[001] The present invention relates to the use of copolymers based on monomers comprising an ester function, for instance (meth)acrylates or olefinic alkylesters, and on monomers comprising a hydrocarbon-based function comprising at least two nitrogen atoms, preferentially three nitrogen atoms, as detergent additives in a liquid fuel for an internal combustion engine. The invention also relates to some of these copolymers, based on monomers comprising an ester function and on monomers comprising a hydrocarbon-based function comprising at least three nitrogen atoms. The invention also relates to a concentrate and a fuel composition containing such a copolymer.
PRIOR ART
[002] Liquid fuels for internal combustion engines contain components that can degrade during the functioning of the engine. The problem of deposits in the internal parts of combustion engines is well known to motorists. It has been shown that the formation of these deposits has consequences on the performance of the engine and in particular has a negative impact on consumption and particle emissions. Progress in the technology of fuel additives has made it possible to confront this problem. "Detergent" additives used in fuels have already been proposed to keep the engine clean by limiting deposits ("keep-clean" effect) or by reducing the deposits already present in the internal parts of the combustion engine ("clean-up" effect). Mention may be made, for example, of US 4 171 959 which describes a detergent additive for gasoline fuel containing a quaternary ammonium function. WO 2006/135 881 describes a detergent additive containing a quaternary ammonium salt used for reducing or cleaning deposits, especially on the intake valves. However, engine technology is in constant evolution and the stipulations for fuels must evolve to cope with these technological advances of combustion engines. In particular, the novel gasoline or diesel direct-injection systems expose the injectors to increasingly severe pressure and temperature conditions, which promotes the formation of deposits. In addition, these novel injection systems have more complex geometries to optimize the spraying, in particular more numerous holes having smaller diameters, but which, on the other hand, induce greater sensitivity to deposits. The presence of deposits may impair the combustion performance and in particular increase pollutant emissions and particle emissions. Other consequences of the excessive presence of deposits have been reported in the literature, such as the increase in fuel consumption and maneuverability problems.

[003] Preventing and reducing deposits in these novel engines are essential for optimum functioning of modern engines. There is thus a need to propose detergent additives for fuel which promote optimum functioning of combustion engines, especially for novel engine technologies.
[004] There is also a need for a universal detergent additive that is capable of acting on deposits irrespective of the technology of the engine and/or the nature of the fuel. [005] US 4 508 882 describes vinyl benzotriazole monomers. These monomers may be used to form homopolymers and copolymers that can be used as UV absorbers. The examples describe random copolymers with methyl methacrylate, and with butyl acrylate. The copolymers are synthesized in toluene and are precipitated from methanol.
[006] US 2012/041 040 describes 4- and 5-vinyl isomers of 1,2,3-triazole groups, these compounds being able to be used for the synthesis of various polymers that may be used in the following applications: adhesives, coatings, encapsulation, care products, petroleum extraction, membranes, agriculture, cleaning compositions, electronics, inks. The examples describe syntheses of random copolymers with methyl acrylate and methyl methacrylate. The copolymers are synthesized without solvent and then precipitated from methanol.
[007] US 2 945 006 describes layers of gelatin comprising an adduct of an aminoguanidine and of a polymeric carbonyl compound and the use thereof as fixatives in photography. It is envisaged to use copolymers of various carbonyl monomers with C1-C4 alkyl methacrylates, in particular in the experimental section of the random copolymers with MMA. The copolymers are synthesized in dioxane and then precipitated from a basic aqueous solution with acetone.
[008] These documents do not concern the field of application of the invention and, moreover, it has been found that copolymers comprising short-chain alkyl ester units such as those described in the prior art are less efficient when compared with copolymers comprising C6-C34 alkyl ester units.
[009] WO 2015/124 584 describes a fuel additive composition comprising at least one triazole derivative and at least one additive comprising a quaternary ammonium salt. This composition is used as a detergent for limiting deposits, especially of lacquering type, in a diesel engine. The triazole derivative may be grafted onto a polyisobutylene group, but it is not a matter of copolymers comprising a repeating unit comprising three nitrogen atoms.
SUBJECT OF THE INVENTION
[010] The invention relates to the use of copolymers based on monomers comprising an ester function, for instance alkyl esters, such as alkyl (meth)acrylates, or olefinic

alkylesters, especially vinyl esters, and on monomers comprising a hydrocarbon-based group comprising at least two nitrogen atoms, preferably at least three nitrogen atoms, as detergent additives in a liquid fuel for an internal combustion engine. These copolymers may be used in the form of an additive concentrate. [011] The invention also relates to novel copolymers which may be used in this application, to a concentrate and to a fuel composition containing such copolymers. [012] The Applicant has discovered that certain families of copolymers, including the copolymers of the invention, have noteworthy properties as detergent additives in liquid fuels for internal combustion engines. The copolymers according to the invention used in these fuels can keep the engine clean, in particular by limiting or preventing the formation of deposits ("keep-clean" effect) and/or by reducing the deposits already present in the internal parts of the combustion engine ("clean-up" effect).
[013] The advantages associated with the use according to the invention of such copolymers are:
- optimum functioning of the engine,
- reduction of the fuel consumption,
- better maneuverability of the vehicle,
- reduced pollutant emissions, and
- savings due to less engine maintenance.
[014] The subject of the present invention consequently relates to the use of a copolymer as detergent additive in a liquid fuel for an internal combustion engine, said copolymer comprising at least one repeating unit comprising an alkyl ester or alkylester function and at least one repeating unit comprising at least one hydrocarbon-based group comprising at least two nitrogen atoms, preferably at least three nitrogen atoms.
[015] According to a preferred embodiment, the repeating unit comprising an alkyl ester or alkylester function is chosen from C6-C34 alkyl esters and C6-C34 alkylesters. [016] According to a preferred embodiment, the copolymer is obtained by copolymerization of at least:
- one alkyl (meth)acrylate monomer (ma), and
- one olefinic monomer (mb) comprising at least one hydrocarbon-based group comprising at least two nitrogen atoms, preferably at least three nitrogen atoms.
[017] According to a more preferred embodiment, the alkyl (meth)acrylate monomer (ma) is chosen from C1 to C34 alkyl (meth)acrylates, advantageously from C6 to C34 alkyl (meth)acrylates.
[018] According to an advantageous embodiment, the vinyl monomer (mb) comprising at least one hydrocarbon-based group comprising at least two nitrogen

atoms corresponds to formula (I) below:
in which:
R represents a hydrocarbon-based chain comprising from 1 to 24 carbon atoms, comprising at least two nitrogen atoms, preferably at least three nitrogen atoms, optionally one or more hydroxyl substituents and optionally comprising one or more groups chosen from: an ether bridge -O-, an ester bridge -COO- and a carbonyl bridge -CO-,
one or more of the nitrogen atoms may be in the form of a quaternary ammonium, R1 represents H or CH3.
[019] Advantageously, the at least two nitrogen atoms are independently present in the group R in the form of a function chosen from: an amine –NH2, an amine bridge -NH-, an imine bridge -N=, an amidine bridge -N=C-N-; a nitrile function -CN, an amide bridge -CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge -O-CO-NH-and a guanidine, alkyl guanidine, aminoguanidine, biguanidine, polyamine or polyalkylene-polyamine group, and a quaternary ammonium.
[020] According to a preferred variant, the monomer (mb) is represented by formula (Ia):
(Ia) in which:
n represents an integer chosen from 0 and 1,
Ra represents a linear, branched or cyclic C1-C12 alkyl or C2-C12 alkenyl chain, optionally comprising one or more ether bridges –O-, an amine bridge –NH-, an imine bridge –N=, a carbonyl bridge –CO-, an ester bridge –COO-, a carboxyl bridge -OCO-, an amide bridge –CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge -O-CO-NH-,
Rb represents a nitrogenous heterocycle comprising at least two nitrogen atoms, preferably at least three nitrogen atoms,

one or more of the nitrogen atoms of Ra and/or of Rb may be in the form of a
quaternary ammonium,
R1 represents H or CH3.
[021] According to this variant, advantageously, Ra represents a C1-C8 alkyl chain
optionally comprising a carbonyl bridge -CO-, and Rb is chosen from rings comprising
five atoms and rings comprising six atoms, these rings comprising two or three
nitrogen atoms, and two, three or four carbon atoms.
[022] According to another variant, the monomer (mb) is represented by formula (Ia)
in which:
n represents an integer chosen from 0 and 1,
Ra represents a group chosen from: an ether bridge –O-, an amine bridge –NH-, an
imine bridge –N=, a carbonyl bridge –CO-, an ester bridge –COO-, a carboxyl bridge
–OCO-, an amide bridge –CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge
-O-CO-NH-,
Rb represents a nitrogenous heterocycle comprising at least two nitrogen atoms,
preferably at least three nitrogen atoms,
one or more of the nitrogen atoms of Ra and/or of Rb may be in the form of a
quaternary ammonium,
R1 represents H or CH3.
[023] According to a preferred embodiment, the copolymer is a block copolymer.
[024] According to a preferred embodiment, the copolymer is a block copolymer
comprising at least:
- one block A consisting of a chain of structural units derived from the alkyl (meth)acrylate monomer (ma), and
- one block B1 consisting of a chain of structural units derived from the olefinic monomer (mb).
[025] Advantageously, the copolymer is used in a concentrate for fuel comprising one or more copolymers as described hereinabove and hereinbelow, as a mixture with an organic liquid, said organic liquid being inert with respect to the copolymer(s) and miscible with said fuel.
[026] According to another preferred embodiment, the copolymer is used in a fuel composition which comprises:
(1) a fuel derived from one or more sources chosen from the group consisting of mineral, animal, plant and synthetic sources, and
(2) one or more copolymers as described hereinabove and hereinbelow.
[027] According to a preferred embodiment, the copolymer is used in the liquid fuel to keep clean and/or to clean up at least one of the internal parts of said internal combustion engine. [028] According to a preferred embodiment, the copolymer is used in the liquid fuel

to avoid and/or reduce the formation of deposits in at least one of the internal parts of
said engine and/or to reduce the existing deposits in at least one of the internal parts
of said engine.
[029] According to a preferred embodiment, the copolymer is used to reduce the fuel
consumption of an internal combustion engine.
[030] According to a preferred embodiment, the copolymer is used to limit or reduce
or avoid or prevent pollutant emissions, in particular the particle emissions of an
internal combustion engine.
[031] According to a preferred embodiment, the internal combustion engine is a
spark ignition engine.
[032] Advantageously, according to this last embodiment, the copolymer is used to
limit or reduce or avoid or prevent the formation of deposits in at least one internal
part of a spark ignition engine chosen from the engine intake system, in particular the
intake valves, the combustion chamber, the fuel injection system, in particular the
injectors of an indirect injection system or the injectors of a direct injection system.
[033] According to another preferred embodiment, the internal combustion engine is
a diesel engine.
[034] Advantageously, according to this last embodiment, the copolymer is used to
limit or reduce or avoid or prevent the formation of deposits in the injection system of
a diesel engine, preferably on an external part of an injector of said injection system,
for example the fuel spray tip and/or on an internal part of an injector of said injection
system, for example on the surface of an injector needle.
[035] More advantageously, according to this last embodiment, the copolymer is
used to limit or reduce or avoid or prevent the formation of deposits associated with
coking and/or deposits of soap and/or lacquering type.
[036] The invention also relates to a copolymer that may be used in the uses defined
above, said copolymer comprising at least one repeating unit comprising an alkyl
ester or alkylester function and at least one repeating unit comprising at least one
hydrocarbon-based group comprising at least three nitrogen atoms.
[037] According to a first variant, this copolymer is a block copolymer.
[038] According to a preferred embodiment of the copolymer, the copolymer is
obtained by copolymerization of at least:
- one alkyl (meth)acrylate monomer (ma), and
- one olefinic monomer (mb) comprising at least one hydrocarbon-based group comprising at least three nitrogen atoms.
[039] According to a second variant, the invention relates to a copolymer that may be used in the uses defined above, said copolymer being obtained by copolymerization of at least:
- one C6 to C34 alkyl (meth)acrylate monomer,

or
- one vinyl alkylester monomer corresponding to the formula R’CO-O-
CH=CH2 with R’ a linear C6 to C34 alkyl,
and
- one olefinic monomer (mb) comprising at least one hydrocarbon-based
group comprising at least three nitrogen atoms.
[040] According to this second variant, the copolymer may be a block copolymer or may be a statistical copolymer.
[041] According to a more preferred embodiment of the copolymer, the vinyl monomer (mb) comprising at least one hydrocarbon-based group comprising at least three nitrogen atoms corresponds to formula (I) below:
in which:
R represents a hydrocarbon-based chain comprising from 1 to 24 carbon atoms,
comprising at least three nitrogen atoms, optionally one or more hydroxyl substituents
and optionally comprising one or more groups chosen from: an ether bridge -O-, an
ester bridge -COO- and a carbonyl bridge -CO-,
one or more of the nitrogen atoms may be in the form of a quaternary ammonium,
R1 represents H or CH3.
[042] Advantageously, according to this embodiment of the copolymer, the at least
three nitrogen atoms are independently present in the group R in the form of a
function chosen from: an amine –NH2, an amine bridge -NH-, an imine bridge -N=, an
amidine bridge -N=C-N-, a nitrile function -CN, an amide bridge -CONH-, a urea
bridge -NH-CO-NH-, a carbamate bridge -O-CO-NH- a guanidine, alkylguanidine,
aminoguanidine, biguanidine, polyamine or polyalkylene-polyamine group, a
quaternary ammonium.
[043] According to a first preferred variant of the copolymer, the monomer (mb) is
represented by formula (Ia):


in which:
n represents an integer chosen from 0 and 1,
Ra represents a linear, branched or cyclic C1-C12 alkyl or C2-C12 alkenyl chain, optionally comprising one or more ether bridges –O-, an amine bridge –NH-, an imine bridge –N=, a carbonyl bridge –CO-, an ester bridge –COO-, a carboxyl bridge -OCO-, an amide bridge –CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge -O-CO-NH-,
Rb represents a nitrogenous heterocycle comprising at least three nitrogen atoms, one or more of the nitrogen atoms of Ra and/or of Rb may be in the form of a quaternary ammonium, R1 represents H or CH3.
[044] Advantageously, according to this first preferred variant of the copolymer, Ra represents a C1-C8 alkyl chain optionally comprising a carbonyl bridge -CO-, and Rb is chosen from rings comprising five atoms and rings comprising six atoms, these rings comprising three nitrogen atoms, and two, three or four carbon atoms. [045] Advantageously, according to this first preferred variant of the copolymer, Rb is a triazole ring.
[046] Advantageously, according to this first preferred variant of the copolymer, the monomer (mb) is chosen from: 1-vinyl-1,2,3-triazole, 1-vinyl-1,2,4-triazole, vinylbenzotriazole, vinyladenine, vinyltriazine, 2,4-dimethyl-6-vinyltriazine, 2-vinyl-4,6-diamino-1,3,5-triazine.
[047] According to a second preferred variant of the copolymer, the monomer (mb) is represented by formula (Ib):
in which:

m represents an integer chosen from 0 and 1,
Rc represents a linear, branched or cyclic C1-C12 alkyl or C2-C12 alkenyl chain,
optionally comprising one or more groups chosen from: an ether bridge –O-, an amine
bridge –NH-, an imine bridge –N=, an ester bridge –COO-, a carbonyl bridge -CO-, an
amide bridge –CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge –O-CO-NH-,
Rd represents a group chosen from amidine, guanidine, aminoguanidine, biguanidine,
polyamine and polyalkylene-polyamine groups,
one or more of the nitrogen atoms of Rc and/or of Rd may be in the form of a
quaternary ammonium,
R1 represents H or CH3.
[048] According to a second preferred variant of the copolymer, the monomer (mb) is
represented by formula (Ib) in which:
m represents an integer chosen from 0 and 1,
Rc represents a group chosen from: an ether bridge –O-, an amine bridge –NH-, an
imine bridge –N=, an ester bridge –COO-, a carbonyl bridge –CO-, an amide bridge –
CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge –O-CO-NH-,
Rd represents a group chosen from amidine, guanidine, aminoguanidine, biguanidine,
polyamine and polyalkylene-polyamine groups,
one or more of the nitrogen atoms of Rc and/or of Rd may be in the form of a
quaternary ammonium,
R1 represents H or CH3.
[049] According to a preferred embodiment of the copolymer, the copolymer is a
block copolymer comprising at least:
- one block A consisting of a chain of structural units derived from the alkyl (meth)acrylate monomer (ma), and
- one block B1 consisting of a chain of structural units derived from the olefinic monomer (mb).
[050] Advantageously, according to this last embodiment, the copolymer is obtained
by block polymerization, preferably by controlled block polymerization, optionally
followed by one or more post-functionalizations.
[051] Advantageously, according to this last embodiment, the copolymer comprises
at least one sequence of blocks AB1, AB1A or B1AB1 in which said blocks A and B1
form a chain without the presence of an intermediate block of different chemical
nature.
[052] A subject of the invention is also a concentrate for fuel comprising one or more
copolymers as described hereinabove and hereinbelow, as a mixture with an organic
liquid, said organic liquid being inert with respect to the copolymer(s) and miscible
with said fuel.
[053] A subject of the invention is also a fuel composition which comprises:

(1) a fuel derived from one or more sources chosen from the group consisting of mineral, animal, plant and synthetic sources, and
(2) one or more copolymers as described hereinabove and hereinbelow.
[054] According to a preferred embodiment, the fuel composition comprises at least 5 ppm of copolymer(s) (2).
DETAILED DESCRIPTION
[055] Other advantages and characteristics will emerge more clearly from the
description that follows. The particular embodiments of the invention are given as
nonlimiting examples.
[056] According to the invention, the copolymer comprises at least one repeating unit
comprising an alkyl ester or alkylester function and at least one repeating unit
comprising at least one hydrocarbon-based group comprising at least two nitrogen
atoms.
[057] The term "alkyl ester" denotes an alkyl carboxylate A1-CO-O-A2 with A2 an
alkyl and A1 any group.
[058] The term "alkylester" denotes an alkylcarboxylate A1-CO-O-A2 with A1 an
alkyl and A2 any group.
[059] Advantageously, the repeating unit comprising an alkyl ester or alkylester
function is an olefinic unit.
[060] Advantageously, the repeating unit comprising at least one hydrocarbon-based
group comprising at least two nitrogen atoms is an olefinic unit.
[061] According to a preferred embodiment, the olefinic repeating unit comprising an
alkyl ester or alkylester function is chosen from C6-C34 alkyl esters and C6-C34
alkylesters.
[062] Advantageously, the olefinic repeating unit comprising an alkyl ester or
alkylester function is chosen from:
• C6 to C30, more preferentially C6 to C24, even more preferentially C8 to C22 alkyl esters, and
• C6 to C30, more preferentially C6 to C24, even more preferentially C8 to C22 alkylesters.
[063] For example, the repeating unit comprising an alkyl ester function may be
derived from an alkyl acrylate or alkyl methacrylate monomer. For example, the
repeating unit comprising an alkylester function may be derived from a vinyl alkylester
or 2-propenyl alkylester monomer.
[064] Preferably, the repeating unit comprising an alkyl ester function is derived from
at least one monomer chosen from alkyl acrylate and alkyl methacrylate monomers
(ma).

[065] For reasons of simplicity, in the rest of the description, the term "alkyl (meth)acrylate" denotes a monomer chosen from alkyl acrylates and alkyl methacrylates.
[066] The monomer (ma) is preferably chosen from C1 to C34, preferably C4 to C30, more preferentially C6 to C24 and even more preferentially C8 to C22 alkyl (meth)acrylates. The alkyl radical of the alkyl acrylate or methacrylate is linear, branched, cyclic or acyclic, preferably acyclic.
[067] Among the alkyl (meth)acrylates that may be used in the manufacture of the copolymer of the invention, mention may be made, in a nonlimiting manner, of: n-octyl acrylate, n-octyl methacrylate, n-decyl acrylate, n-decyl methacrylate, n-dodecyl acrylate, n-dodecyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isooctyl acrylate, isooctyl methacrylate, isodecyl acrylate, isodecyl methacrylate. [068] The vinyl alkylester monomers correspond to the formula R’CO-O-CH=CH2, in which R’ represents a linear, branched, cyclic or acyclic, preferably acyclic, alkyl group.
[069] Preferably, R' is a linear C1 to C34, preferably C4 to C30, more preferentially C6 to C24 and even more preferentially C8 to C22 alkyl.
[070] Among the vinyl alkylester monomers, examples that may be mentioned include vinyl octanoate, vinyl decanoate, vinyl dodecanoate, vinyl tetradecanoate, vinyl hexadecanoate, vinyl octadecanoate and vinyl docosanoate. [071] Preferably, the repeating unit comprising at least one hydrocarbon-based group comprising at least two nitrogen atoms is derived from at least one olefinic monomer (mb) comprising at least one hydrocarbon-based group comprising at least two nitrogen atoms, preferably at least three nitrogen atoms.
[072] Preferably, the olefinic monomer (mb) comprising at least one hydrocarbon-based group comprising at least two nitrogen atoms corresponds to formula (I) below:

in which:
R represents a linear, branched or cyclic, saturated or unsaturated hydrocarbon-based chain comprising from 1 to 24 carbon atoms, comprising at least two nitrogen atoms, preferably at least three nitrogen atoms, and optionally one or more hydroxyl (OH) substituents and optionally comprising one or more groups chosen from: an ether bridge -O-, an ester bridge -COO-, a carbonyl bridge -CO-, one or more of the nitrogen atoms may be in the form of a quaternary ammonium,

R1 represents H or CH3.
[073] The at least two nitrogen atoms, preferably the at least three nitrogen atoms,
may be independently present in the group R in the form of an amine function –NH2,
an amine bridge -NH-, an imine bridge -N=, an amidine bridge -N=C-NH-, a nitrile
function -CN, an amide bridge -CONH-, a urea bridge -NH-CO-NH-, a carbamate
bridge -O-CO-NH-, a guanidine group, an alkylguanidine, aminoguanidine,
biguanidine, polyamine or polyalkylene-polyamine group, or a quaternary ammonium
function.
[074] The term "hydrocarbon-based chain" means a chain constituted exclusively of
carbon and hydrogen atoms, said chain possibly being linear or branched, cyclic,
polycyclic or acyclic, saturated or unsaturated, and optionally aromatic or
polyaromatic. A hydrocarbon-based chain may comprise a linear or branched part
and a cyclic part. It may comprise an aliphatic part and an aromatic part. The
definition of R also includes saturated or unsaturated heterocyclic groups, comprising
an alkyl part and at least one function chosen from an ether bridge -O-, an amine
bridge -NH-, an imine bridge -N=C, an amidine bridge -N=C-NH-, an amide bridge -
CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge -O-CO-NH-, an ester bridge
-COO-, a carbonyl bridge -CO-, a guanidine group, an alkylguanidine,
aminoguanidine, biguanidine, polyamine or polyalkylene-polyamine group, and a
quaternary ammonium group.
[075] Among the quaternary ammonium groups, mention may be made of those
obtained by quaternization of primary, secondary or tertiary amines, according to any
known process.
[076] At least one of the nitrogen atoms may in particular be in the form of a
quaternary ammonium function obtained by quaternization of at least one amine,
imine, amidine, guanidine, aminoguanidine or biguanidine function; the heterocyclic
groups containing from 3 to 34 atoms and at least one nitrogen atom.
[077] Advantageously, at least one of the nitrogen atoms may in particular be in the
form of a group containing at least one quaternary ammonium function obtained by
quaternization of a tertiary amine.
[078] According to a particular embodiment, the quaternary ammonium is chosen
from iminium, amidinium, formamidinium, guanidinium and biguanidinium quaternary
ammoniums.
[079] According to another particular embodiment, at least one nitrogen atom may
be in the form of a function containing at least one quaternary ammonium function
chosen from heterocyclic groups containing from 3 to 34 atoms and at least one
nitrogen atom, preferably from pyrrolinium, pyridinium, imidazolium, triazolium,
triazinium, oxazolium and isoxazolium quaternary ammoniums.
[080] According to a particular embodiment, at least one nitrogen atom may in

particular be in the form of a function containing at least one quaternary ammonium function, preferably comprising at least one linear or branched, cyclic or acyclic, preferably acyclic, C1 to C10 and preferably C1 to C4 hydrocarbon-based chain, said chain optionally comprising one or more oxygen atoms in the form of an ether function or as a substitution, preferably as a substitution. The hydrocarbon-based chain may be, for example, an alkyl chain substituted with a hydroxyl group, this type of quaternary ammonium possibly being obtained by reaction of a tertiary amine with an epoxide according to any known process.
[081] Advantageously, at least one of the nitrogen atoms is in the form of a trialkylammonium function. The alkyl substituents of the trialkylammonium are preferably chosen from alkyl groups containing from 1 to 10 and preferably from 1 to 4 carbon atoms, and being linear or branched, cyclic or acyclic, preferably acyclic. [082] According to one variant, at least one of the nitrogen atoms may in particular be in the form of a function chosen from quaternary ammoniums substituted with at least one linear or branched, cyclic or acyclic, preferably acyclic, C1 to C10 and even more preferentially C1 to C4 hydrocarbon-based chain, preferably alkyl, comprising one or more hydroxyl groups.
[083] Preferably, R is chosen from hydrocarbon-based chains comprising from 1 to 24 carbon atoms, comprising at least two nitrogen atoms, preferably at least three nitrogen atoms, and not comprising any oxygen atoms.
[084] According to a first embodiment of the invention, R represents a nitrogenous heterocycle, optionally connected to the olefinic function via an alkyl chain. [085] According to this variant, the monomer (mb) corresponding to formula (I) is advantageously represented by formula (Ia):

(Ia)
in which:
n represents an integer chosen from 0 and 1,
Ra represents a linear, branched or cyclic C1-C12 alkyl or C2-C12 alkenyl chain, optionally comprising one or more ether bridges –O-, an amine bridge –NH-, an imine bridge –N=, a carbonyl bridge –CO-, an ester bridge –COO-, a carboxyl bridge -OCO-, an amide bridge –CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge -O-CO-NH-, Rb represents a nitrogenous heterocycle comprising at least two nitrogen atoms;

advantageously, Rb represents a nitrogenous heterocycle comprising at least three
nitrogen atoms,
one or more of the nitrogen atoms of Ra and/or of Rb may be in the form of a
quaternary ammonium,
R1 represents H or CH3.
[086] According to another variant, the monomer (mb) corresponding to formula (I) is
advantageously represented by formula (Ia) in which:
n represents an integer chosen from 0 and 1,
Ra represents a group chosen from one or more ether bridges –O-, an amine bridge –
NH-, an imine bridge –N=, a carbonyl bridge –CO-, an ester bridge -COO-, a carboxyl
bridge –OCO-, an amide bridge –CONH-, a urea bridge -NH-CO-NH-, a carbamate
bridge –O-CO-NH-,
Rb represents a nitrogenous heterocycle comprising at least two nitrogen atoms;
advantageously, Rb represents a nitrogenous heterocycle comprising at least three
nitrogen atoms,
one or more of the nitrogen atoms of Ra and/or of Rb may be in the form of a
quaternary ammonium,
R1 represents H or CH3.
[087] Preferably, in formula (Ia), n represents 0.
[088] When n = 1, Ra preferably represents a linear or branched C1-C8 alkyl chain,
optionally comprising a carbonyl bridge.
[089] Rb may be a monocycle or a polycyclic compound.
[090] Preferably, Rb is monocyclic or bicyclic, and even more preferentially Rb is
monocyclic.
[091] Rb may be saturated or unsaturated, optionally aromatic.
[092] Preferably, Rb represents a nitrogenous heterocycle comprising at least two
nitrogen atoms and at least two carbon atoms. Even more advantageously, Rb
represents a nitrogenous heterocycle comprising at least three nitrogen atoms and at
least two carbon atoms.
[093] Advantageously, Rb comprises at least five atoms. Even more preferentially,
Rb is chosen from rings comprising five atoms and rings comprising six atoms.
[094] Even more advantageously, Rb is chosen from rings comprising five atoms
and rings comprising six atoms, these rings comprising two or three nitrogen atoms,
and two, three or four carbon atoms.
[095] Among the saturated nitrogenous heterocycles, examples that may be
mentioned include the following rings:


[096] Among the unsaturated nitrogenous heterocycles, mention may be made of the following rings:

5 [097] As examples of monomers of formula (Ia) in which Rb represents a nitrogenous bicyclic group, mention may be made of 6-amino-9-vinylbenzylpurine (or 9-vinylbenzyladenine), the synthesis of which is described in US 6 870 021, and 9-vinyladenine, the synthesis of which is described in US 3 664 991. [098] Preferably, Rb comprises at least one unsaturation; better still, Rb comprises
10 at least two unsaturations.
[099] Even more advantageously, Rb is chosen from rings comprising five atoms and rings comprising six atoms chosen from carbon and nitrogen, these rings comprising two or three nitrogen atoms, two, three or four carbon atoms, and at least two unsaturations and the quaternary ammoniums derived therefrom by
15 quaternization of a nitrogen atom.
[100] Very advantageously, according to this variant, the monomer mb is chosen from:
20

N-vinylimidazole, 1-vinyl-1,2,4-triazole and 1-vinyl-1,2,3-triazole
and the quaternary ammoniums derived therefrom by quaternization of a nitrogen
atom.
[101] Advantageously, the monomer mb is chosen from 1-vinyl-1,2,4-triazole and
1-vinyl-1,2,3-triazole; preferably, the monomer mb is 1-vinyl-1,2,4-triazole and the
quaternary ammoniums derived therefrom by quaternization of a nitrogen atom.
[102] According to a second embodiment of the invention, R represents a linear,
branched or cyclic nitrogenous hydrocarbon-based chain. Preferably, according to
this variant, the at least two nitrogen atoms, preferably the at least three nitrogen
atoms, form part of a function chosen from: a guanidine, alkylguanidine,
aminoguanidine or biguanidine function, an amidine function, a polyamine or
polyalkylene-polyamine chain and the quaternary ammoniums derived therefrom by
quaternization of a nitrogen atom.
[103] According to this variant, the monomer (mb) corresponding to formula (I) is
advantageously represented by formula (Ib):
in which:
m represents an integer chosen from 0 and 1,
Rc represents a linear, branched or cyclic C1-C12 alkyl or C2-C12 alkenyl chain,
optionally comprising one or more groups chosen from: an ether bridge –O-, an amine
bridge –NH-, an imine bridge –N=, an ester bridge –COO-, a carbonyl bridge -CO-, an
amide bridge –CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge –O-CO-NH-,
Rd represents a group chosen from amidine, guanidine, alkylguanidine,
aminoguanidine, biguanidine, polyamine and polyalkylene-polyamine groups,
one or more of the nitrogen atoms of Rc and/or of Rd may be in the form of a
quaternary ammonium,
R1 represents H or CH3.
[104] According to another variant, the monomer (mb) corresponding to formula (I) is
advantageously represented by formula (Ib) in which:
m represents an integer chosen from 0 and 1,
Rc represents a linear, branched or cyclic C1-C12 alkyl or C2-C12 alkenyl chain,
optionally comprising one or more groups chosen from: an ether bridge –O-, an amine
bridge –NH-, an imine bridge –N=, an ester bridge –COO-, a carbonyl bridge -CO-, an
amide bridge –CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge –O-CO-NH-,

Rd represents a group chosen from amidine, guanidine, alkylguanidine,
aminoguanidine, biguanidine, polyamine and polyalkylene-polyamine groups,
one or more of the nitrogen atoms of Rc and/or of Rd may be in the form of a
quaternary ammonium,
R1 represents H or CH3.
[105] Preferably, according to this variant, Rc represents a linear or branched C1-C8
alkyl chain.
[106] Among the groups Rd, mention may be made especially of:
• amidine: -(C=NH)-NH2; -(C=NH)-NR’H; -(C=NH)-NR’R’’; -(C=NR’)-NH2;
-(C=NR’)-NR’’H; -(C=NR’)-NR’’R’’’; -N=CH(NH2); -N=CR’(NH2); -N=CH(NR’H); -N=CR’(NR’H); -N=CH(NR’R’’); -N=CR’(NR’’R’’’);
• guanidine: -NH-(C=NH)-NH2; -NH-(C=NH)-NHR’; -N=C(NH2)2;
-N=C(NR’H)2;-N=C(NR’R’’)2; -N=C(NR’H)( NR’’H);
• aminoguanidine: -NH-(C=NH)-NH-NH2; -NH-(C=NH)-NH-NHR’;
-N=C(NH2)(NH-NH2); -N=C(NR’H)(NH-NH2); -N=C(NR’H)(NR’-NH2); -N=C(NR’R’’)(NH-NH2); -N=C(NR’R’’) (NR’-NH2);
• biguanidine: -NH-(C=NH)-NH-(C=NH)-NH2; -NH-(C=NH)-NH-(C=NH)-NHR’;
-N=C(NH2)-NH-(C=NH)-NH2; -N=C(NH2)-NH-(C=NR’)-NH2; -N=C(NH2)-NH-(C=NH)-NR’H; -N=C(NH2)-NH-(C=NR’)-NR’’H; -N=C(NH2)-NH-(C=NH)-NR’R’’; -N=C(NH2)-NH-(C=NR’)-NR’’R’’’; -N=C(NR’H)-NH-(C=NH)-NH2; -N=C(NR’H)-NH-(C=NR’’)-NH2; -N=C(NR’H)-NH-(C=NH)-NR’’H; -N=C(NR’H)-NH-(C=NR’’)-NR’’’H; -N=C(NR’H)-NH-(C=NH)-NR’’R’’’; -N=C(NR’H)-NH-(C=NR’’)-NR’’’R’’’’; -N=C(NR’R’’)-NH-(C=NH)-NH2; -N=C(NR’R’’)-NH-(C=NR’’’)-NH2; -N=C(NR’R’’)-NH-(C=NH)-NR’’’H; -N=C(NR’R’’)-NH-(C=NR’’’)-NR’’’’H; -N=C(NR’R’’)-NH-(C=NH)-NR’’’R’’’’; -N=C(NR’R’’)-NH-(C=NR’’’)-NR’’’’R’’’’’;
- the groups –NH–(Rj–NH)k–H; –NH–(Rj–NH)k–R’; and
- groups derived therefrom by quaternization of one or more of the nitrogen atoms of these groups;
R’, R’’, R’’’, R’’’’ and R’’’’’ represent, independently of each other, a C1-C36 and
preferably C1-C12 alkyl group, optionally comprising one or more NH2 functions and
one or –NH- bridges;
Rj represents a C1-C6 and preferably C2-C4 alkane diyl group;
k represents an integer ranging from 1 to 20 and preferably from 2 to 12.
[107] Examples of groups Rd chosen from polyamines and polyalkylene-polyamines
that may be mentioned include: ethylenediamine, diethylenetriamine,
triethylenetetramine and tetraethylenepentamine.
[108] Very advantageously, according to this variant, the monomer mb is:
1-(phenylmethyl)-1-vinylguanidine.

[109] The copolymer may be prepared according to any known polymerization
process. The various polymerization techniques and conditions are widely described
in the literature and fall within the general knowledge of a person skilled in the art.
[110] It is understood that it would not constitute a departure from the scope of the
invention if the copolymer according to the invention were obtained from monomers
other than ma and mb, provided that the final copolymer corresponds to that of the
invention, i.e. a polymer obtained by copolymerization of at least (ma) and (mb). For
example, it would not constitute a departure from the scope of the invention if the
copolymer were obtained by copolymerization of monomers other than (ma) and (mb)
followed by post-functionalization.
[111] For example, the units derived from an alkyl (meth)acrylate monomer (ma) may
be obtained from a polymethyl (meth)acrylate fragment, by transesterification reaction
using an alcohol of chosen chain length to form the expected alkyl group.
[112] For example, the repeating unit comprising a group containing at least two
nitrogen atoms, preferably at least three nitrogen atoms, may be obtained from a
polyvinyl fragment functionalized with a precursor group, for example by reaction of a
substituted or unsubstituted guanidine with chloromethyl polystyrene divinylbenzene
as described in US 5 028 259 or by reaction of chloroformamidinium chloride with
aminomethyl polystyrene divinylbenzene as described in US 5 726 253. Such
conversion reactions are well known to those skilled in the art.
[113] The copolymer may be a statistical copolymer or a block copolymer.
[114] Preferably, the copolymer is a block copolymer.
[115] Preferably, the copolymer is a block copolymer comprising at least:
- one block A consisting of a chain of repeating units comprising an alkyl ester
function,
and
- one block B consisting of a chain of repeating units comprising at least two nitrogen
atoms, preferably at least three nitrogen atoms.
[116] Preferably, the copolymer is a block copolymer comprising at least:
- one block A consisting of a chain of structural units derived from the monomer (ma), and
- one block B consisting of a chain of structural units derived from the monomer (mb). [117] According to a particular embodiment, the block copolymer is obtained by copolymerization of at least the alkyl (meth)acrylate monomer (ma) and of at least the monomer comprising at least two nitrogen atoms, preferably at least three nitrogen atoms, (mb).
[118] The block copolymer may be obtained by block polymerization, preferably by controlled block polymerization, optionally followed by one or more post-functionalizations.

[119] According to a particular embodiment, the block copolymer described above is obtained by controlled block polymerization. The polymerization is advantageously chosen from controlled radical polymerization; for example atom transfer radical polymerization (ATRP); nitroxide-mediated radical polymerization (NMP: nitroxide-mediated polymerization); degenerative transfer processes such as degenerative iodine transfer polymerization (ITRP: iodine transfer radical polymerization) or reversible addition-fragmentation chain transfer radical polymerization (RAFT: reversible addition-fragmentation chain transfer); polymerizations derived from ATRP such as polymerizations using initiators for continuous activator regeneration (ICAR) or using activators regenerated by electron transfer (ARGET).
[120] Mention will be made, by way of example, of the publication "Macromolecular engineering by atom transfer radical polymerization" JACS, 136, 6513-6533 (2014), which describes a controlled block polymerization process for forming block copolymers.
[121] The controlled block polymerization is typically performed in a solvent, under
an inert atmosphere, at a reaction temperature generally ranging from 0 to 200°C,
preferably from 50°C to 130°C. The solvent may be chosen from polar solvents, in
particular ethers such as anisole (methoxybenzene) or tetrahydrofuran, or apolar
solvents, in particular paraffins, cycloparaffins, aromatic and alkylaromatic solvents
containing from 1 to 19 carbon atoms, for example benzene, toluene, cyclohexane,
methylcyclohexane, n-butene, n-hexane, n-heptane and the like.
[122] For atom-transfer radical polymerization (ATRP), the reaction is generally
performed under vacuum in the presence of an initiator, a ligand and a catalyst. As
examples of ligands, mention may be made of
N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA),
1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA), 2,2'-bipyridine (BPY) and tris(2-pyridylmethyl)amine (TPMA). Examples of catalysts that may be mentioned include: CuX, CuX2, with X = Cl, Br and the ruthenium-based complexes Ru2+/Ru3+. [123] The ATRP polymerization is preferably performed in a solvent chosen from polar solvents.
[124] According to the controlled block polymerization technique, it may also be envisaged to work under pressure.
[125] According to a particular embodiment, the number of equivalents of monomer ma in block A and of monomer mb in block B reacted during the polymerization reaction are identical or different and independently range from 2 to 40, preferably from 3 to 30, more preferentially from 4 to 20 and even more preferentially from 5 to 10. The term "number of equivalents" means the ratio between the amounts (in moles) of material of the monomers (ma) of block A and of the monomers (mb) of block B, used during the polymerization reaction.

[126] The number of equivalents of monomer ma in block A is advantageously greater than or equal to the number of equivalents of the monomer mb in block B. In addition, the weight-average molar mass Mw of block A or of block B is preferably less than or equal to 15 000 g.mol.-1, more preferentially less than or equal to 10 000 g.mol.-1.
[127] The block copolymer advantageously comprises at least one sequence of
blocks AB, ABA or BAB in which said blocks A and B form a chain without the
presence of an intermediate block of different chemical nature.
[128] Other blocks may optionally be present in the block copolymer described
previously provided that these blocks do not fundamentally change the nature of the
block copolymer. Block copolymers solely containing blocks A and B will,
nevertheless, be preferred.
[129] Preferably, the blocks A and B represent at least 70% by mass of the total
mass of monomers used in the polymerization reaction, preferably at least 90% by
mass, advantageously at least 95% by mass and better still at least 99% by mass.
[130] According to a particular embodiment, the block copolymer is a diblock
copolymer.
[131] According to another particular embodiment, the block copolymer is a triblock
copolymer with alternating blocks comprising two blocks A and one block B (ABA) or
comprising two blocks B and one block A (BAB).
[132] According to a particular embodiment, the block copolymer also comprises an
end chain I consisting of a saturated or unsaturated, linear, branched or cyclic C1 to
C32, preferably C4 to C24, and more preferentially C10 to C24 hydrocarbon-based chain.
[133] The term "cyclic hydrocarbon-based chain" means a hydrocarbon-based chain
of which at least part is cyclic, especially aromatic. This definition does not exclude
hydrocarbon-based chains comprising both an acyclic part and a cyclic part.
[134] The end chain I may comprise an aromatic hydrocarbon-based chain, for
example benzene-based, and/or a saturated and acyclic, linear or branched
hydrocarbon-based chain, in particular an alkyl chain.
[135] The end chain I is preferably chosen from alkyl chains, which are preferably
linear, more preferentially alkyl chains of at least 4 carbon atoms and even more
preferentially of at least 12 carbon atoms.
[136] For the ATRP polymerization, the end chain I is located in the end position of
the block copolymer. It may be introduced into the block copolymer by means of the
polymerization initiator. Thus, the end chain I may advantageously constitute at least
part of the polymerization initiator and is positioned in the polymerization initiator so
as to allow the introduction, during the first step of polymerization initiation, of the end
chain I in the end position of the block copolymer.
[137] The polymerization initiator is chosen, for example, from the free-radical

initiators used in the ATRP polymerization process. These free-radical initiators well
known to those skilled in the art are described especially in the article “Atom-transfer
radical polymerization: current status and future perspectives, Macromolecules, 45,
4015-4039, 2012".
[138] The polymerization initiator is chosen, for example, from alkyl esters of a
carboxylic acid substituted with a halide, preferably a bromine in the alpha position,
for example ethyl 2-bromopropionate, ethyl a-bromoisobutyrate, benzyl chloride or
bromide, ethyl a-bromophenylacetate and chloroethylbenzene. Thus, for example,
ethyl 2-bromopropionate may allow the introduction into the copolymer of the end
chain I in the form of a C2 alkyl chain and of benzyl bromide in the form of a benzyl
group.
[139] For the RAFT polymerization, the transfer agent may conventionally be
removed from the copolymer at the end of polymerization according to any known
process.
[140] According to a particular embodiment, the end chain I may be obtained via the
methods described in the article by Moad, G. et al., Australian Journal of Chemistry,
2012, 65, 985-1076. For example, the end chain I may be introduced by aminolysis
when a transfer agent is used. Examples that may be mentioned include transfer
agents of thiocarbonylthio, dithiocarbonate, xanthate, dithiocarbamate and
trithiocarbonate type, for example S,S-bis(a,a’-dimethyl-a’’-acetic acid)
trithiocarbonate (BDMAT) or 2-cyano-2-propyl benzodithioate.
[141] According to a particular embodiment, the block copolymer is a diblock
copolymer. The block copolymer structure may be of the IAB or IBA type,
advantageously of the IAB type. The end chain I may be connected directly to block A
or B as the structure IAB or IBA, respectively, or may be connected via a bonding
group, for example an ester, amide, amine or ether function. The bonding group then
forms a bridge between the end chain I and block A or B.
[142] According to a particular embodiment, the block copolymer may also be
functionalized at the chain end according to any known process, especially by
hydrolysis, aminolysis and/or nucleophilic substitution.
[143] The term "aminolysis" means any chemical reaction in which a molecule is split
into two parts by reaction of an ammonia molecule or an amine. A general example of
aminolysis consists in replacing a halogen of an alkyl group by reaction with an
amine, with removal of hydrogen halide. Aminolysis may be used, for example, for an
ATRP polymerization which produces a copolymer bearing a halide in the end
position or for a RAFT polymerization to remove the thio, dithio or trithio bond
introduced into the copolymer by the RAFT transfer agent.
[144] It is thus possible to introduce an end chain I’ by post-functionalization of the
block copolymer obtained by controlled block polymerization of the monomers ma and

mb described above.
[145] The end chain I’ advantageously comprises a linear, branched or cyclic C1 to C32, preferably C1 to C24 and more preferentially C1 to C10 hydrocarbon-based chain, even more preferentially an alkyl group, optionally substituted with one or more
5 groups containing at least one heteroatom chosen from N and O, preferably N.
[146] For an ATRP polymerization using a metal halide as catalyst, this functionalization may be performed, for example, by treating the copolymer IAB or IBA obtained by ATRP with a primary C1 to C32 alkylamine or a C1 to C32 alcohol under mild conditions so as not to modify the functions present on the blocks A, B
0 and I.
[147] According to a preferred embodiment, the monomer mb is chosen from 1-vinyltriazole (1-ethenyl-1,2,3-triazole), 1-vinyl-1,2,4-triazole, vinylbenzotriazole, vinyladenine, vinyltriazine, 2,4-dimethyl-6-vinyltriazine and 2-vinyl-4,6-diamino-1,3,5-triazine (CAS 3194-70-5).
5 [148] According to a preferred embodiment, the block copolymer is as described above and block B is a block B1 consisting of a chain of structural units derived from at least one monomer chosen from: 1-vinyltriazole, 1-vinyl-1,2,4-triazole, vinylbenzotriazole, vinyladenine, vinyltriazine, 2,4-dimethyl-6-vinyltriazine, 2-vinyl-4,6-diamino-1,3,5-triazine (CAS 3194-70-5).
0 [149] The block copolymer in particular comprises at least one sequence of blocks AB1, AB1A or B1AB1 in which blocks A and B1 form a chain without the presence of an intermediate block of different chemical nature.
[150] The block copolymer in particular comprises at least one sequence of blocks AB1, AB1A or B1AB1 in which blocks A and B1 form a chain without the presence of
5 an intermediate block of different chemical nature.
[151] According to a preferred particular embodiment, the block copolymer is represented by formula (IIa) or formula (IIb) below:



in which:
R and R1 are as defined above in formula (I),
x = 0 or 1,
y is an integer ranging from 2 to 40, preferably from 3 to 30, more preferentially from 4
to 20, even more preferentially from 5 to 10,
z is an integer ranging from 2 to 40, preferably from 3 to 30, more preferentially from 4
to 20, even more preferentially from 5 to 10,
R2 is chosen from linear, branched or cyclic, preferably acyclic, C6 to C34, preferably
C6 to C30, more preferentially C6 to C24 and even more preferentially C8 to C22 alkyl
groups,
R3 is chosen from hydrogen and a methyl group,
R4 is chosen from the group constituted by:
- hydrogen;
- OH;
- halogens, preferably bromine; and
- linear, branched or cyclic, saturated or unsaturated C1 to C32, preferably C1 to C24 and more preferentially C1 to C10 hydrocarbon-based chains, preferably alkyl groups, said hydrocarbon-based chains being optionally substituted with one or more groups containing at least one heteroatom chosen from N and O,
R5 and R6 are identical or different and chosen independently from the group
constituted by hydrogen and linear or branched C1 to C10 and preferably C1 to C4 alkyl
groups, even more preferentially a methyl group,
R7 is chosen from hydrocarbon-based chains, preferably cyclic or acyclic, saturated or
unsaturated, linear or branched C1 to C32, preferably C4 to C24 and more preferentially
C10 to C24 alkyl groups, and groups derived from a reversible addition-fragmentation
chain-transfer (RAFT) radical polymerization transfer agent, it being understood that if
R7 is a group derived from a transfer agent, then x = 0.
[152] Transfer agents of RAFT type are well known to those skilled in the art. A wide

diversity of RAFT-type transfer agents are available or are quite readily synthesizable. Examples that may be mentioned include transfer agents of thiocarbonylthio, dithiocarbonate, xanthate, dithiocarbamate and trithiocarbonate type, for example S,S-bis(a,a’-dimethyl-a’’-acetic acid) trithiocarbonate (BDMAT) or 2-cyano-2-propyl benzodithioate.
[153] A synthesis of block copolymer using a RAFT agent is described, for example, in the article by Zhishen Ge et al. entitled “Stimuli-Responsive Double Hydrophilic Block Copolymer Micelles with Switchable Catalytic Activity”, Macromolecules 2007, 40, 3538-3546. This article describes in particular, on pages 3540 and 3541, the synthesis of a block polymer by RAFT/MADIX polymerization. This article is cited as an example of synthesis of block copolymers and/or incorporated by reference, in particular pages 3540 and 3541. [154] Advantageously, R is chosen from the groups:
- a / b
n
m in which Ra, Rb and n are as defined above for formula (Ia), and
in which Rc, Rd and m are as defined above for formula (Ib).
[155] In formulae (IIa) and (IIb), block A corresponds to the unit repeated y times and block B to the unit repeated z times. In addition, the group R7 may be constituted of the end chain I as described above and/or the group R4 may be constituted of the end chain I’ as described above.
[156] The copolymer described above is particularly advantageous when it is used, alone or as a mixture, as detergent additive in a liquid fuel for an internal combustion engine.
[157] In particular, the block copolymer described above has noteworthy properties as detergent additive in a liquid fuel for an internal combustion engine. [158] The term "detergent additive for a liquid fuel" means an additive which is incorporated in small amount into the liquid fuel and produces an effect on the cleanliness of said engine when compared with said liquid fuel not specially supplemented with additive.
[159] The liquid fuel is advantageously derived from one or more sources chosen from the group consisting of mineral, animal, plant and synthetic sources. Crude oil will preferably be chosen as mineral source.
[160] The liquid fuel is preferably chosen from hydrocarbon-based fuels and fuels that are not essentially hydrocarbon-based, alone or as a mixture.

[161] The hydrocarbon-based fuels especially comprise middle distillates with a boiling point of between 100 and 500°C or lighter distillates with a boiling point in the gasoline range. These distillates may be chosen, for example, from the distillates obtained by direct distillation of crude hydrocarbons, vacuum distillates, hydrotreated distillates, distillates derived from the catalytic cracking and/or hydrocracking of vacuum distillates, distillates resulting from conversion processes such as ARDS (atmospheric residue desulfurization) and/or viscoreduction, and distillates derived from the upgrading of Fischer-Tropsch fractions. The hydrocarbon-based fuels are typically gasolines and gas oils (also known as diesel fuel).
[162] Gasolines in particular comprise any commercially available fuel composition for a gasoline engine. Representative examples that may be mentioned are the gasolines corresponding to standard NF EN 228. Gasolines generally have octane numbers that are high enough to avoid pinking. Typically, the fuels of gasoline type sold in Europe, in accordance with standard NF EN 228, have a motor octane number (MON) of greater than 85 and a research octane number (RON) of at least 95. Fuels of gasoline type generally have an RON of between 90 and 100 and an MON of between 80 and 90, the RON and MON being measured according to standard ASTM D 2699-86 or D 2700-86.
[163] Gas oils (diesel fuels) in particular comprise any commercially available fuel composition for diesel engines. Representative examples that may be mentioned are the gas oils corresponding to standard NF EN 590.
[164] Fuels that are not essentially hydrocarbon-based especially comprise oxygenated fuels, for example distillates resulting from BTL (biomass-to-liquid) conversion of plant and/or animal biomass, taken alone or in combination; biofuels, for example plant and/or animal oils and/or esters of plant and/or animal oils; biodiesels of animal and/or plant origin and bioethanols.
[165] The mixtures of hydrocarbon-based fuel and of fuel that is not essentially hydrocarbon-based are typically gas oils of Bx type or gasolines of Ex type. [166] The term "gas oil of Bx type for diesel engines" means a gas oil fuel which contains x% (v/v) of plant or animal ester oils (including spent cooking oils) transformed via a chemical process known as transesterification, obtained by reacting this oil with an alcohol so as to obtain fatty acid esters (FAE). With methanol and ethanol, fatty acid methyl esters (FAME) and fatty acid ethyl esters (FAEE) are obtained, respectively. The letter "B" followed by a number indicates the percentage of FAE contained in the gas oil. Thus, a B99 contains 99% of FAE and 1% of middle distillates of fossil origin (mineral source), B20 contains 20% of FAE and 80% of middle distillates of fossil origin, etc. Gas oils of B0 type which do not contain any oxygen-based compounds are thus distinguished from gas oils of Bx type which contain x% (v/v) of plant oil esters or of fatty acid esters, usually methyl esters (POME

or FAME). When the FAE is used alone in engines, the fuel is designated by the term B100.
[167] The term "gasoline of Ex type for gasoline engines" means a gasoline fuel which contains x% (v/v) of oxygen-based compounds, generally ethanol, bioethanol and/or tert-butyl ethyl ether (TBEE).
[168] The sulfur content of the liquid fuel is preferably less than or equal to 5000 ppm, preferably less than or equal to 500 ppm and more preferentially less than or equal to 50 ppm, or even less than or equal to 10 ppm and advantageously sulfur-free.
[169] The copolymer described above is used as detergent additive in the liquid fuel in a content advantageously of at least 10 ppm, preferably at least 50 ppm, more preferentially in a content ranging from 10 to 5000 ppm, even more preferentially from 10 to 1000 ppm.
[170] According to a particular embodiment, the use of a copolymer as described previously in the liquid fuel makes it possible to maintain the cleanliness of at least one of the internal parts of the internal combustion engine and/or to clean at least one of the internal parts of the internal combustion engine.
[171] The use of the copolymer in the liquid fuel makes it possible in particular to limit or prevent the formation of deposits in at least one of the internal parts of said engine ("keep-clean" effect) and/or to reduce the existing deposits in at least one of the internal parts of said engine ("clean-up" effect).
[172] Thus, the use of the copolymer in the liquid fuel makes it possible, when compared with liquid fuel that is not specially supplemented, to limit or prevent the formation of deposits in at least one of the internal parts of said engine or to reduce the existing deposits in at least one of the internal parts of said engine. [173] Advantageously, the use of the copolymer in the liquid fuel makes it possible to observe both effects simultaneously, limitation (or prevention) and reduction of deposits ("keep-clean" and "clean-up" effects).
[174] The deposits are distinguished as a function of the type of internal combustion engine and of the location of the deposits in the internal parts of said engine. [175] According to a particular embodiment, the internal combustion engine is a spark ignition engine, preferably with direct injection (DISI: direct-injection spark ignition engine). The deposits targeted are located in at least one of the internal parts of said spark ignition engine. The internal part of the spark ignition engine kept clean and/or cleaned up is advantageously chosen from the engine intake system, in particular the intake valves (IVD: intake valve deposit), the combustion chamber (CCD: combustion chamber deposit, or TCD: total chamber deposit) and the fuel injection system, in particular the injectors of an indirect injection system (PFI: port fuel injector) or the injectors of a direct injection system (DISI).

[176] According to another particular embodiment, the internal combustion engine is
a diesel engine, preferably a direct-injection diesel engine, in particular a diesel
engine with a common-rail injection system (CRDI: common-rail direct injection). The
deposits targeted are located in at least one of the internal parts of said diesel engine.
[177] Advantageously, the deposits targeted are located in the injection system of
the diesel engine, preferably located on an external part of an injector of said injection
system, for example the fuel spray tip and/or on an internal part of an injector of said
injection system (IDID: internal diesel injector deposits), for example on the surface of
an injector needle.
[178] The deposits may be constituted of coking-related deposits and/or deposits of
soap and/or lacquering type.
[179] The copolymer as described previously may advantageously be used in the
liquid fuel to reduce and/or prevent and/or avoid power loss due to the formation of
deposits in the internal parts of a direct-injection diesel engine, said power loss being
determined according to the standardized engine test method CEC F-98-08.
[180] The copolymer as described previously may advantageously be used in the
liquid fuel to reduce and/or prevent and/or avoid restriction of the fuel flow emitted by
the injector of a direct-injection diesel engine during its functioning, said flow
restriction being determined according to the standardized engine test method
CEC F-23-1-01.
[181] The use of the copolymer as described above advantageously makes it
possible to limit or prevent the formation of deposits in at least one of the internal
parts of said engine or to reduce the existing deposits in at least one of the internal
parts of said engine, on at least one type of deposit described previously.
[182] According to a particular embodiment, the use of the copolymer described
above also makes it possible to reduce the fuel consumption of an internal
combustion engine.
[183] According to another particular embodiment, the use of the copolymer
described above also makes it possible to reduce the pollutant emissions, in particular
the particle emissions of an internal combustion engine.
[184] Advantageously, the use of the copolymer makes it possible to reduce both the
fuel consumption and the pollutant emissions.
[185] The copolymer described above may be used alone, in the form of a mixture of
at least two of said copolymers or in the form of a concentrate.
[186] The copolymer may be added to the liquid fuel in a refinery and/or may be
incorporated downstream of the refinery and/or optionally as a mixture with other
additives in the form of an additive concentrate, also known by the common name
"additive package".
[187] The copolymer described above may be used as a mixture with an organic

liquid in the form of a concentrate.
[188] According to a particular embodiment, a concentrate for fuel comprises one or more copolymers as described above, as a mixture with an organic liquid. [189] The organic liquid is inert with respect to the copolymer described above and miscible in the liquid fuel described previously. The term “miscible” describes the fact that the copolymer and the organic liquid form a solution or a dispersion so as to facilitate the mixing of the copolymer in the liquid fuels according to the standard fuel supplementation processes.
[190] For the purposes of the present invention, the term "miscible" means that the organic liquid and the liquid fuel form a solution when they are mixed, in all proportions, at room temperature.
[191] The organic liquid is advantageously chosen from aromatic hydrocarbon-based solvents such as the solvent sold under the name Solvesso, alcohols, ethers and other oxygen-based compounds and paraffinic solvents such as hexane, pentane or isoparaffins, alone or as a mixture.
[192] The concentrate may advantageously comprise from 5% to 99% by mass, preferably from 10% to 80% and more preferentially from 25% to 70% of copolymer(s) as described previously.
[193] The concentrate may typically comprise from 1% to 95% by mass, preferably from 10% to 70% and more preferentially from 25% to 60% of organic liquid, the remainder corresponding to the copolymer defined previously, it being understood that the concentrate may comprise one or more copolymers as described above. [194] In general, the solubility of the copolymer in the organic liquids and the liquid fuels described previously will depend especially on the weight-average and number-average molar masses Mw and Mn, respectively, of the copolymer. The average molar masses Mw and Mn of the copolymer will be chosen so that the copolymer is soluble in the liquid fuel and/or the organic liquid of the concentrate for which it is intended. [195] The average molar masses Mw and Mn of the copolymer may also have an influence on the efficacy of this copolymer as a detergent additive. The average molar masses Mw and Mn will thus be chosen so as to optimize the effect of the copolymer, especially the detergent effect (engine cleanliness) in the liquid fuels described above.
[196] Optimizing the average molar masses Mw and Mn may be performed via routine tests accessible to those skilled in the art.
[197] According to a particular embodiment, the copolymer advantageously has a weight-average molar mass Mw ranging from 500 to 30 000 g.mol-1, preferably from 1000 to 10 000 g.mol-1, more preferentially less than or equal to 4000 g.mol-1, and/or a number-average molar mass Mn ranging from 500 to 15 000 g.mol-1, preferably from 1000 to 10 000 g.mol-1, more preferentially less than or equal to 4000 g.mol-1. The

number-average and weight-average molar masses are measured by size exclusion
chromatography (SEC). The operating conditions of SEC, especially the choice of the
solvent, will be chosen as a function of the chemical functions present in the
copolymer.
[198] According to a particular embodiment, the copolymer is used in the form of an
additive concentrate in combination with at least one other fuel additive for an internal
combustion engine other than the copolymer described previously.
[199] The additive concentrate may typically comprise one or more other additives
chosen from detergent additives other than the copolymer described above, for
example from anticorrosion agents, dispersants, de-emulsifiers, antifoams, biocides,
reodorants, proketane additives, friction modifiers, lubricant additives or oiliness
additives, combustion promoters (catalytic combustion and soot promoters), agents
for improving the cloud point, the flow point or the FLT (filterability limit temperature),
anti-sedimentation agents, anti-wear agents and conductivity modifiers.
[200] Among these additives, mention may be made in particular of:
a) proketane additives, especially (but not limitingly) chosen from alkyl nitrates, preferably 2-ethylhexyl nitrate, aryl peroxides, preferably benzyl peroxide, and alkyl peroxides, preferably tert-butyl peroxide;
b) antifoam additives, especially (but not limitingly) chosen from polysiloxanes, oxyalkylated polysiloxanes and fatty acid amides derived from plants or animal oils. Examples of such additives are given in EP 861 882, EP 663 000 and EP 736 590;
c) CFI (Cold Flow Improver) additives chosen from copolymers of ethylene and of unsaturated ester, such as ethylene/vinyl acetate (EVA), ethylene/vinyl propionate (EVP), ethylene/vinyl ethanoate (EVE), ethylene/methyl methacrylate (EMMA) and ethylene/alkyl fumarate copolymers described, for example, in US 3 048 479, US 3 627 838, US 3 790 359, US 3 961 961 and EP 261 957;
d) lubricant additives or anti-wear agents, especially (but not limitingly) chosen from the group constituted by fatty acids and ester or amide derivatives thereof, especially glyceryl monooleate, and monocyclic and polycyclic carboxylic acid derivatives. Examples of such additives are given in the following documents: EP 680 506, EP 860 494, WO 98/04656, EP 915 944, FR 2 772 783, FR 2 772 784;
e) cloud point additives, especially (but not limitingly) chosen from the group constituted by long-chain olefin/(meth)acrylic ester/maleimide terpolymers, and fumaric/maleic acid ester polymers. Examples of such additives are given in FR 2 528 051, FR 2 528 051, FR2 528 423, EP 112 195, EP 172 758, EP 271 385 and EP 291 367;
f) detergent additives, especially (but not limitingly) chosen from the group constituted by succinimides, polyetheramines and quaternary ammonium salts; for example those described in US 4 171 959 and WO 2006/135 881;

g) cold workability polyfunctional additives chosen from the group constituted by
polymers based on olefin and alkenyl nitrate as described in EP 573 490.
[201] These other additives are generally added in an amount ranging from 100 ppm
to 1000 ppm (each).
[202] The mole ratio and/or mass ratio between monomer mb and monomer ma
and/or between block A and B or B1 in the copolymer described above will be chosen
so that the block copolymer is soluble in the fuel and/or the organic liquid of the
concentrate for which it is intended. Similarly, this ratio may be optimized as a
function of the fuel and/or of the organic liquid so as to obtain the best effect on the
engine cleanliness.
[203] Optimizing the mole ratio and/or mass ratio may be performed via routine tests
accessible to those skilled in the art.
[204] The mole ratio between monomer mb and monomer ma or between blocks A
and B or B1 in the copolymer described above is advantageously from 1:10 to 10:1,
preferably from 1:2 to 2:1 and more preferentially from 1:0.5 to 0.5:2.
[205] According to a particular embodiment, a fuel composition is prepared
according to any known process by supplementing the liquid fuel described previously
with at least one copolymer as described above.
[206] According to a particular embodiment, the fuel composition comprises:
(1) a fuel as described above, and
(2) one or more copolymers as described previously.
[207] The fuel (1) is chosen in particular from hydrocarbon-based fuels and fuels that
are not essentially hydrocarbon-based described previously, alone or as a mixture.
[208] The combustion of this fuel composition comprising such a copolymer in an
internal combustion engine produces an effect on the cleanliness of the engine when
compared with the liquid fuel not specially supplemented and makes it possible in
particular to prevent or reduce the fouling of the internal parts of said engine. The
effect on the cleanliness of the engine is as described previously in the context of
using the copolymer.
[209] According to a particular embodiment, combustion of the fuel composition
comprising such a copolymer in an internal combustion engine also makes it possible
to reduce the fuel consumption and/or the pollutant emissions.
[210] The copolymer (2) is preferably incorporated in small amount into the liquid fuel
described previously, the amount of copolymer being sufficient to produce a detergent
effect as described above and thus to improve the engine cleanliness.
[211] The fuel composition advantageously comprises at least 10 ppm, preferably at
least 50 ppm, more preferentially from 10 to 5000 ppm and in particular from 10 to
1000 ppm of copolymer(s) (2).
[212] Besides the copolymer described above, the fuel composition may also

comprise one or more other additives other than the copolymer according to the invention, chosen from the other known detergent additives, for example from anticorrosion agents, dispersants, de-emulsifiers, antifoams, biocides, reodorants, proketane additives, friction modifiers, lubricant additives or oiliness additives, combustion promoters (catalytic combustion and soot promoters), agents for improving the cloud point, the flow point or the FLT, anti-sedimentation agents, anti-wear agents and/or conductivity modifiers.
[213] The various additives of the copolymer according to the invention are, for example, the fuel additives listed above.
[214] According to a particular embodiment, a process for keeping clean (keep-clean) and/or for cleaning (clean-up) at least one of the internal parts of an internal combustion engine comprises at least the following steps:
- the preparation of a fuel composition by supplementation of a fuel with one or more copolymers as described above, and
- the combustion of said fuel composition in the internal combustion engine. [215] According to a particular embodiment, the internal combustion engine is a spark ignition engine, preferably with direct injection (DISI).
[216] The internal part of the spark ignition engine that is kept clean and/or cleaned
is preferably chosen from the engine intake system, in particular the intake valves
(IVD), the combustion chamber (CCD or TCD) and the fuel injection system, in
particular the injectors of an indirect injection system (PFI) or the injectors of a direct
injection system (DISI).
[217] According to another particular embodiment, the internal combustion engine is
a diesel engine, preferably a direct-injection diesel engine, in particular a diesel
engine with a common-rail injection system (CRDI).
[218] The internal part of the diesel engine that is kept clean (keep-clean) and/or
cleaned (clean-up) is preferably the injection system of the diesel engine, preferably
an external part of an injector of said injection system, for example the fuel spray tip
and/or one of the internal parts of an injector of said injection system, for example the
surface of an injector needle.
[219] The keep-clean and/or clean-up process advantageously comprises the
successive steps of:
a) determination of the most suitable supplementation for the fuel, said supplementation corresponding to the selection of the copolymer(s) described above to be incorporated in combination, optionally, with other fuel additives as described previously and the determination of the degree of treatment necessary to achieve a given specification relative to the detergency of the fuel composition;
b) incorporation into the fuel of the selected copolymer(s) in the amount determined in step a) and, optionally, of the other fuel additives.

[220] The copolymer(s) may be incorporated into the fuel, alone or as a mixture,
successively or simultaneously.
[221] Alternatively, the copolymer(s) may be used in the form of a concentrate or of
an additive concentrate as described above.
[222] Step a) is performed according to any known process and falls within the
common practice in the field of fuel supplementation. This step involves defining at
least one representative characteristic of the detergency properties of the fuel
composition.
[223] The representative characteristic of the detergency properties of the fuel will
depend on the type of internal combustion engine, for example a diesel or gasoline
engine, the direct or indirect injection system and the location in the engine of the
deposits targeted for cleaning and/or maintaining the cleanliness.
[224] For direct-injection diesel engines, the representative characteristic of the
detergency properties of the fuel may correspond, for example, to the power loss due
to the formation of deposits in the injectors or restriction of the fuel flow emitted by the
injector during the functioning of said engine.
[225] The representative characteristic of the detergency properties may also
correspond to the appearance of lacquering-type deposits on the injector needle
(IDID).
[226] Other methods for evaluating the detergency properties of fuels have been
widely described in the literature and fall within the general knowledge of a person
skilled in the art. Mention will be made, as nonlimiting examples, of the standardized
tests or tests acknowledged by the profession or the methods described in the
following publications:
[227] For direct-injection diesel engines:
- the DW10 method, standardized engine test method CEC F-98-08, for measuring the power loss of direct-injection diesel engines
- the XUD9 method, standardized engine test method CEC F-23-1-01 Issue 5, for measuring the restriction of fuel flow emitted by the injector
- the method described by the Applicant in patent application WO 2014/029 770, pages 17 to 20, for the evaluation of lacquering deposits (IDID), this method being cited by way of example.
[228] For indirect injection gasoline engines:
- the Mercedes Benz M102E method, standardized test method CEC F-05-A-93, and
- the Mercedes Benz M111 method, standardized test method CEC F-20-A-98. These methods make it possible to measure the intake valve deposits (IVD), the tests generally being performed on a Eurosuper gasoline corresponding to standard EN228.
[229] For direct injection gasoline engines:

- the method described by the Applicant in the article "Evaluating Injector Fouling in Direct Injection Spark Ignition Engines”, Mathieu Arondel, Philippe China, Julien Gueit; Conventional and future energy for automobiles; 10th international colloquium; January 20-22, 2015 [in Stuttgart/Ostfildern; proceedings 2015]; International Colloquium Fuels/Technische Akademie Esslingen by Techn. Akad. Esslingen, Ostfildern; 2015 (ISBN 9783943563160), for evaluation of the coking deposits on the injector, this method being cited by way of example;
- the method described in US 2013/0 104 826, for evaluation of the coking deposits on the injector, this method being cited by way of example.
[230] The determination of the amount of copolymer to be added to the fuel composition to achieve the specification will typically be performed by comparison with the fuel composition not containing the copolymer according to the invention. [231] The amount of copolymer may also vary as a function of the nature and origin of the fuel, in particular as a function of the content of compounds bearing n-alkyl, isoalkyl or n-alkenyl substituents. Thus, the nature and origin of the fuel may also be a factor to be taken into consideration for step a).
[232] The process for maintaining the cleanliness (keep-clean) and/or for cleaning (clean-up) may also comprise an additional step after step b) of checking the target reached and/or of adjusting the amount of supplementation with the copolymer(s) as detergent additive.
[233] The copolymers according to the invention have noteworthy properties as detergent additive in a liquid fuel, in particular in a gas oil or gasoline fuel, in particular block copolymers.
[234] The copolymers according to the invention, in particular the block copolymers according to the invention, are particularly noteworthy especially since they are efficient as detergent additive for a wide range of liquid fuels and/or for one or more types of engine specification and/or against one or more types of deposit which become formed in the internal parts of internal combustion engines.

We Claim:
1. A method for keeping clean and/or for cleaning at least one of the internal parts of an internal combustion engine, said method comprising the introduction in said internal combustion engine of a liquid fuel comprising at least one copolymer comprising at least one repeating unit comprising an alkyl ester or alkylester function and at least one repeating unit comprising at least one hydrocarbon-based group comprising at least two nitrogen atoms
2. The method as claimed in claim 1, in which the copolymer is obtained by copolymerization of at least:
- one alkyl (meth)acrylate monomer (ma), and
- one olefinic monomer (mb) comprising at least one hydrocarbon-based group
comprising at least two nitrogen atoms.
3. The method as claimed in claim 2, in which the alkyl (meth)acrylate monomer (ma) is chosen from Ci to C34 alkyl (meth)acrylates.
4. The method as claimed in claim 2, in which the vinyl monomer (mb) comprising at least one hydrocarbon-based group comprising at least two nitrogen atoms corresponds to formula (I) below:

wherein:
R represents a hydrocarbon-based chain comprising from 1 to 24 carbon atoms,
comprising at least two nitrogen atoms, optionally one or more hydroxyl substituents
and optionally comprising one or more groups chosen from: an ether bridge -0-, an
ester bridge -COO-, a carbonyl bridge -CO-,
one or more of the nitrogen atoms may be in the form of a quaternary ammonium,
R1 represents H or CH3.
5. The method as claimed in claim 4, in which the at least two nitrogen atoms are
independently present in the group R in the form of a function chosen from: an amine
-NH2, an amine bridge -NH-, an imine bridge -N=, an amidine bridge -N=C-N-; a nitrile
function -CN, an amide bridge -CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge

-0-CO-NH-, a guanidine, alkylguanidine, aminoguanidine, biguanidine, polyamine or polyalkylene-polyamine group, a quaternary ammonium.
6. The method as claimed in claim 2, in which the monomer (nib) is represented by
formula (la):

in which:
n represents an integer chosen from 0 and 1,
Ra represents a linear, branched or cyclic C1-C12 alkyl or C2-C12 alkenyl chain,
optionally comprising one or more ether bridges -0-, an amine bridge -NH-, an imine
bridge -N=, a carbonyl bridge -CO-, an ester bridge -COO-, a carboxyl bridge -OCO-
, an amide bridge -CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge -O-CO-
NH-,
Rb represents a nitrogenous heterocycle comprising at least two nitrogen atoms,
one or more of the nitrogen atoms of Ra and/or of Rb may be in the form of a quaternary
ammonium,
R1 represents H or Chb.
7. The method as claimed in claim 6, in which: Ra represents a Ci-Cs alkyl chain optionally comprising a carbonyl bridge -CO-, and Rb is chosen from rings comprising five atoms and rings comprising six atoms, these rings comprising two or three nitrogen atoms, and two, three or four carbon atoms.
8. The method as claimed in claim 2, in which the copolymer is a block copolymer comprising at least:
- one block A consisting of a chain of structural units derived from the alkyl
(meth)acrylate monomer (ma), and
- one block B1 consisting of a chain of structural units derived from the olefinic monomer
(mt>).
9. The method as claimed in claim 1, comprising before the introduction of the liquid

fuel in the internal combustion engines:
1) the preparation of a concentrate for fuel comprising one or more copolymers as described in claim 1, as a mixture with an organic liquid, said organic liquid being inert with respect to the copolymer(s) and miscible with said fuel, and
2) the introduction of said concentrate for fuel in the liquid fuel.
The method as claimed in claim 1, comprising, before the introduction of the liquid fuel in the internal combustion engine, addition to the liquid fuel of one or more copolymers as described in claim 1.
10. The method as claimed in claim 1, in which the copolymer is added to the liquid fuel to avoid and/or reduce the formation of deposits in at least one of the internal parts of said engine and/or to reduce the existing deposits in at least one of the internal parts of said engine.
11. The method as claimed in claim 1, for reducing the fuel consumption of an internal combustion engine.
12. The method as claimed in claim 1, for limiting or reducing or avoiding or preventing the pollutant emissions of an internal combustion engine.
13. The method as claimed in claim 1, in which the internal combustion engine is a spark ignition engine.
14. The method as claimed in claim 13, for limiting or reducing or avoiding or preventing the formation of deposits in at least one internal part of a spark ignition engine chosen from the engine intake system, the combustion chamber, the fuel injection system.
15. The method as claimed in claim 1, in which the internal combustion engine is a diesel engine.
16. The method as claimed in claim 15, for limiting or reducing or avoiding or preventing the formation of deposits in the injection system of the diesel engine.
17. The method as claimed in claim 16, for limiting or reducing or avoiding or preventing the formation of deposits associated with coking and/or deposits of soap and/or lacquering type.

18. A block copolymer that may be added to the liquid fuel according to the method as claimed in claim 1, said copolymer comprising at least one repeating unit comprising an alkyl ester or alkylester function and at least one repeating unit comprising at least one hydrocarbon-based group comprising at least three nitrogen atoms.
19. The copolymer as claimed in claim 18, which is obtained by copolymerization of at least:
- one alkyl (meth)acrylate monomer (ma), and
- one olefinic monomer (nib) comprising at least one hydrocarbon-based group
comprising at least three nitrogen atoms.
20. The copolymer as claimed in Claim 19, in which the vinyl monomer (nib) comprising
at least one hydrocarbon-based group comprising at least three nitrogen atoms
corresponds to formula (I) below:
in which:
R represents a hydrocarbon-based chain comprising from 1 to 24 carbon atoms,
comprising at least three nitrogen atoms, optionally one or more hydroxyl substituents
and optionally comprising one or more groups chosen from: an ether bridge -0-, an
ester bridge -COO-, a carbonyl bridge -CO-,
one or more of the nitrogen atoms may be in the form of a quaternary ammonium,
R1 represents H or CH3.
21. The copolymer as claimed in claim 20, in which the at least three nitrogen atoms are independently present in the group R in the form of a function chosen from: an amine -NH2, an amine bridge -NH-, an imine bridge -N=, an amidine bridge -N=C-N-, a nitrile function -CN, an amide bridge -CONH-, a urea bridge -NH-CO-NH-, a carbamate bridge -0-CO-NH-, a guanidine, alkylguanidine, aminoguanidine, biguanidine, polyamine or polyalkylene-polyamine group, a quaternary ammonium.
22. The copolymer as claimed in claim 19, in which the copolymer comprises at least one sequence of blocks ABi, ABiA or B1AB1 in which said blocks A and B1 form a chain without the presence of an intermediate block of different chemical nature, said block A consisting of a chain of structural units derived from the alkyl (meth)acrylate

monomer (ma), and said block Bi consisting of a chain of structural units derived from the olefinic monomer (rrib).
23. A concentrate for fuel comprising one or more copolymers as claimed in claim 19, mixed with an organic liquid, said organic liquid being inert with respect to the copolymer(s) and miscible with said fuel.
24. A copolymer that may be added to the liquid fuel according to the method as claimed in claim 1, said copolymer being obtained by copolymerization of at least:

- one C6 to C34 alkyl (meth)acrylate monomer, or
- one vinyl alkylester monomer corresponding to the formula R'CO-0-CH=CH2 with R' a linear Ce to C34 alkyl,
and
- one olefinic monomer (nrib) comprising at least one hydrocarbon-based group
comprising at least three nitrogen atoms.
25. The copolymer as claimed in claim 24, in which the vinyl monomer (nrib) comprising
at least one hydrocarbon-based group comprising at least three nitrogen atoms
corresponds to formula (I) below:
in which:
R represents a hydrocarbon-based chain comprising from 1 to 24 carbon atoms,
comprising at least three nitrogen atoms, optionally one or more hydroxyl substituents
and optionally comprising one or more groups chosen from: an ether bridge -0-, an
ester bridge -COO-, a carbonyl bridge -CO-,
one or more of the nitrogen atoms may be in the form of a quaternary ammonium,
R1 represents H or CH3.
26. The copolymer as claimed in claim 25, in which the at least three nitrogen atoms
are independently present in the group R in the form of a function chosen from: an
amine -NH2, an amine bridge -NH-, an imine bridge -N=, an amidine bridge -N=C-N-,
a nitrile function -CN, an amide bridge -CONH-, a urea bridge -NH-CO-NH-, a
carbamate bridge -O-CO-NH-, a guanidine, alkylguanidine, aminoguanidine,

biguanidine, polyamine or polyaikylene-polyamine group, a quaternary ammonium.
27. The copolymer as claimed in one of claim 24, in which the copolymer is a block
copolymer comprising at least:
- one block A consisting of a chain of structural units derived from the alkyl
(meth)acrylate monomer (ma), and
- one block Bi consisting of a chain of structural units derived from the olefinic monomer
(nrib).
28. The copolymer as claimed in claim 27, in which the copolymer comprises at least one sequence of blocks ABi, ABiA or B1AB1 in which said blocks A and B1 form a chain without the presence of an intermediate block of different chemical nature.
29. A concentrate for fuel comprising one or more copolymers as claimed in claim 24, mixed with an organic liquid, said organic liquid being inert with respect to the copolymer(s) and miscible with said fuel.
30. A fuel composition which comprises:

(1) a fuel derived from one or more sources chosen from the group consisting of mineral, animal, plant and synthetic sources, and
(2) one or more copolymers, said copolymer comprising at least one repeating unit comprising an alkyl ester or alkylester function and at least one repeating unit comprising at least one hydrocarbon-based group comprising at least three nitrogen atoms.