a temperature range from 10°C to 150°C. For each temperature, the viscosity of the system was measured as a function of shear rate from 1 to 100 s -1< . Viscosity measurements as a function of shear rate at T = 10°C, 40°C, 70°C, 100°C, 130°C and 150°C were performed (ranging from 10°C to 150°C). An average viscosity was then calculated for each temperature using the measurement points located on the same plate (from 15 to 100 s -1< ).

[0475] Table 1 below shows the evolution of the absolute viscosities of compositions H to J as a function of temperature. 3.4 Results obtained in rheology compositions H, I, J)

[0476] The relative viscosities of compositions I and J were studied over a temperature range of 10° to 150°C and compared with that of composition H. The viscosity of the solution was calculated by averaging the absolute viscosities obtained for shear rates between 15 and 100 s -1< . The relative viscosity of these compositions is presented in Figure 11 . Table 1 Temperature [°C] [mPa·s] Yubase 4 [mPa·s] Composition-H [mPa·s] Composition - I [mPa·s] Composition - J 10 63,4 99,9 82,1 89,7 40 16,4 27,2 21,8 24,2 70 6,61 11,4 8,84 10,2 100 3,45 6,18 4,80 5,87 130 2,10 3,89 3,14 3,92 150 1,60 2,98 2,53 3,18

[0477] When the linear polydiol PLDiol-2 and linear poly(boronic ester) PLB2are present together in the same lubricating composition (composition H), a significant compensation of the natural viscosity loss of the group III base oil is observed over the entire temperature range studied. This results in a quasi-linear increase in relative viscosity between 10° and 150°C ( Figure 11 , dotted line-hollow squares). However, composition H also impacts the cold viscosity of the formulation, with a relative viscosity at 10°C of 1.58.

[0478] The presence of the polydiol comb copolymer CPDiol-2 and poly(boronic ester) brush copolymer PBB2in the same lubricating composition (composition I) allows a significant decrease in relative viscosity at low temperatures, up to η rel = 1.30 at 10°C. At the same time, a less significant compensation of this formulation to the natural viscosity loss of the group III base oil at high temperatures is observed compared to formulation H ( Figure 11 , dotted / solid line-stars).

[0479] Dilution of composition I up to 2.10% by mass of polydiol brush copolymer CPDiol2 and 2.10% by mass of poly(boronic ester) brush copolymer PBB2allows to further decrease the relative viscosity at 10°C up to η rel = 1.21 (Figure 12-Id, dotted line-stars). However, unlike compositions containing linear copolymers, even at this low relative viscosity at cold, composition Id preserves its viscosifying behavior at high temperatures (η rel = 1.43 at 150°C). The relative viscosity values ​​are shown for three successive heating-cooling cycles between 10°C and 150°C (Id-1, Id-2 and Id-3). These change negligibly during the 3 cycles and always give an increase in the relative viscosity between 10°C and 150°C ( Figure 13 ).

[0480] When the polydiol comb copolymer CPDiol-2 and linear poly(boronic ester) PLB2are present together in the same lubricating composition (composition J), the advantages of both systems are coupled. On this crossing of the types of associative copolymer structure, a strong compensation of the natural viscosity loss of the base oil is observed over the temperature range of 100° to 150°C ( Figure 11 , solid line-filled circles), which occurs in combination with a significant decrease in relative viscosity at low temperature compared to the formulation containing only linear copolymers.

[0481] The relative viscosity values ​​are also shown for five successive heating-cooling cycles between 10°C and 150°C (D-1, D-2, D-3, D-4 and D-5). They change very slightly over the 5 cycles and always give an increase in relative viscosity of approximately 0.65 between 10°C and 150°C, reflecting the good compensation for the natural viscosity loss of the Group III base oil over this temperature range ( Figure 14 ).

Claims

1. A composition resulting from the mixing of at least: ∘ a polydiol comb copolymer A1, statistical or gradient; and ∘ a compound A2 comprising at least two boronic ester functions; the polydiol comb copolymer A1 having a main chain and side chains, at least part of the side chains of the copolymer A1 being composed of oligomers having more than 30 carbon atoms with a degree of polymerization ranging from 5 to 1000.

2. The composition according to claim 1, wherein at least part of the side chains of the copolymer A1 is composed of oligomers having at least 50 carbon atoms, better still at least 70 carbon atoms.

3. The composition according to any of the preceding claims, wherein at least part of the side chains of the copolymer A1 is composed of oligomers having a degree of polymerization ranging from 5 to 500, better still from 5 to 200.

4. The composition according to any of the preceding claims, wherein the side chains composed of oligomers represent from 3 to 95 mass % relative to the total mass of the copolymer A1, preferably from 15 to 95 %.

5. The composition according to any of the preceding claims, wherein at least part of the side chains of the copolymer A1 is composed of oligomers O1 comprising a polyolefin fragment.

6. The composition according to claim 5, wherein the side chains comprising a polyolefin fragment represent from 3 to 85 %, preferably from 15 to 70 % by mass relative to the total mass of the copolymer A1.

7. The composition according to claim 5 or claim 6, wherein the oligomers O1 are contained in the copolymer A1 in the form of repeat units corresponding to one or more monomers M6 of general formula (IX): where: - Q1 is chosen from the group formed by -H, -CH3 and -CH2-CH3; - Q2 is chosen from a group -Q', -O-Q', -C(O)-O-Q', -O-C(O)-Q', -S- (CH2)2-C(O)-O-Q', -S-Q', -N(H)-C(O)-Q' and -C(O)-N(H)-Q' with Q' being a polyolefin, - n is an integer chosen from among 0 and 1; - A is a divalent group chosen from among -A1-, -O-(-A2-O-)n'-A1-, -C(O)-O-(-A2-O-)n'-A1-, -O- C(O)-(-A2-O-)n'-A1-, -S-(-A2-O-)n'-A1-, -N(H)-C(O)-(-A2-O-)n'-A1- and -C(O)-N(H)-(-A2-O-)n'-A1- with: A1 is a divalent radical chosen from among a C1-C30 alkyl, C6-C30 aryl, C6-C30 aralkyl; A2 is a divalent radical chosen from among C2-C4 alkyls; n' is an integer, n' is 0 or 1:

8. The composition according to any of the preceding claims, wherein the copolymer A1 comprises repeat units corresponding to at least one monomer M3 of general formula (X): where: - Z1, Z2, Z3, the same or different, represent groups chosen from among a hydrogen atom, C1-C12 alkyl, -OZ' group, -C(O)-O-Z' with Z' a C1-C12 alkyl.

9. The composition according to claim 8, wherein the monomer M3 is styrene.

10. The composition according to any of the preceding claims, wherein the copolymer A1 has a degree of branching ranging from 0.1 to 10 mole %, preferably 0.5 to 5 mole %.

11. The composition according to any of the preceding claims, wherein the comb polymer A1 comprises non-oligomeric pendant chains having a mean length ranging from 1 to 10 carbon atoms, preferably 3 to 8 carbon atoms.

12. The composition according to any of the preceding claims, wherein the main chain of the comb copolymer A1 has a number average degree of polymerization ranging from 40 to 2000, preferably from 40 to 1000.

13. The composition according to any of the preceding claims, wherein the oligomeric pendant chains of the comb copolymer A1 have a number average degree of polymerization ranging from 8 to 1000.

14. The composition according to any of the preceding claims, wherein compound A2 is chosen from among: ∘ a compound of formula (III): where: - w1 and w2, the same or different, are integers chosen from between 0 and 1; - R4, R5, R6 and R7, the same or different, represent a group chosen from among a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms optionally substituted by one or more groups chosen from among: a hydroxyl, -OJ group, -C(O)-O-J with J being a hydrocarbon group having 1 to 24 carbon atoms; - L is a divalent linker group chosen from the group formed by a C6-C18 aryl, C6-C18 aralkyl and C2-C24 hydrocarbon chain. ∘ a copolymer comprising at least ▪ repeat units corresponding to monomers M4 of formula (IV): where: - t is an integer of 0 or 1; - u is an integer of 0 or 1 - M and R8 are divalent linker groups, the same or different, chosen from the group formed by a C6-C18 aryl, C7-C24 aralkyl, and C2-C24 alkyl, preferably M is a C6-C18 aryl and R8 is a C7-C24 aralkyl; - X is a function chosen from the 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 being a hydrocarbon chain having 1 to 15 carbon atoms; - R9 is chosen from the group formed by -H-, CH3 and -CH2-CH3; - R10 and R11, the same or different, represent a group chosen from among a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms optionally substituted by one or more groups chosen from among: a hydroxyl, -OJ group, - C(O)-O-J with J being a hydrocarbon group having 1 to 24 carbon atoms; ▪ repeat units corresponding to monomers M5 of general formula (V): where: - R12 is chosen from the group formed by -H, -CH3 and CH2-CH3; - R13 is chosen from the group formed by a C6-C18 aryl, C6-C18 aryl substituted by a group R'13, -C(O)-O-R'13, -O-R'13, -S-R'13 and -C(O)-N(H)-R'13 with R'13 being a C1-C30 alkyl group.

15. A lubricant composition resulting from the mixing of at least: - one lubricating oil; and - a composition defined according to any of claims 1 to 14.