Process for preparing a crosslinked polyester of glycerol and a dicarboxylic acid using a cyclic polycarboxylic anhydride, and corresponding crosslinked polyester

Abstract

The present invention relates to a process for preparing a crosslinked polyester of glycerol and a dicarboxylic acid monomer, comprising a step of crosslinking a polyester of glycerol and a dicarboxylic acid monomer with a cyclic polycarboxylic anhydride A, the cyclic polycarboxylic anhydride A comprising at least two cyclic carboxylic anhydride groups, the cyclic polycarboxylic anhydride A not comprising linear carboxylic anhydride functions. The present invention also relates to a crosslinking composition useful for implementing the process of the invention, as well as the crosslinked polyester thus obtained.

Description

Title of the invention: Process for preparing a crosslinked polyester of glycerol and a dicarboxylic acid using a cyclic polycarboxylic anhydride, and corresponding crosslinked polyester FIELD OF THE INVENTION

[0001] The present invention relates to crosslinked polyesters of glycerol and a dicarboxylic acid monomer. The present invention also relates to a process for their preparation and to a crosslinking composition useful for the preparation of said crosslinked polyesters. STATE OF THE ART

[0002] Biodegradable and / or biosourced polyesters, such as polylactic acid (PLA), polyglycolic acid (PGA) and their copolymers, such as poly(glycerol sebacate) (PGS), are now ubiquitous in the preparation of biomaterials useful both as medical biomaterials and for surface coating for various fields of application.

[0003] Conventionally, these polyesters are prepared by melt polycondensation of glycerol and a diacid, at high temperature, with fairly long reaction times. These reaction times are further extended to modify the mechanical properties of the polyester via crosslinking.

[0004] There is therefore a need for processes for preparing crosslinked polyesters with shortened crosslinking times and / or lower reaction temperatures - therefore compatible with a greater number of additives and in particular active ingredients to be encapsulated in said crosslinked polyesters - while retaining or even improving mechanical properties suitable for the intended uses. Statement of the invention

[0005] The inventors have demonstrated that the use of a crosslinking agent of the cyclic polycarboxylic anhydride type makes it possible to overcome the problems of the prior art.

[0006] Thus, the present invention relates to a process for preparing a crosslinked polyester of glycerol and a dicarboxylic acid monomer, comprising a step of crosslinking a polyester of glycerol and a dicarboxylic acid monomer with a cyclic polycarboxylic anhydride A, the cyclic polycarboxylic anhydride A comprising at least two cyclic carboxylic anhydride groups, the cyclic polycarboxylic anhydride A not comprising a linear carboxylic anhydride function.

[0007] The method of the invention thus makes it possible to achieve greatly improved elastic properties and shortened crosslinking times.

[0008] Advantageously, the cyclic carboxylic anhydride groups of the cyclic polycarboxylic anhydride A are independently chosen from ortho phthalic, succinic, maleic, homo phthalic and isatoic groups.

[0009] Advantageously, the cyclic carboxylic anhydride groups of the cyclic polycarboxylic anhydride A are joined, linked together by at least one covalent bond or carried by a spacer group L,

[0010] L representing -O- ; -S- ; -S(O)- ; -S(O)2- ; -C(O)- ; -NRnRn - with Rn and Rn independently chosen from H or a C1-C6 alkyl group, or a multivalent hydrocarbon group comprising 1 to 40 carbon atoms, cyclic or acyclic, saturated, unsaturated or aromatic, and which may contain one or more heteroatoms of O, S, Cl, Br, F, N, P or Si,

[0011] L being devoid of linear anhydride groups.

[0012] Advantageously, the cyclic polycarboxylic anhydride A comprises or is a compound of formula (I) or (II): OO (I) or 'XO A 1 J ï >,1 ko' x zt Y" -Y' 'z£ '"O (X) n PP (II) j ( ) i

[0013] in which • Li represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -NRnRn- with Rn and Rn independently selected from H or a C1-C6 alkyl group; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which from 1 to 6 methylene units are optionally replaced by an arylene group, a heteroarylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, -NRm-with Rm selected from H or a C1-C6 alkyl group, -P-, -P(O)-, -SiRaRb-with Ra and Rb independently of each other representing a -OH, C1-C6 alkyl or C1-C6 alkoxy group,

[0014] said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two C1-C6 alkyl, C1-C6 alkoxy, hydroxyl, nitro, cyano, halogen atom, C1-C6 haloalkyl group(s). • Zi is absent or represents a -CH2- (methylene) or -NH- group, • Z2 is absent or represents a -CH2- (methylene) or -NH- group, • X represents, independently of one another, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom, • n represents an integer between 0 and 3, preferably between 0 and 2, • Y represents, independently of each other, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom, • m represents an integer between 0 and 3, preferably between 0 and 2, • Ai represents: • A CC bond or a C=C bond connecting the four carbon atoms of the two carboxylic anhydride functions, • a saturated, unsaturated or aromatic carbocycle, optionally bridged, said carbocycle comprising from 4 to 30 carbon atoms, and • a saturated, unsaturated or aromatic heterocycle, optionally bridged,

[0015] said heterocycle comprising from 4 to 30 carbon atoms, and

[0016] said carbocycle or heterocycle being substituted or unsubstituted by one or more substituents chosen from a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or halogen atom.

[0017] Typically, the crosslinking step comprises the following steps: a. contacting 100 parts by weight of at least one polyester of glycerol and a dicarboxylic acid, with from 0.1 to 200 parts by weight of at least one cyclic polycarboxylic anhydride as defined herein, to obtain a mixture of crosslinking precursors, b. pressurizing the mixture obtained in the crosslinking precursor step of step a) at a target temperature Tc of between 100°C and 200°C, and for a heating time under pressure tch sufficient to obtain a crosslinked polyester, c. cooling and recovery of the crosslinked polyester.

[0018] Advantageously, step a) comprises bringing into contact 100 parts by weight of at least one glycerol polyester and a dicarboxylic acid.

[0019] Another object of the invention relates to a crosslinking composition, comprising: • 100 parts by weight of at least one polyester of glycerol and one monomer dicarboxylic acid, • from 0.1 to 200 parts by weight of at least one cyclic polycarboxylic anhydride as defined herein.

[0020] Advantageously, the dicarboxylic acid monomer has the formula [HOOC-(CH2)P -COOH], in which p is a number ranging from 1 to 30, preferably a number ranging from 1 to 10, advantageously sebacic acid (p=8).

[0021] Advantageously, the polyester of glycerol and a dicarboxylic acid monomer has a number-average molar mass Mn less than or equal to 10,000 g / mol.

[0022] Advantageously, the at least one cyclic carboxylic polyanhydride comprises a compound of formula (I) or (II): 0 O (I) or AA O' ywo  .J Ü UK CU "zf "-f xf X'Z2' (X)n (Ÿ)m 9 9 ® s To Al > : çA'zA—Z''Z£^O

[0023] in which • Li represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -NRnRn - with Rn and Rn independently selected from H or a C1-C6 alkyl group; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which from 1 to 6 methylene units are optionally replaced by an arylene group, a heteroarylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, -NRm-with Rm selected from H or a C1-C6 alkyl group, ; -P-, -P(O)-, -SiRaRb-with Ra and Rb independently of each other representing a -OH, C1-C6 alkyl or C1-C6 alkoxy group,

[0024] said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two C1-C6 alkyl, C1-C6 alkoxy, hydroxyl, nitro, cyano, halogen atom, C1-C6 haloalkyl group(s), • Zi is absent or represents a -CH2- (methylene) or -NH- group, • Z2 is absent or represents a -CH2- (methylene) or -NH- group, • X represents, independently of one another, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom, • n represents an integer between 0 and 3, preferably between 0 and 2, • Y represents, independently of each other, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom, • m represents an integer between 0 and 3, preferably between 0 and 2. • Ai represents: • A CC bond or a C=C bond connecting the four carbon atoms of the two carboxylic anhydride functions, • a saturated, unsaturated or aromatic carbocycle, optionally bridged, said carbocycle comprising from 4 to 30 carbon atoms, and • a saturated, unsaturated or aromatic heterocycle, optionally bridged,

[0025] said heterocycle comprising from 4 to 30 carbon atoms, and

[0026] said carbocycle or heterocycle being substituted or unsubstituted by one or more substituents chosen from a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or halogen atom.

[0027] Advantageously, Li represents a bond or an aliphatic chain of 1 to 6 carbon atoms, in which one or two methylene units are optionally replaced by an arylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-,

[0028] said aliphatic chain being substituted or unsubstituted by a group preferably chosen from a C1-C6 alkyl, C1-C6 alkoxy, or C1-C6 haloalkyl.

[0029] Advantageously, the at least one cyclic carboxylic polyanhydride comprises a compound of formula (III) or (IV): qo (III) < j -qq OO qp (IV)

[0030] in which represents a single or double CC bond,

[0031] L2 and L3 taken together with the carbon atoms to which they are bonded represent a saturated, unsaturated or aromatic carbocycle or heterocycle, said carbocycle or heterocycle comprising from 4 to 30 carbon atoms, and said carbocycle or heterocycle being substituted or unsubstituted by one or more substituents chosen from a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom.

[0032] Another subject of the invention relates to a polyester of glycerol and a dicarboxylic acid, crosslinked with at least one cyclic carboxylic polyanhydride as defined herein, with an elongation at break measured according to the ASTM D 1708 standard of between 20% and 300%, and advantageously a Shore A hardness measured according to the ASTM D 2240 standard at room temperature of the crosslinked polyester is between 10 and 90. The crosslinked polyester is capable of being obtained by the process of the invention. DETAILED DESCRIPTION OF THE INVENTION DEFINITIONS

[0033] For the purposes of the present invention, the term “a” or “an” means “one or more” or “at least one”.

[0034] For the purposes of the present invention, a range of values ​​designated by the expression "between a and b" represents the range of values ​​going from strictly greater than a, to strictly less than b (that is to say excluding the limits a and b), while any range of values ​​designated by the expression "from a to b" represents the range of values ​​from a to b, that is to say including the strict limits a and b.

[0035] By "approximately" is meant in the present description that the value concerned may be 10% lower or higher, in particular 5%, in particular 1%, than the indicated value.

[0036] The compounds mentioned in the description may be of fossil or bio-sourced origin. In the latter case, they may be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass. In the same way, the compounds mentioned may also come from the recycling of materials already used, that is to say they may be, partially or totally, derived from a recycling process, or obtained from raw materials themselves derived from a recycling process. This concerns in particular the monomers, that is to say in particular glycerol, the dicarboxylic acid monomer and the cyclic polycarboxylic anhydride.

[0037] Glycerol is a triol with the following formula:

[0038] In the present invention, a "cyclic polycarboxylic anhydride" means an organic compound comprising at least two cyclic carboxylic anhydride functions. Each function is chosen from a carboxylic anhydride function or a nitrogenous anhydride function. A "cyclic carboxylic anhydride function (nitrogenous or not)" is connected to two carbons of the rest of the molecule, adjacent or not, so as to form a cycle comprising a carboxylic anhydride function or a nitrogenous anhydride function. In contrast, a "linear anhydride function (nitrogenous or not)" means a divalent carboxylic anhydride function (nitrogenous or not) which is connected to two carbons of the rest of the molecule, but is not included in a cycle.

[0039] In the present invention, a “carboxylic anhydride function” corresponds to the formula -C(=O)-OC(=O)-. This function is divalent.

[0040] In the present invention, a “nitrogenous carboxylic anhydride function” corresponds to the formula -C(=O)-OC(=O)-NH. This function is divalent.

[0041] In the present invention, a “cyclic carboxylic anhydride group” means a group comprising a cyclic carboxylic anhydride function (nitrogenous or not) and further comprising from 3 to 40 carbon atoms. The cyclic anhydride group may be multivalent or monovalent. When the cyclic anhydride group is an isatoic group, then the cyclic anhydride group comprises a nitrogenous anhydride function.

[0042] When the group is further substituted, it comprises from 1 to 4, preferably from 1 to 2, substituents. The substituent(s) is (are independently) preferably a C1-C6 alkyl group, C1-C6 alkoxy, a hydroxyl, nitro, cyano, halogen atom, or a C1-C6 haloalkyl.

[0043] A "linear anhydride group" is understood within the meaning of the invention to mean a group comprising a linear carboxylic anhydride function (nitrogenous or not). Unlike a cyclic anhydride group, in a linear carboxylic anhydride group, the divalent carboxylic anhydride function (nitrogenous or not) is linked to two carbons of the rest of the molecule, but is not included in a cycle.

[0044] In the present invention, a "monovalent hydrocarbon group" means a saturated (i.e., not including any unsaturation or multiple bond), unsaturated (i.e., including at least one double bond or one triple bond, without being aromatic), or aromatic, cyclic or acyclic (linear or branched) monovalent hydrocarbon chain comprising from 1 to 40 carbon atoms. A monovalent hydrocarbon group notably covers substituted or unsubstituted C1-C40 alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl or cycloalkynyl groups. Preferably, a monovalent hydrocarbon group is a substituted or unsubstituted C1-C40 alkyl, cycloalkyl, alkenyl or cycloalkenyl group.

[0045] As used herein, a "divalent hydrocarbon group" means a saturated, unsaturated or aromatic, cyclic or acyclic (straight or branched) divalent hydrocarbon chain having from 1 to 40 carbon atoms. A divalent hydrocarbon group includes, in particular, substituted or unsubstituted, straight or branched, C1-C40 alkanediyl, alkenediyl or al-kynediyl groups. A divalent hydrocarbon group also includes substituted or unsubstituted, C1-C40 cycloalkanediyl, cycloal-kenediyl or cycloalkynediyl groups. A divalent hydrocarbon group also includes a substituted or unsubstituted divalent aromatic group. Preferably, a monovalent hydrocarbon group is a C1-C40 substituted or unsubstituted alkanediyl (linear or branched), alkenediyl (linear or branched), cycloalkanediyl, cycloalkenediyl group.

[0046] In the present invention, a "multivalent hydrocarbon group" means a hydrocarbon chain with a valence of four or more, saturated, unsaturated (i.e. comprising at least one double or optionally one triple CC bond, but not aromatic) or aromatic, cyclic or acyclic (linear or branched), comprising from 1 to 40 carbon atoms.

[0047] By "aliphatic" is meant a linear, branched and / or cyclic hydrocarbon group, whether saturated or unsaturated but not aromatic.

[0048] For the purposes of the present invention, the term “alkyl” group means a saturated, linear or branched monovalent hydrocarbon chain comprising from 1 to 40 carbon atoms, preferably comprising from 1 to 10 carbon atoms. For example, we can cite the methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl or even hexyl groups.

[0049] For the purposes of the present invention, the term “cycloalkyl” group means a saturated monovalent cyclic hydrocarbon chain comprising 3 to 40 cyclic carbon atoms. A cycloalkyl may be monocyclic, bicyclic or polycyclic. For example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cycloheptyl groups may be mentioned. An example of a polycyclic cycloalkyl is adamantyl.

[0050] For the purposes of the present invention, the term “alkenyl” group means a monovalent, linear or branched hydrocarbon chain comprising at least one double bond and comprising from 2 to 40 carbon atoms. By way of example, mention may be made of ethenyl, propenyl, allyl, butenyl, pentenyl or hexenyl groups.

[0051] For the purposes of the present invention, the term “cycloalkenyl” group means a cyclic monovalent hydrocarbon chain comprising 3 to 40 cyclic carbon atoms and at least one cyclic double bond. A cycloalkenyl may be monocyclic, bicyclic or polycyclic. For example, mention may be made of cyclobutenyl, cyclopentenyl, cyclohexenyl or cycloheptenyl groups. An example of a polycyclic cycloalkenyl is bicyclo[2.2.2]oct-7-ene.

[0052] By grouping “aie y ny le”, we mean, within the meaning of the present invention, a chain monovalent, linear or branched hydrocarbon, comprising at least one triple bond and comprising from 2 to 40 carbon atoms. Examples include ethynyl, propynyl, butynyl, pentynyl, or hexynyl groups.

[0053] For the purposes of the present invention, the term “cycloalkynyl” group means a cyclic monovalent hydrocarbon chain, comprising from 5 to 40 atoms, preferably from 7 to 40 cyclic carbon atoms and at least one cyclic triple bond. A cycloalkynyl may be monocyclic, bicyclic or polycyclic. For example, the cycloheptynyl group may be mentioned.

[0054] For the purposes of the present invention, the term "aromatic group" means an aromatic hydrocarbon group, preferably comprising from 6 to 40 carbon atoms, and comprising one or more fused rings. As an example of a monovalent aromatic group, mention may be made of a phenyl, naphthyl or pyrene group, advantageously phenyl. As an example of a divalent aromatic group, mention may be made of a phenylene, naphthylene or pyrene group, advantageously pyrene.

[0055] For the purposes of the present invention, the term “alkanediyl” group means an acyclic, linear or branched divalent hydrocarbon chain comprising from 1 to 40 carbon atoms, such as, for example, a methylene, ethanediyl, pro-panediyl, butanediyl, pentanediyl, or hexanediyl group.

[0056] For the purposes of the present invention, the term “cycloalkanedible” group means a saturated divalent cyclic hydrocarbon group, comprising from 3 to 40 cyclic carbon atoms, such as, for example, a cyclobutylene, cyclohexylene or cyclopentylene group.

[0057] For the purposes of the present invention, the term “alkenedivalent” group means an acyclic, linear or branched divalent hydrocarbon chain comprising from 2 to 40 carbon atoms and at least one double bond, such as, for example, a vinylene (ethenylene) or propenylene group.

[0058] By “cycloalkenediyl” group is meant, within the meaning of the present invention, a cyclic, linear or branched divalent hydrocarbon chain, comprising from 3 to 40 atoms, preferably from 4 to 40 or even from 5 to 40 carbon atoms and at least one double bond, such as, for example, a cyclopentenylene group.

[0059] For the purposes of the present invention, the term “alkynediyl” group means a divalent, linear or branched, acyclic hydrocarbon chain comprising from 2 to 40 carbon atoms and at least one triple bond.

[0060] For the purposes of the present invention, the term “cycloalkyndiyl” group means a cyclic monovalent hydrocarbon chain, comprising from 5 to 40, preferably from 7 to 40 or even from 8 to 40, cyclic carbon atoms and at least one cyclic triple bond. A cycloalkynyl may be monocyclic, bicyclic or polycyclic.

[0061] By “CQ alkoxy” group is meant, for the purposes of the present invention, a C1-C6 alkyl group, as defined above, linked to the rest of the molecule via an oxygen atom. By way of example, mention may be made of the methoxy, ethoxy, n-propoxy, Ao-propoxy, n-butoxy, sec-butoxy, t-butoxy, n-pentoxy, or n-hexoxy groups.

[0062] For the purposes of the present invention, the term "halogen atom" or "halogen" means fluorine, chlorine, bromine and iodine atoms, preferably fluorine and chlorine atoms.

[0063] For the purposes of the present invention, the term “CQ haloalkyl” group means a C1-C6 alkyl group, as defined above, in which one or more hydrogen atoms are replaced by a halogen atom, in particular a chlorine, bromine, iodine or fluorine atom, preferably a fluorine atom. By way of example, mention may be made of the trifluoromethyl group (-CF3).

[0064] The hydroxy group is the -OH group. The cyano group is the -CN group. The nitro group is the -NO2 group.

[0065] A "carbocycle comprising from 4 to 30 carbon atoms" means a cyclic (monovalent) hydrocarbon group comprising from 4 to 30 carbon atoms. A carbocycle may be monocyclic or polycyclic, optionally bridged (including bridged and / or joined rings). When the carbocycle is polycyclic, it comprises at least 2, advantageously 2 or 3, fused or bridged cycles. The carbocycle may be saturated (i.e. not include any unsaturation or multiple bond), unsaturated (i.e. include at least one double bond or possibly one triple bond, without being aromatic), or aromatic. When the carbocycle is aromatic, it will be referred to as an “arvle” group.

[0066] By "heterocycle comprising from 4 to 30 carbon atoms", is meant, within the meaning of the present invention, a (monovalent) cycle with 4 to 30 carbon atoms, saturated unsaturated, or aromatic, monocyclic or polycyclic optionally bridged (including bridged and / or joined cycles), of which one or more, advantageously 1 to 4, even more advantageously 1 or 2, atom(s) of the cycle is (are) a heteroatom, such as for example sulfur, nitrogen or oxygen atoms, the other cyclic atoms being carbon atoms. Examples of saturated or unsaturated heterocycles are: pyrrolidine, piperidine, piperazine, morpholine, pyrazolidinyl, imidazolidine, azepane, thia-zolidine, isothiazolidine, oxazocane, thiazepane, benzimidazolone.

[0067] An “aromatic heterocycle”, also called a (monovalent) heteroaryl group, comprises from 5 to 10 ring atoms including one or more heteroatoms, advantageously 1 to 4 and even more advantageously 1 or 2, such as for example sulfur, nitrogen or oxygen atoms, the other ring atoms being carbon atoms. Examples of heteroaryl groups are furan, thiophene, pyrrole, pyridine, imidazole, triazolyl, tetrazole, oxazole, isoxazole, thiazole, isothiazole, pyrazole, oxadiazole, thiadiazole, pyridazine, pyrimidine, pyrazine, triazine, quinole, isoquinole, quinoxal or indole.

[0068] An “arvlene group” means a divalent aromatic hydrocarbon group, preferably comprising from 6 to 10 carbon atoms, and comprising one or more fused rings, such as for example a phenyl or naphthyl group. Advantageously, it is phenylene.

[0069] A "heteroarylene group" means a divalent aromatic heterocycle, comprising from 5 to 10 ring atoms, one or more of which are heteroatoms, advantageously 1 to 4 and even more advantageously 1 or 2, such as for example sulfur, nitrogen or oxygen atoms, the other atoms of the ring being carbon atoms. Pyridinylene may be cited as an example.

[0070] According to the invention, an “orthophthalic group” means a group of formula: O, preferably of formula: p, this group ■'tüJ 1 bb being connected to the rest of the polyanhydride molecule by the “U” bond, or a group divalent of formula: xrp, this group being linked to the rest of the molecule -44-- L p b of polyanhydride by the bond on the one hand, and by the bond • on the other hand. The orthophthalic group may be substituted or unsubstituted.

[0071] In the present invention, a “succinic group” means a monovalent group of formula: p, this group being linked to the rest of the molecule of [ p O polyanhydride by the .7 / . bond, and which may be substituted or unsubstituted, or of a divalent group of formula: p, this group being linked to the rest of the J-. / ° b polyanhydride molecule by the bond on the one hand, and by the bond - on the other hand. A succinic group is distinct from an orthophthalic group, so that generally speaking, a divalent succinic group is not attached to a phenyl group.

[0072] In the present invention, a “maleic group” means a monovalent group of formula: O, this group being linked to the rest of the molecule of x .U" L. £ b polyanhydride by the U bond and which may be substituted or unsubstituted, or of a divalent group of formula: p • •, this group then being linked to the rest of the \ li P b polyanhydride molecule by the .7 bond on the one hand, and by the • bond on the other hand. A maleic group is distinct from an orthophthalic group, so that in general, a cyclic anhydride group of divalent maleic nature is not attached to a phenyl group.

[0073] In the present invention, a “homo-phthalic group” means a group O, preferably of formula: Ji ' ' xo Q, this grouping being J .4 t ■ ""O connected to the rest of the polyanhydride molecule by the bond or a group divalent of formula O, this grouping being connected to the rest of the polyanhydride molecule by the -tv bond on the one hand, and by the -A bond on the other

[0074] part. The homophthalic group may be substituted or unsubstituted. In the present invention, an "isatoic group" means a group of formula: , preferably of the formula: Or p, this group being linked to the rest of the polyanhydride molecule by the bond, or of a divalent group of formula: O, this I ! ; O

[0075]

[0076]

[0077] group being connected to the rest of the polyanhydride molecule by the bond on the one hand, and by the --bond on the other hand. The isatoic group can be substituted or unsubstituted. By "room temperature" is meant here a temperature generally between 15°C and 40°C, preferably between 20°C and 30°C, in particular around 25°C. I. Process for the preparation of a crosslinked polyester The invention relates to a process for preparing a crosslinked polyester of glycerol and a dicarboxylic acid, comprising a step of crosslinking a polyester of glycerol and a dicarboxylic acid with a cyclic polycarboxylic anhydride A, the cyclic polycarboxylic anhydride A comprising at least two cyclic carboxylic anhydride groups, the cyclic polycarboxylic anhydride A not comprising linear carboxylic anhydride functions. Cyclic polycarboxylic anhydride Preferably, the cyclic polycarboxylic anhydride comprises two functions cyclic carboxylic anhydride, that is, it is a cyclic carboxylic bis-anhydride.

[0078] In the present invention, the cyclic carboxylic anhydride groups of the cyclic polycarboxylic anhydride A are preferably independently selected from orthophthalic, succinic, maleic, homophthalic and isatoic groups.

[0079] The cyclic polycarboxylic anhydride may comprise identical or different cyclic carboxylic anhydride groups. Preferably, the cyclic carboxylic anhydride groups of the cyclic polycarboxylic anhydride are identical.

[0080] Advantageously, the cyclic carboxylic anhydride groups are independently orthophthalic, succinic or maleic groups.

[0081] Advantageously, the cyclic carboxylic anhydride groups of the cyclic polycarboxylic anhydride A are joined or linked together by at least one covalent bond or carried by a spacer group L,

[0082] L representing -O-; -S-; -S(O)-; -S(O)2-; -NRn- with Rn chosen from H or a C1-C6 alkyl group; -C(O)-; or a multivalent hydrocarbon group comprising 1 to 40 carbon atoms, cyclic or acyclic, saturated, unsaturated or aromatic, and which may contain one or more heteroatoms of O, S, Cl, Br, F, N, P or Si, and

[0083] L being devoid of linear anhydride groups.

[0084] L is chemically stable. Thus, an oxygen atom cannot be bonded to another oxygen atom and a nitrogen atom cannot be bonded to another nitrogen atom. Therefore, L is preferably free of peroxide (-OO-) or hydrazine (-NH-NH- or -NH-N(C1-C6 alkyl)- or -N(C1-C6 alkyl)-N(C1-C6 alkyl) groups. Similarly, an ester function (C(O)O) cannot be linked to another ester function. In addition, L is advantageously free of easily hydrolyzable groups. In particular, L is free of linear anhydride groups, in particular linear (divalent) carboxylic anhydride groups of formula -OC(=O)-O-. Advantageously, L is also free of ester (-OC(=O)-) or amide (-OC(=O)-NR-, with R representing H or a substituent such as a hydrocarbon chain) function.

[0085] The valence of the L group is even (since L carries cyclic carboxylic anhydride groups, which are divalent), and generally 4 or 6, preferably 4.

[0086] Advantageously, L represents a multivalent hydrocarbon group comprising 1 to 40 carbon atoms, cyclic or acyclic, saturated, unsaturated or aromatic, and which may contain one or more heteroatoms of O, S, Cl, Br, F, N, P or Si, which means that L then represents a multivalent cyclic or acyclic, saturated, unsaturated or aromatic hydrocarbon group, comprising 1 to 40 carbon atoms, in which one or more carbon atoms may be replaced by one or more heteroatoms of O, S, Cl, Br, F, N, P or Si or by a -C(O)- group.

[0087] The phosphorus (P), sulfur (S), nitrogen (N) and silicon (Si) atoms can be in oxidized form (in particular P(O), SO, SO2), and / or substituted - in particular by one or more C1-C6 alkyl groups - depending on the valence of the atom.

[0088] Particularly advantageously, L represents a cyclic or acyclic, saturated, unsaturated or aromatic multivalent hydrocarbon group, comprising 1 to 40 carbon atoms, in which one or more carbon atoms may be replaced by one or more oxygen atoms (O) or a -C(O)- or -S(O)2- group, and optionally by one or more heteroatoms of Cl, Br, F, N, P or Si.

[0089] According to particular embodiments, L represents an acyclic, saturated or unsaturated multivalent hydrocarbon group, comprising 1 to 10 carbon atoms, in which one or more carbon atoms may be replaced by one or more oxygen atoms (O) or a group -C(O)-, -S-, -S(O)-, -S(O)2-, and optionally by one or more heteroatoms of Cl, Br, F, N, P or Si.

[0090] According to other particular embodiments, L represents a cyclic, saturated, unsaturated or aromatic multivalent hydrocarbon group, comprising 3 to 40 carbon atoms, in which one or more carbon atoms may be replaced by one or more oxygen atoms (O) or a -C(O)- group, and optionally by one or more heteroatoms of S, Cl, Br, F, N, P or Si, preferably a heteroatom of Cl, Br, F. In these embodiments, the multivalent group may be monocyclic, bicyclic or polycyclic. When L is bicyclic or polycyclic, it advantageously comprises one or more attached cycles.

[0091] In particular embodiments, the cyclic polycarboxylic anhydride comprises or consists of a compound of formula (I) or preferably of formula

[0092] in which • Li represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -NRnRn - with Rn and Rn independently selected from H or a C1-C6 alkyl group; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which from 1 to 6 methylene units (preferably non-adjacent) is (are) optionally replaced by an arylene group; a heteroarylene group; -C(O)-; -O-; -S-; -S(O)-; -S(O)2-; -NRm- with Rm selected from H or a C1-C6 alkyl group; -P-; -P(O)-; -SiRaRb- with Ra and Rb independently representing a group -OH, C1-C6 alkyl or C1-C6 alkoxy,

[0093] said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two, C1-C6 alkyl groups, C1-C6 alkoxy, a hydroxyl, nitro, cyano, halogen atom, C1-C6 haloalkyl, • Zi is absent or represents a -CH2- (methylene) or -NH- group, • Z2 is absent or represents a -CH2- (methylene) or -NH- group, • X represents, independently of one another, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom, • n represents an integer between 0 and 3, preferably between 0 and 2, • Y represents, independently of each other, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom, • m represents an integer between 0 and 3, preferably between 0 and 2.

[0094] Preferably, Zi and Z2 are identical. Advantageously, Zi and Z2 both represent a bond.

[0095] Preferably, Li represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which from 1 to 6 methylene unit(s) (preferably non-adjacent) is (are) optionally replaced by an arylene group, a heteroarylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, -NRm-with Rm chosen from H or a C1-C6 alkyl group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two, C1-C6 alkyl groups, C1-C6 alkoxy, a hydroxyl, nitro, cyano, a halogen atom, a C1-C6 haloalkyl group.

[0096] Preferably, Li represents a bond; -O-; -S(O)2-; -C(O)-; or an aliphatic chain of 1 to 20 carbon atoms, in which from 1 to 4 (preferably from 1 to 2) methylene unit(s) (preferably non-adjacent) is (are) optionally replaced by an arylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-,

[0097] said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two, substituents preferably chosen from a C1-C6 alkyl, C1-C6 alkoxy, or C1-C6 haloalkyl. In particular, Li may comprise one or two divalent aromatic groups, such as phenylenes.

[0098] In particular, Li represents a radical GrG2-G3 where Gi and G3 are independently chosen from O, -S(O)2, -C(O)-; G2 is a divalent hydrocarbon group of 4 to 15 carbon atoms which may comprise one or two divalent aromatic groups, such as phenylenes, and which may be substituted by one or more, in particular one or two, groups preferably chosen from a C1-C6 alkyl, C1-C6 alkoxy, or C1-C6 haloalkyl.

[0099] Advantageously, Li represents a bond; -O-; -S(O)2-; -C(O); or an aliphatic chain of 1 to 10 carbon atoms, in particular of 1 to 6 carbon atoms, in which 1 to 2 methylene unit(s) (preferably non-adjacent) is (are) optionally replaced by an arylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-,

[0100] said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two group(s) preferably chosen from a C1-C6 alkyl, C1-C6 alkoxy, or C1-C6 haloalkyl.

[0101] Advantageously, Li represents a bond; -O-; -S(O)2-; -C(O); or an aliphatic chain of 1 to 10 carbon atoms, in particular of 1 to 6 carbon atoms, in which 1 to 2 methylene unit(s) (preferably non-adjacent) is (are) optionally replaced by an arylene group, -C(O)-, -O-, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two C1-C6 alkyl, C1-C6 alkoxy, hydroxyl, nitro, cyano, halogen atom, C1-C6 haloalkyl group, typically substituted or unsubstituted by C1-C6 alkyl, C1-C6 alkoxy, halogen atom, or C1-C6 haloalkyl group.

[0102] In particular, X may represent, independently of one another, a C1-C6 alkyl group, a hydroxyl, or a halogen atom.

[0103] Advantageously, n represents 0 or 1.

[0104] Preferably, Y may represent, independently of one another, a C1-C6 alkyl group, a hydroxyl, or a halogen atom,

[0105] Advantageously, m represents 0 or 1.

[0106] According to particular variants, n and m independently represent 0 or 1, and X and Y independently represent a C1-C6 alkyl group, a hydroxyl, or a halogen atom.

[0107] In other particular embodiments, the cyclic polycarboxylic anhydride comprises or consists of a compound of formula (II) or preferably of formula (IIa): OO (H) or j ( ) l qp (lia) 4 ( Ai ) P ob

[0108] in which

[0109] Zi is absent or represents a -CH2- (methylene) or -NH- group,

[0110] Z2 is absent or represents a -CH2- (methylene) or -NH- group,

[0111] Ai represents: • a CC bond or a C=C bond connecting the four carbon atoms of the two carboxylic anhydride functions, • a saturated, unsaturated or aromatic carbocycle, said carbocycle comprising from 4 to 30 carbon atoms, and • a saturated, unsaturated or aromatic heterocycle, said heterocycle comprising from 4 to 30 carbon atoms, and

[0112] said carbocycle or heterocycle being substituted or unsubstituted by one or more substituents, in particular a C1-C6 alkyl group, C1-C6 haloalkyl, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom.

[0113] According to certain variants, Airerepresents a polycyclic carbocycle or heterocycle with 10 to 30 members. In these variants, the polycyclic may comprise joined rings. Advantageously, Airerepresents a polycyclic aromatic carbocycle or heterocycle with 10 to 30 members, comprising two or more joined rings. It may in particular be a naphthalene group.

[0114] According to variants, Ai represents an aromatic carbocycle comprising from 6 to 10 carbon atoms, such as a phenyl or a naphthalene.

[0115] According to other variants, Ai represents a saturated carbocycle (monocyclic or bicyclic) comprising from 4 to 10, preferably from 4 to 6, carbon atoms. Preferably, it is a saturated monocyclic carbocycle comprising from 4 to 6 carbon atoms.

[0116] According to variants, the at least one of at least one cyclic carboxylic polyanhydride comprises or consists of a compound of formula (III): O (iii) îj :[ P Oh

[0117] in which represents a single or double CC bond,

[0118] L2 and L3 taken together with the carbon atoms to which they are bonded represent a saturated, unsaturated or aromatic, optionally bridged, carbocycle or heterocycle, said carbocycle or heterocycle comprising from 4 to 30 carbon atoms, and

[0119] said carbocycle or heterocycle being substituted or unsubstituted by one or more substituents chosen from a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom.

[0120] Preferably, L2 and L3 taken together with the carbon atoms to which they are bonded represent a saturated, unsaturated or aromatic carbocycle, optionally bridged,

[0121] said carbocycle comprising from 4 to 10 carbon atoms, and

[0122] said carbocycle being substituted or not substituted by one or more (in particular 1 or 2) substituents chosen from a C1-C6 alkyl group or a halogen atom.

[0123] Advantageously, L2 and L3 taken together with the carbon atoms to which they are linked represent: • a saturated or unsaturated carbocycle, optionally bridged, comprising from 4 to 8 carbon atoms, substituted or unsubstituted by one or more (in particular 1 or 2) substituents chosen from a C1-C6 alkyl group, halogen atom, or • an aromatic carbocycle of 6 to 10 carbon atoms, substituted or unsubstituted by one or more (in particular 1 or 2) substituents chosen from a C1-C6 alkyl group, halogen atom.

[0124] In particular, L2 and L3 taken together with the carbon atoms to which they are bonded may represent cyclobutyl, cyclopentyl, cyclohexyl, bicyclo[2.2.2]oct-2-enyl, or phenyl.

[0125] According to variants, the cyclic polycarboxylic anhydride comprises or consists of a compound of formula (IV): OO (IV) to Z / P [ P oh b

[0126] in which 2 represents a single or double CC bond.

[0127] According to preferred embodiments, the cyclic polycarboxylic anhydride of formula (I) is chosen from the group consisting of:

[0128] [Tableauxl] Pyromellitic acid bis-anhydride (PMDA) q P vCÏC fs 0 0 1,2,3,4-Cyclopentanetetracarboxylic acid bis-anhydride OO AA o )—ro $ 'aa 4 0 0 1,2,3,4-Cyclobutanetetracarboxylic acid bis-anhydride 0 ofm Y 0 0 ^0 0 Benzophenone-3,3 / ,4,4'-tetracarboxylic acid bis-anhydride (BTDA) "X, X. $ \ 4,4'-(4,4'-Isopropylidene-diphenoxy)phthalic acid bis-anhydride (BPADA) G I. 1' G j 1 i:} •G 4,4'-Diphthalic acid bis-anhydride (BPDA) / S 0 / / o-1" C- / G 4,4'-Oxydiphthalic acid bis-anhydride (ODPA) 0 Ci b 0 L îs P x--' b 4,4'-Hexafluoroisopropyldenediphthalic acid bis-anhydride (6FDA) 0 V, CF, K --.-. X .-a A n "ï 1 4 0 w Q 4,4'-Isopropyldenediphthalic acid bis-anhydride A 4 JO > S o 3,3',4,4'-Diphenylsulfonetetracarboxylic acid bis-anhydride (DSDA) OO, O o K. • > - S -4 o 1| T h 1 buw OO 1,4,5,8-Naphthalenetetracarboxylic acid bis-anhydride O & Ethylenetetracarboxylic acid bis-anhydride OOOO Bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid bis-anhydride P cr\ tL zb o yo o

[0129] and a mixture thereof.

[0130] Preferably, the cyclic polycarboxylic anhydride is BDTA, DPADA, BPDA and ODPA, or a mixture thereof.

[0131] The cyclic carboxylic polyanhydrides, in particular the cyclic carboxylic bis-anhydrides of the invention, are well known to those skilled in the art (see in particular US 7,425,650). They can be obtained by condensation of the corresponding tetracarboxylic acids, and some are commercially available. More specifically, for the synthesis of cyclic carboxylic polyanhydrides comprising groups:

[0132] Homophthalic: the syntheses described in US 6,797,838 can be used or adapted;

[0133] Isotaoic: we can use or adapt the syntheses described in “Ultrasonic Sonochemistry”, Volume 14, Number 5, July 2007, pages 497-501.

[0134] Polyester of glycerol and a starting dicarboxylic acid monomer (i.e. before crosslinking)

[0135] The dicarboxylic acid monomer may be aliphatic, aromatic or aliphatic / aromatic. An aliphatic / aromatic dicarboxylic acid monomer comprises an aliphatic portion and an aromatic portion. The dicarboxylic acid monomer preferably comprises from 4 to 36 carbon atoms.

[0136] According to preferred variants of the invention, the dicarboxylic acid monomer is aliphatic, in particular saturated, in particular linear or branched, preferably it is a (C3-C2o)alkanediyldicarboxylic acid, more preferably a (C8-Ci5)alkanediyldicarboxylic acid. A (Cx-Cy)alkanediyl group is a divalent, saturated, linear or branched hydrocarbon group, comprising from x to y carbon atoms.

[0137] Advantageously, the dicarboxylic acid monomer comprises or consists of a diacid of general formula [HOOC-(CH2)P-COOH] in which p is a number ranging from 1 to 30, preferably a number ranging from 5 to 10.

[0138] In particular, the dicarboxylic acid monomer may be chosen from malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexadecanedioic acid, octadecanedioic acid and a mixture of two or more of these dicarboxylic acids.

[0139] Preferably, the dicarboxylic acid monomer may be chosen from malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and a mixture of two or more of these dicarboxylic acids.

[0140] According to variants of the invention, the dicarboxylic acid monomer may be a mixture of at least two dicarboxylic acids. Preferably then, the dicarboxylic acid monomer comprises sebacic acid.

[0141] Preferably, the dicarboxylic acid monomer comprises or consists of sebacic acid.

[0142] According to preferred variants of the invention, the dicarboxylic acid monomer and glycerol are the only monomers during the polycondensation. Very preferably, the sebacic acid monomer and glycerol are the only monomers constituting the polyester of glycerol and a dicarboxylic acid monomer.

[0143] Advantageously, the glycerol / dicarboxylic acid monomer molar ratio varies from 1 / 1 to 10 / 1, in particular from 1 / 1 to 5 / 1, preferably from 1 / 1 to 2 / 1.

[0144] The polyester of glycerol and a dicarboxylic acid monomer (hereinafter called non-crosslinked polyester) advantageously has one or more of the following characteristics:

[0145] - a number average molar mass (Mn) of the non-crosslinked polyester greater than or equal to 1500 g / mol, preferably greater than or equal to 2000 g / mol;

[0146] - a number average molar mass (Mn) of the uncrosslinked polyester lower than or equal to 10,000 g / mol, preferably less than or equal to 7000 g / mol, preferably less than or equal to 5000 g / mol;

[0147] - a polydispersity Ip (Mw / Mn) of the non-crosslinked polyester less than 10, of preference less than or equal to 8;

[0148] - a residual monomer level less than or equal to 5% by weight of the weight of the uncrosslinked polyester;

[0149] - a rate of units (1,2,3-triacylglyceride) less than or equal to 20 mol%, in particular less than or equal to 15 mol%, relative to all the units of the non-crosslinked polyester;

[0150] - a molar ratio of the (1,3-diacylglyceride) unit to the (1,2-diacylglyceride) unit greater than 1 of the uncrosslinked polyester.

[0151] The polyester of glycerol and of a dicarboxylic acid monomer can be obtained in particular by implementing the processes described in EP3149067 and EP1448656.

[0152] The number-average molar mass (Mn), the mass-average molar mass (Mw), and the dispersity (also called polydispersity and noted D, which is the Mw / Mn ratio), can be measured in a known manner by size exclusion chromatography (SEC) analysis, in particular as described below.

[0153] The level of residual monomers as well as the level of units (1,2,3-triacylglyceride) is measured in a known manner by *H NMR, where appropriate combined with 2D HSQC / HMBC and 13C NMR experiments. Crosslinking

[0154] Advantageously, the crosslinking step comprises the following steps: a. contacting 100 parts by weight of at least one glycerol polyester and a dicarboxylic acid monomer, with from 0.1 to 200 parts by weight of at least one cyclic carboxylic polyanhydride as defined herein, to obtain a crosslinking precursor mixture, b. pressurizing the mixture obtained in the crosslinking precursor step of step a) to a target temperature Tc of between 100°C and 200°C, and maintaining (at temperature Tc under pressure) for a heating time under pressure tch sufficient to obtain a crosslinked polyester, c. cooling and recovery of the crosslinked polyester.

[0155] Typically, step a) comprises bringing into contact 100 parts by weight of at least one polyester of glycerol and of a dicarboxylic acid, with from 10 to 100, in particular from 15 to 90, parts by weight of at least one cyclic carboxylic polyanhydride.

[0156] Preferably, step a) of contacting is carried out in the absence of solvent, diluent or other additive.

[0157] Step a) comprises a mixture of the at least one polyester of glycerol and a dicarboxylic acid and of the at least one cyclic polycarboxylic anhydride, preferably at a temperature Ta allowing the melting of the polyester of glycerol and a dicarboxylic acid monomer, and preferably a homogeneous dispersion of the cyclic polycarboxylic anhydride. Thus, Ta is typically between 20°C and 100°C, especially between 30°C and 80°C.

[0158] In order to promote homogenization, stirring can be implemented in a known manner. Thus, step a) is typically carried out with stirring.

[0159] According to particular features of the invention, the contacting is carried out by the introduction of the cyclic polycarboxylic anhydride in solid form.

[0160] Advantageously, in step b), a platen press will be used, the plates of which have been preheated to temperature Tc.

[0161] In step b), the temperature Tc is typically between 110°C and 175°C, preferably between 120°C and 160°C.

[0162] Advantageously, the overpressure applied by the press (relative to atmospheric pressure) in heating step b) varies from 50 to 500 kPa (equivalent to 0.5 to 5 bar), in particular from 1 to 4 bar.

[0163] The heating time is determined by the time between the time the press is closed and the time it is opened.

[0164] Generally, the heating time tch is between 10 and 2000 min.

[0165] In step c), the crosslinked polyester is typically cooled and recovered at room temperature and atmospheric pressure. II. Crosslinking composition

[0166] The present invention also relates to a crosslinking composition, comprising: • 100 parts by weight of at least one polyester of glycerol and a diacid because boxylic, • from 0.1 to 200 parts by weight of at least one cyclic carboxylic polyanhydride as defined above.

[0167] Preferably, the composition comprises from 10 to 100, in particular from 15 to 90, parts by weight of at least one cyclic polycarboxylic anhydride.

[0168] The polyester of glycerol and a dicarboxylic acid, as well as cyclic polycarboxylic anhydride, may be as defined above in section 1. III. Crosslinked polyester

[0169] The present invention also relates to a polyester of glycerol and a dicarboxylic acid, crosslinked with at least one cyclic carboxylic polyanhydride as defined herein, with an elongation at break measured according to the ASTM D 1708 standard of between 20% and 300%.

[0170] The crosslinked polyester can be obtained by the process of the invention.

[0171] Advantageously, the Shore A hardness measured according to the ASTM D 2240 standard at room temperature of the crosslinked polyester is between 10 and 90. EXAMPLES

[0172] The following examples are given for illustrative purposes, but should in no way be considered as limiting the present invention. 1. Materials and methods

[0173] 1.1. Characteristics of the starting products

[0174] [Tables2] Polyester Mn (g.mol1' Mw (g.mol1) IP Poly glycerol sebacate 2656 16520 6.2

[0175] Procedure for the synthesis of the starting glycerol and sebacic acid polyester:

[0176] In a 10L double-jacketed stainless steel reactor topped with an instrumented distillation column configured in total reflux and a condenser connected to a distillate recovery pot, glycerol (1.94 kg, 1 molar equiv.) is mixed with water (0.56 kg) at 40 °C under nitrogen flow (0.5 L / min). Gentle stirring is implemented (20 rpm) for 5 min. After dissolving the glycerol, sebacic acid (4.25 kg, 1 molar equiv.) is added to the aqueous mixture in the reactor. Finally, the remaining water is added to the medium (0.56 kg). The reactor vessel is then gradually heated, following a gradual temperature rise ramp with intermediate stages, until a jacket temperature of 172°C is reached after 5 hours, corresponding to a medium temperature of 170°C, measured using an immersion probe. Stirring is increased to 80 rpm when the medium temperature exceeds 90°C.The medium is left at reflux at the start of the test. When the temperature of the vapors at the top of the distillation column reaches 98°C, and after an equilibration time of 15 min, the configuration of the column is switched to total withdrawal in order to selectively recover the water produced during the reaction.

[0177] The esterification of the medium is carried out over a total duration of 8h30, considering as the starting point the moment when the distillation begins, i.e. approximately 30 min after the introduction of the reagents. The water distilled during the test is recovered in a dedicated heat-insulated recovery pot.

[0178] Next, a vacuum installation is connected to the distillation condenser and a pressure below atmospheric pressure is applied to the reactor contents. The pressure is reduced slowly and stepwise (about 10 to 15% per step) over about 30 minutes to a target value of less than 30 mbar.

[0179] Once the pressure in the reaction vessel stabilizes at 28 mbar, the medium is left to react at 170 °C for a further 4 h. During this polycondensation step, the stirring speed is maintained at 80 rpm.

[0180] The produced PGS is transferred from the reactor vessel to a container and left cool to room temperature. The product is then transferred to a freezer for storage, where it is frozen for at least approximately 24 hours before analysis.

[0181] [Tables3] Bis Anhydride Abbreviation M (g.mol1) Benzophenone-3,3',4,4'-tetracarboxylic acid bis-anhydride BTDA 322.23 4,4'-(4,4'-Isopropylidene-diphenoxy)phthalic acid bis-anhydride BPADA 520.49 4,4'-Oxydiphthalic acid bis-anhydride ODPA 310.21 3,3',4,4'-Biphenyltetracarboxylic acid bis-anhydride BPDA 294.22

[0182] 1.2. Measurement methods Measurement of crosslinking kinetics:

[0183] The crosslinking kinetics were carried out using an MCR from the company ANTON PAAR. The measurements consist of monitoring the evolution of the elastic modulus of the compositions at 140°C with 1% deformation and a frequency of 1 Hz. The crosslinking times of the different compositions were measured so that the elastic modulus reached the value of IMPa. Shore A hardness measurement:

[0184] Shore A hardness measurements were carried out using a portable Shore durometer according to ASTM D2240 at room temperature (23°C±2°C).

[0185] The samples are prepared following the protocol described below in point 2.2. The time tch applied is the time required for the elastic modulus to reach the value of IMPa, according to the method for measuring the crosslinking kinetics.

[0186] Measurement of elongation at break (AR, expressed in %):

[0187] Mechanical tensile tests are carried out on an Instron extensometer equipped with an IkN load cell, using dumbbell specimens according to ASTM D1708 standard (thickness = 2±0.5mm) at a speed of 50 mm / min at room temperature (23°C±2°C). Macrostructure analysis: SEC RI

[0188] The SEC (Size Exclusion Chromatography) technique allows macromolecules in solution to be separated according to their size through columns filled with a porous gel. The macromolecules are separated according to their hydrodynamic volume, the largest being eluted first.

[0189] Without being an absolute method, SEC makes it possible to understand the distribution of molar masses of a polymer. From commercial standard products, the dif Different number-average (Mn) and weight-average (Mw) molar masses can be determined and the polydispersity index (Ip = Mw / Mn), also called "dispersity", calculated.

[0190] The "macrostructure" of the non-crosslinked polyesters is analyzed by size exclusion chromatography with differential refractometer detection (SEC RI), in low-weight polystyrene (PS) calibration extended with medium-weight standards. The samples are dissolved at a concentration of approximately 1g / L in THF without butylated hydroxytoluene (BHT), then stirred for two hours before being injected. The analysis temperature is 35°C, with a mobile phase flow rate of 1mL / minute on 2 Mixed E + 2 Mixed 2 columns from Agilent. 2. Results 2.1. Formulations tested

[0191] The compositions studied are presented below. The contents are expressed in % by mass or in pce (parts per cent of elastomer, i.e. of glycerol polyester and dicarboxylic acid).

[0192] The so-called "reference" mixture for each comparison is a high molecular weight poly(glycerol sebacate) polymer used alone (i.e. crosslinked in the absence of a crosslinking agent, in particular of the cyclic bis-carboxylic anhydride type). The preparation protocol used is the same as that described in point 2.2, but in the absence of cyclic polycarboxylic anhydride. The heat treatment is then 2880 min at 140°C in the platen press. • Benzophenone-33'44'-tetracarboxylic acid bisanhydride

[0193] [Tables4] Composition BTDA-1 BTDA-2 BTDA-3 PGS pce 100 100 100 BDTA pce 22.0 30 41 • 4.4'-(4 A- Isopropylidenediphenoxv) bistanh vdride d’acide phtalique)

[0194] [Tables5] Composition BPADA-1 BPADA-2 BPADA-3 PGS pce 100 100 100 BPADA pce 41 53.8 85 4A'-Oxydiphthalic acid bisanhydride

[0195] [Tableauxô] Composition ODPA-1 ODPA-2 ODPA-3 PGS pce 100 100 100 DPTDA pce 23.5 26.6 36 • Bisanh vdride of 33'44'-BiDhénvltetracarboxvliaue acid

[0196] [Tables?] Composition BPDA-1 BPDA-2 BPDA-3 PGS pce 100 100 100 BPDA pce 20.5 26.6 35

[0197] 2.2. Protocol for the preparation of crosslinked polyesters Step a)

[0198] Place a 100 mL beaker on a heating plate fitted with a PT100 probe to control the temperature.

[0199] Introduce poly(glycerol sebacate)

[0200] Heat the polymer to 50°C while mixing it using a spatula.

[0201] In another method of preparation, add the quantity of bis anhydride in the different proportions.

[0202] Mix using a spatula until a homogeneous mixture is obtained.

[0203] Cool to room temperature. Step b): crosslinking

[0204] Place the mixture in the middle of a 2mm mold between two silicone sheets 15g of the desired formulation.

[0205] Pressing on a plate at 140°C (no humidity control)

[0206] Crosslink the materials for the desired and previously determined time tch according to the crosslinking kinetics measurement method described in point 1. The time tch applied is the time required for the elastic modulus to reach the value of IMPa, according to the crosslinking kinetics measurement method.

[0207] Cool to room temperature. 2.3. Characterization of crosslinked polyesters

[0208] Properties Benzophenone-3 3'44'-tetracarboxylic bis-anhydride

[0209] [Tables8] PGS composition reference BTDA-1 BTDA-2 BTDA-3 tch at 140°C (min) 2880 150 80 30 Shore A 29 11 24 53 AR (%) 15 138 114 154

[0210] Properties 4 A '-(4 A '-Isopropylidenediphenoxy)bis(phthalic anhydride)

[0211] [T ables 9] Composition PGS reference BPADA-1 BPADA-2 BPADA-3 U at 140°C (min) 2880 150 130 100 Shore A 29 34 47 90 AR (%) 15 200 185 92 Properties 4,4'-Oxydiphthalic anhydride

[0212] [Tables10] PGS composition reference ODPA-1 ODPA-2 ODPA-3 at 140°C (min) 2880 150 100 70 Shore A 29 24 43 51 AR (%) 15 125 111 150

[0213] Properties 33' AA'-Biphenyltetracarboxylic bis-anhydride

[0214] [Tables 11] PGS composition reference BPDA-1 BPDA-2 BPDA-3 tch at 140°C (min) 2880 350 155 250 Shore A 29 25 30 67 AR (%) 15 72 119 81 3. Discussion

[0215] A systematic reduction in crosslinking time is observed for all compositions comprising polyanhydride compounds, and this is all the more marked as the concentration of polyanhydride compound is high.

[0216] The Shore A hardness is all the more important as the quantity of polyanhydride introduced is high. This clearly indicates that the degree of crosslinking is indeed linked to the concentration of polyanhydride and that it is therefore indeed the polyanhydride which is at the origin of the crosslinking. The Shore A values ​​obtained compared to that of the PGS control alone without polyanhydride are quite close or border it.

[0217] Furthermore, in comparison with the PGS control alone without polyanhydride, it is also seen that the elongations at break (AR (%)) of the compositions in accordance with the invention are improved by a factor of 10 to 20, which is very significantly better.

Claims

Claims

1. A process for preparing a crosslinked polyester of glycerol and a dicarboxylic acid monomer, comprising a step of crosslinking a polyester of glycerol and a dicarboxylic acid monomer with a cyclic polycarboxylic anhydride A, the cyclic polycarboxylic anhydride A comprising at least two cyclic carboxylic anhydride groups, the cyclic polycarboxylic anhydride A not comprising a linear carboxylic anhydride function.

2. The method of claim 1, wherein the cyclic carboxylic anhydride groups of the cyclic polycarboxylic anhydride A are independently selected from ortho phthalic, succinic, maleic, homo phthalic and isatoic groups.

3. A method according to any one of the preceding claims, wherein the cyclic carboxylic anhydride groups of the cyclic polycarboxylic anhydride A are joined, linked together by at least one covalent bond or carried by a spacer group L, L representing -O-; -S-; -S(O)-; -S(O)2-; -C(O)-; -NRnRn - with Rn and Rn independently chosen from H or a C1-C6 alkyl group, or a multivalent hydrocarbon group comprising 1 to 40 carbon atoms, cyclic or acyclic, saturated, unsaturated or aromatic, and which may contain one or more heteroatoms of O, S, Cl, Br, F, N, P or Si, L being free of linear anhydride groups.

4. A method according to any one of the preceding claims, wherein the cyclic polycarboxylic anhydride A comprises or is a compound of formula (I) or (II): OO (I) or oo (H) .1 Ji ;.J 1 J. k À À ' À ko 'zf '■"f Z2 "o cf" 'z; -- xz> (X)n in which • Li represents a bond; -O- ; -S- ; -S(O)- ; -S(O)2- ; -NRnRn' - with Rn and R„ independently selected from H or a C1-C6 alkyl group; -C(O)- ; or an aliphatic chain of 1 to 30 carbon atoms, in which from 1 to 6 methylene units is (are) optionally replaced by a arylene group, a heteroarylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, -NRm- with Rm selected from H or a C1-C6 alkyl group, -P-, -P(O)-, -SiRaRb- with Ra and Rb representing independently of each other a -OH, C1-C6 alkyl or C1-C6 alkoxy group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two C1-C6 alkyl, C1-C6 alkoxy, hydroxyl, nitro, cyano, halogen atom, C1-C6 haloalkyl group(s), • Zi is absent or represents a -CH2- (methylene) or -NH- group, • Z2 is absent or represents a -CH2- (methylene) or -NH- group, • X represents, independently of one another, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom, • n represents an integer between 0 and 3, preferably between 0 and 2, • Y represents, independently of one another, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom, • m represents an integer between 0 and 3, preferably between 0 and 2, • Ai represents: • A CC bond or a C=C bond connecting the four carbon atoms of the two carboxylic anhydride functions, • a saturated, unsaturated or aromatic carbocycle, optionally bridged, said carbocycle comprising from 4 to 30 carbon atoms, and • a saturated, unsaturated or aromatic heterocycle, optionally bridged, said heterocycle comprising from 4 to 30 carbon atoms, and said carbocycle or heterocycle being substituted or unsubstituted by a or more substituents chosen from a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or halogen atom.

5. A method according to any one of the preceding claims, wherein the crosslinking step comprises the following steps: a. contacting 100 parts by weight of at least one polyester of glycerol and a dicarboxylic acid, with from 0.1 to 200 parts by weight of at least one cyclic carboxylic polyanhydride as defined in any one of claims 1 to 4, to obtain a mixture of crosslinking precursors, b. pressurizing the mixture obtained in the crosslinking precursor step of step a) to a target temperature Tc of between 100°C and 200°C, and maintaining at the temperature Tc and under pressure for a heating time tch sufficient to obtain a crosslinked polyester, c. cooling and recovering the crosslinked polyester.

6. A method according to claim 5, wherein step a) comprises contacting 100 parts by weight of at least one polyester of glycerol and a dicarboxylic acid, with from 10 to 100 parts by weight of the at least one cyclic polycarboxylic anhydride.

7. A method according to any one of claims 5 to 6, wherein the temperature Tc is between 110°C and 175°C, preferably between 120°C and 160°C.

8. A method according to any one of claims 5 to 7, wherein the overpressure applied by the press in heating step b) is between 50 and 500 kPa.

9. A method according to any one of claims 5 to 8, wherein the heating time tch is between 10 and 2000 min.

10. Crosslinking composition, comprising: • 100 parts by weight of at least one polyester of glycerol and of a dicarboxylic acid monomer, • from 0.1 to 200 parts by weight of at least one cyclic carboxylic polyanhydride as defined in any one of claims 1 to 4.

11. Composition according to claim 10, in which the dicarboxylic acid monomer has the formula [HOOC-(CH2)P-COOH], in which p is a number ranging from 1 to 30, preferably a number ranging from 1 to 10, advantageously sebacic acid (p=8).

12. A composition according to claim 10 or 11, wherein the polyester of glycerol and a dicarboxylic acid monomer has a number-average molar mass Mn of less than or equal to 10,000 g / mol.

13. A composition according to any one of claims 10 to 12, wherein the cyclic polycarboxylic anhydride comprises a compound of formula (I) or (II): OO (I) or Q o (H) iu il J, k à à Â* X k O "2 Z2 ' 0 z 'Zp'C (X)n {Y)m in which • Li represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -NRnRn- - with Rn and R„ independently selected from H or a C1-C6 alkyl group; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which from 1 to 6 methylene units is (are) optionally replaced by an arylene group, a heteroarylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, -NRm- with Rm selected from H or a C1-C6 alkyl group;-P-, -P(O)-, -SiRaRb- with Ra and Rb independently of each other representing a group -OH, C1-C6 alkyl or C1-C6 alkoxy, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two C1-C6 alkyl, C1-C6 alkoxy, hydroxyl, nitro, cyano, halogen atom, C1-C6 haloalkyl, • Zi is absent or represents a group -CH2- (methylene) or - NH-, • Z2 is absent or represents a group -CH2- (methylene) or - NH-, • X independently of each other represents a group C1-C6 alkyl, hydroxyl, C1-C6 alkoxy, nitro, cyano,; or a halogen atom, n represents an integer between 0 and 3, preferably between 0 and 2, Y independently represents a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom, m represents an integer between 0 and 3, preferably between 0 and 2. Ai represents: • A CC bond or a C=C bond connecting the four carbon atoms of the two carboxylic anhydride functions, • a saturated, unsaturated or aromatic carbocycle, optionally bridged, said carbocycle comprising from 4 to 30 carbon atoms, and • a saturated, unsaturated or aromatic heterocycle, optionally bridged, said heterocycle comprising from 4 to 30 carbon atoms, and said carbocycle or heterocycle being substituted or unsubstituted by one or more substituents chosen from a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or halogen atom.

14. A composition according to any one of claims 10 to 13, wherein the at least one cyclic polycarboxylic anhydride comprises a compound of formula (III) or (IV): O o (ni) OO (IV) O: 4 b Q b oboo in which represents a single or double CC bond, L2 and L3 taken together with the carbon atoms to which they are bonded represent a saturated, unsaturated or aromatic carbocycle or heterocycle, said carbocycle or heterocycle having from 4 to 30 carbon atoms, and said carbocycle or heterocycle being substituted or unsubstituted by one or more substituents chosen from a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom.

15. A composition according to claim 13, wherein Li represents a bond or an aliphatic chain of 1 to 6 carbon atoms, wherein one or two methylene units are optionally replaced by an arylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, said aliphatic chain being substituted or unsubstituted by a group preferably chosen from C1-C6 alkyl, C1-C6 alkoxy, or C1-C6 haloalkyl.

16. Polyester of glycerol and a dicarboxylic acid, crosslinked with at least one cyclic carboxylic polyanhydride as defined in claim 1 to 4 or 10 to 15, with an elongation at break measured according to ASTM D 1708 of between 20% and 300%.

17. Crosslinked polyester according to claim 16, obtainable by the process according to any one of claims 1 to 9.

18. Polyester according to any one of claims 16 or 17, characterized in that the Shore A hardness measured according to the ASTM D 2240 standard at room temperature of the crosslinked polyester is between 10 and 90.