We Claim:
1. A copolymer obtained by copolymerization of at least:
- a non-polar monomer (ma) corresponding to the following formula (I)
with
u = 0 or 1,
w = 0 or 1,
E = –O– or –NH(Z)–, or –O-CO-, or –NH-CO- or -CO-NH-, with Z representing H or a
C1-C6 alkyl group, it being understood that when E = –O-CO- E is connected to the
vinyl carbon by the oxygen atom,
G represents a group chosen from a C1-C34 alkyl, an aromatic ring, an aralkyl
comprising at least one aromatic ring and at least one C1-C34 alkyl group, and
- a polar monomer (mb) chosen from those of the following formula (II):
wherein
t = 0 or 1
Q is chosen from an oxygen atom and a group -NR'- with R' being chosen from a
hydrogen atom and C1 to C12 hydrocarbon-based chains,
R is a C1 to C34 hydrocarbon-based chain substituted with at least one quaternary
ammonium group and optionally one or more hydroxyl groups.
2. The copolymer as claimed in claim 1, wherein the group E of the non-polar monomer (ma) is chosen from –O-, -NH(Z)- with Z representing H or a C1-C6 alkyl group, and –O-CO- in which E is connected to the vinyl carbon by the oxygen atom.

3. The copolymer as claimed in either of claims 1 and 2, wherein w is equal to 0.
4. The copolymer as claimed in any one of the preceding claims, wherein the group G of the non-polar monomer (ma) is chosen from a C4-C34 alkyl, an aromatic ring, an aralkyl comprising at least one aromatic ring and at least one C1-C34, preferably C4-C34 alkyl group.
5. The copolymer as claimed in any one of claims 1 to 4, wherein the group G is chosen from a C4-C34 alkyl.
6. The copolymer as claimed in any one of the preceding claims, wherein the polar monomer (mb) is represented by one of the following formulae (III) and (IV):
wherein
t and Q are as defined in formula (II),
X- is chosen from hydroxide and halide ions and organic anions,
R2 is chosen from C1 to C34 hydrocarbon-based chains, optionally substituted with at
least one hydroxyl group,
R3, R4 and R5 are identical or different and chosen independently from C1 to C18
hydrocarbon-based chains, it being understood that the alkyl groups R3, R4 and R5 may
contain one or more groups chosen from: a nitrogen atom, an oxygen atom and a
carbonyl group and that the groups R3, R4 and R5 may be connected together in pairs
to form one or more rings,
R6 and R7 are identical or different and chosen independently from C1 to C18
hydrocarbon-based chains, it being understood that the groups R6 and R7 may contain
one or more groups chosen from: a nitrogen atom, an oxygen atom and a carbonyl
group and that the groups R6 and R7 may be connected together to form a ring.
7. The copolymer as claimed in any one of the preceding claims, wherein the copolymer is chosen from block copolymers and random copolymers, preferably is a block copolymer.
8. The block copolymer as claimed in claim 7, wherein the block copolymer comprises

at least:
- a block A consisting of a chain of structural units derived from one or more non-polar monomers chosen from the non-polar monomers (ma) of formula (I), and
- a block B consisting of a chain of structural units derived from one or more polar monomers chosen from the polar monomers (mb).

9. A process for preparing a block copolymer as claimed in either one of claims 7 and 8, wherein the block B is obtained by post-functionalization of an intermediate polymer Pi resulting from the polymerization of an intermediate (meth)acrylate or (meth)acrylamide monomer (mi) of formula (VII) defined above, and wherein said post-functionalization corresponds to the reaction of said intermediate polymer Pi with a tertiary amine NR3R4R5 in which R6N=R7, in which R3, R4, R5, R6 and R7 are as defined in formulae (III) and (IV).
10. The process for preparing a block copolymer as claimed in claim 9, wherein the intermediate polymer Pi also comprises at least one block A as defined in claim 8.
11. A concentrate for fuel comprising one or more copolymers as claimed in any one of claims 1 to 8, preferably mixed with an organic liquid, said organic liquid being inert with respect to the copolymer(s) and miscible with said fuel.
12. The concentrate for fuel as claimed in claim 11, comprising at least one compound chosen from succinimides substituted with a hydrocarbon-based chain, preferably polyisobutene succinimides, said organic liquid also being inert with respect to said compound.
13. A fuel composition comprising:

(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 claimed in any one of claims 1 to 8.

14. The fuel composition as claimed in claim 13, comprising at least one compound chosen from succinimides substituted with a hydrocarbon-based chain, preferably polyisobutene succinimides.
15. The use of one or more copolymers as claimed in any one of claims 1 to 8 as detergent additive in a liquid fuel for internal combustion engines, said copolymer being used alone, as a mixture or in the form of a concentrate as defined in either of claims 11 and 12.

16. The use as claimed in claim 15, wherein the copolymer is used in the liquid fuel for:
- keeping clean and/or cleaning at least one of the internal parts of said internal combustion engine, and/or for
- reducing the fuel consumption of the internal combustion engine, and/or for
- reducing the emissions of pollutants, in particular the emissions of particles from the internal combustion engine.

17. The use as claimed in either of claims 15 and 16, as a mixture with at least one compound chosen from succinimides substituted with a hydrocarbon-based chain, preferably polyisobutene succinimides or in the form of a concentrate as claimed in claim 12 in order to improve the separation of water and fuel when the latter contains water.
18. A process for keeping clean and/or for cleaning at least one of the internal parts of an internal combustion engine, comprising at least the following steps:

- the preparation of a fuel composition by supplementation of a fuel with one or more copolymers as claimed in any one of claims 1 to 8 or a concentrate as claimed in either of claims 11 and 12, and
- combustion of said fuel composition in said internal combustion engine.