Method for preparing a crosslinked polyester of glycerol by means of a cyclic carboxylic polyanhydride in the presence of a catalyst

Abstract

The present invention relates to a method for preparing a crosslinked polyester of glycerol and of an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, the method comprising a step of crosslinking a polyester of glycerol and of an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid with a cyclic carboxylic polyanhydride A in the presence of a metal triflate (or trifluoromethylsulphonate) compound, wherein the cyclic carboxylic polyanhydride A comprises at least two cyclic carboxylic anhydride groups, wherein the cyclic carboxylic polyanhydride A does not comprise linear carboxylic anhydride functions, and wherein the metal of the metal triflate (or trifluoromethylsulphonate) compound is selected from scandium, yttrium, lanthanides, bismuth, gallium, indium, tin, thallium, aluminium, iron, copper, zinc, cadmium, titanium, zirconium, niobium, ruthenium, silver, tungsten, platinum and hafnium. The present invention also relates to a crosslinking composition that may be used for implementing the method according to the invention.

Description

[0001] Process for preparing a cross-linked glycerol polyester using a cyclic carboxylic polyanhydride in the presence of a catalyst

[0002] FIELD OF INVENTION

[0003] The present invention relates to glycerol-crosslinked polyesters. The present invention also relates to a method for their preparation and a crosslinking composition useful for preparing said crosslinked polyesters.

[0004] STATE OF THE ART

[0005] Biodegradable polyesters, such as polylactic acid (PLA), polyglycolic acid (PGA), poly(glycerol sebacate) (PGS), and their copolymers, are now ubiquitous in the preparation of biomaterials useful both as medical biomaterials and for surface coating for various fields of application.

[0006] Conventionally, these polyesters are prepared by melt polycondensation of glycerol and a diacid at high temperature, with relatively long reaction times. These reaction times are further extended to modify the polyester's mechanical properties through crosslinking.

[0007] The cross-linking of polyglycerol sebacate (PGS), described in the literature, consists of cooking at high temperature (usually 130-150°C) for a significant duration, usually 24h, 48h or 72h.

[0008] Besides impacting the productivity of thermoset PGS manufacturing, such long crosslinking times can compromise the integrity of the active pharmaceutical ingredient (API)(s) intended for incorporation into the PGS, for example, in medical applications. Exposing organic molecules to high temperatures for extended periods can thermally degrade these active ingredients, potentially rendering them ineffective at best and harmful at worst. Various approaches have been studied to reduce crosslinking times. Methods modifying the structure of the thermoset polymer have been considered to improve PGS crosslinking kinetics. For instance, functionalizing the free -OH group of PGS glycerol units with molecules that enable U-linking, physical crosslinking, etc., has been proposed.Other methods propose the use of complementary crosslinking agents. This is the case, for example, with isocyanate for synthesizing PGS-urethane described in W02020 / 041489. Other crosslinking agents that accelerate crosslinking have been studied, such as citric acid, for example in Brandon B. Risley, Xiaochu Ding, Ying Chen, Paula G. Miller, and Yadong Wang: Citrate Crosslinked Poly(Glycerol Sebacate) with Tunable Elastomeric Properties, Macromol. Biosci. 2021, 21, 2000301. There is a constant concern to find methods to access crosslinking of polyglycerol sebacate (PGS) with shorter crosslinking times and / or lower reaction temperatures - therefore compatible with a greater number of additives and in particular active ingredients to be encapsulated such as APIs - while maintaining good degradability in aqueous media suitable for specific uses as medical biomaterials.

[0009] DESCRIPTION OF THE INVENTION

[0010] The inventors have demonstrated that the use of a cyclic carboxylic polyanhydride type crosslinking agent in the presence of a metal triflate (or trifluoromethylsulfonate) compound makes it possible to overcome the problems of the prior art, the metal being chosen from scandium, yttrium, lanthanides, bismuth, gallium, indium, tin, thallium, aluminium, iron, copper, zinc, cadmium, titanium, zirconium, niobium, ruthenium, silver, tungsten, platinum and hafnium. In particular, the combined use of this crosslinking agent and metal triflate catalyst makes it possible to reduce crosslinking times and / or lower reaction temperatures when crosslinking glycerol polyesters, and to provide crosslinked glycerol polyesters that exhibit good degradability in a phosphate saline buffer solution at a temperature of 37.5°C.

[0011] Thus, the present invention relates to a method for preparing a crosslinked glycerol polyester and an aliphatic monomer selected from a dicarboxylic acid and a dicarboxylic acid diester, comprising a step of crosslinking a glycerol polyester and an aliphatic monomer selected from a dicarboxylic acid and a dicarboxylic acid diester with a cyclic polycarboxylic anhydride A in the presence of a metal triflate (or trifluoromethylsulfonate) compound, 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, and the metal of the metal triflate (or trifluoromethylsulfonate) compound being selected from scandium, yttrium, the lanthanides, bismuth, gallium, indium, tin, thallium, aluminum, iron, the copper, zinc, cadmium, titanium, zirconium, niobium, ruthenium,Silver, tungsten, platinum, and hafnium.

[0012] The process of the invention thus makes it possible to achieve shorter crosslinking times. Advantageously, the aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid has the formula [R'OOC-(CH2) P -COOR'], in which p is a number from 1 to 30, preferably from 1 to 10, and R' represents H or each R' represents, independently of each other, a linear or branched alkyl group, in the C1-C10 range, preferably in the C1-C4 range, and preferably also methyl or ethyl. Advantageously, the polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid has a number molar mass Mn less than or equal to 10,000 g / mol.

[0013] Advantageously, the crosslinked polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid is a poly(glycerol-sebacate) having a number molar mass Mn less than or equal to 10,000 g / mol.

[0014] Advantageously, the cyclic carboxylic anhydride groups of the cyclic carboxylic polyanhydride A are independently selected from ortho phthalic, succinic, maleic, homo phthalic and isatoic groups, preferably from ortho phthalic, succinic, maleic and homo phthalic groups.

[0015] 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,

[0016] The representative -O- ; -S- ; -S(O)- ; -S(O)2- ; -C(O)- ; -NR n R n - with R n and R n'independently chosen from H or an alkyl group in Ci-Ce, 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 devoid of linear anhydride groups.

[0017] Advantageously, the cyclic carboxylic polyanhydride A comprises or is a compound of formula (I) or (II): in which

[0018] • Li represents a bond; -O- ; -S- ; -S(O)- ; -S(O)2- ; -NR n R n - with R n and R n 'independently chosen from H or an alkyl group in Ci-Ce; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which 1 to 6 methylene unit(s) is / are optionally replaced by an arylene group, a heteroarylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, -NR m - with R mchosen from H or an alkyl group in Ci-Ce, -P-, -P(O)-, -SiR a Rb- with R a and Rb independently representing a -OH, Ci-Ce alkyl or Ci-Ce alkoxy group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two Ci-Ce alkyl, Ci-Ce alkoxy, hydroxyl, nitro, cyano, halogen, or Ci-Ce haloalkyl groups, • Zi is absent or represents a -CH2- (methylene) or -NH- group, preferably Z1 is absent or represents a -CH2- group,

[0019] • Z2 is absent or represents a -CH2- (methylene) or -NH- group, preferably Z2 is absent or represents a -CH2- group,

[0020] • X independently represents an alkyl group in Ci-Ce, a hydroxyl group, an alkoxy group in Ci-Ce, a nitro group, a cyano group, or a halogen atom,

[0021] • n represents an integer from 0 to 3, preferably from 0 to 2,

[0022] • Y independently represents an alkyl group in Ci-Ce, a hydroxyl group, an alkoxy group in Ci-Ce, a nitro group, a cyano group, or a halogen atom,

[0023] • m represents an integer from 0 to 3, preferably from 0 to 2,

[0024] • Ai represents: o a CC bond or a C=C bond linking the four carbon atoms of the two carboxylic anhydride functions, o a saturated, unsaturated or aromatic carbocycle, optionally bridged, said carbocycle comprising from 4 to 30 carbon atoms, or o 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 selected from a Ci-Ce alkyl group, a hydroxyl, a C1-Ce alkoxy, nitro, cyano, or halogen atom.

[0025] Preferably, Z1 is absent or represents a -CH2- group, and Z2 is absent or represents a -CH2- group.

[0026] Advantageously, the metal triflate is the scandium triflate, the bismuth triflate, or the iron triflate.

[0027] Typically, the crosslinking step includes the following steps: a) contacting 100 parts by weight of at least one polyester of glycerol and an aliphatic carboxylic diacid or diester with 0.1 to 200 parts by weight of at least one cyclic carboxylic polyanhydride as defined above, to obtain a mixture of crosslinking precursors, in the presence of 0.0001% by mass (0.1 ppm) to 1% by mass (10000 ppm) relative to the mass of polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, of a triflate metal compound, the metal being selected from scandium, yttrium, lanthanides, bismuth, gallium, indium, tin, thallium, aluminium, iron, copper, zinc, cadmium, titanium, zirconium, niobium, ruthenium, silver, tungsten, platinum and hafnium, b) pressurizing the mixture obtained in the crosslinking precursor step of step a) to a target temperature T. c between 60°C and 175°C, and for a heating time under pressure t C h sufficient to obtain a crosslinked polyester, c) cooling and recovery of the crosslinked polyester.

[0028] Advantageously, step a) includes contacting 100 parts by weight of at least one polyester with 10 to 100 parts by weight of at least one cyclic carboxylic polyanhydride.

[0029] Advantageously, step a) includes the use of 0.05 wt% (500ppm) to 1 wt% (10000ppm) relative to the mass of polyester, of a metal triflate (or trifluoromethylsulfonate) compound.

[0030] Another object of the invention relates to a crosslinking composition, comprising: o 100 parts by weight of at least one polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, o from 0.1 to 200 parts by weight of at least one cyclic polycarboxylic anhydride as defined above, o from 0.0001 wt% (0.1 ppm) to 1 wt% (10000 ppm) relative to the mass of polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, of a triflate (or trifluoromethylsulfonate) compound of metal, the metal being selected from scandium, yttrium, lanthanides, bismuth, gallium, indium, tin, thallium, aluminum, iron, copper, zinc, cadmium, titanium, zirconium, niobium, ruthenium, silver, tungsten, platinum and hafnium.

[0031] Advantageously, the aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid has the formula [R'OOC-(CH2)p-COOR'], in which p is a number from 1 to 30, preferably a number from 1 to 10, preferably p=8, and R' represents H or each R' represents, independently of each other, a linear or branched alkyl, in C1-C10, preferably in C1-C4, preferably methyl or ethyl.

[0032] Advantageously, the polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid has a number-average molar mass M n less than or equal to 10,000 g / mol.

[0033] Advantageously, at least one cyclic carboxylic polyanhydride comprises a compound of formula (I) or (II): in which

[0034] • Li represents a bond; -O- ; -S- ; -S(O)- ; -S(O)2- ; -NR n R n- with R n and R n 'independently chosen from H or an alkyl group in Ci-Ce; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which 1 to 6 methylene unit(s) is / are optionally replaced by an arylene group, a heteroarylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, -NR m - with R m chosen from H or an alkyl group in Ci-Ce, ; -P-, -P(O)-, -SiR a Rb- with R a and Rb independently representing a -OH, Ci-Ce alkyl or Ci-Ce alkoxy group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two Ci-Ce alkyl, Ci-Ce alkoxy, hydroxyl, nitro, cyano, halogen, or Ci-Ce haloalkyl groups,

[0035] • Zi is absent or represents a -CH2- (methylene) or -NH- group, preferably Z1 is absent or represents a -CH2- group,

[0036] • Z2 is absent or represents a -CH2- (methylene) or -NH- group, preferably Z2 is absent or represents a -CH2- group

[0037] • X independently represents an alkyl group in Ci-Ce, a hydroxyl group, an alkoxy group in Ci-Ce, a nitro group, a cyano group, or a halogen atom,

[0038] • n represents an integer from 0 to 3, preferably from 0 to 2,

[0039] • Y independently represents an alkyl group in Ci-Ce, a hydroxyl group, an alkoxy group in Ci-Ce, a nitro group, a cyano group, or a halogen atom,

[0040] • m represents an integer from 0 to 3, preferably from 0 to 2,

[0041] • Ai represents: o A CC bond or a C=C bond linking the four carbon atoms of the two carboxylic anhydride functions, o a saturated, unsaturated or aromatic carbocycle, optionally bridged, said carbocycle comprising from 4 to 30 carbon atoms, or o 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 selected from a Ci-Ce alkyl group, a hydroxyl, a C1-Ce alkoxy, nitro, cyano, or halogen atom.

[0042] Preferably, Z1 is absent or represents a -CH2- group, and Z2 is absent or represents a -CH2- group.

[0043] Advantageously, L1 represents an aliphatic bond or chain of 1 to 6 carbon atoms, in which one or two methylene unit(s) is / are optionally replaced by an arylene, -C(O)-, -O-, -S-, -S(O)-, -S(O)2- group, said aliphatic chain being substituted or unsubstituted by a group preferably selected from a Ci-Ce alkyl, Ci-Ce alkoxy, or Ci-Ce haloalkyl.

[0044] Advantageously, the metal triflate (or trifluoromethylsulfonate) compound is chosen from scandium triflate, bismuth triflate, and iron triflate.

[0045] DETAILED DESCRIPTION OF THE INVENTION

[0046] DEFINITIONS

[0047] For the purposes of the present invention, a range of values ​​designated by the expression "between a and b" represents the range of values ​​from greater than strictly a, to less than strictly b (i.e. excluding the bounds 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, i.e. including the strict bounds a and b.

[0048] In this description, "approximately" means that the value in question may be 10% lower or higher, in particular 5%, and especially 1% higher, than the stated value. "ppm" is commonly understood to mean "parts per million." In the context of this invention, ppm refers to the mass of polyester, glycerol, and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid.

[0049] The compounds mentioned in the description can be of fossil origin or bio-based. In the latter case, they can be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass. Similarly, the compounds mentioned can also come from the recycling of previously used materials; that is, they can be partially or totally derived from a recycling process, or obtained from raw materials themselves derived from a recycling process. This includes monomers, specifically glycerol, the aliphatic monomer selected from a dicarboxylic acid and a dicarboxylic acid diester, and cyclic carboxylic polyanhydride. Thus, advantageously, glycerol polyester is partially or totally bio-based.

[0050] OH HO J OH

[0051] Glycerol is a triol with the following formula:

[0052] In the present invention, a "cyclic polycarboxylic anhydride" means an organic compound comprising at least two cyclic carboxylic anhydride functional groups. Each functional group is selected from either a carboxylic anhydride or a nitrogen anhydride functional group. A "cyclic carboxylic anhydride (nitrogenous or non-nitrogenous) functional group" is bonded to two carbons of the rest of the molecule, whether adjacent or not, so as to form a ring comprising either a carboxylic anhydride or a nitrogen anhydride functional group. In contrast, a "linear anhydride (nitrogenous or non-nitrogenous) functional group" means a divalent carboxylic anhydride functional group (nitrogenous or non-nitrogenous) that is bonded to two carbons of the rest of the molecule but is not part of a ring.

[0053] In the present invention, a "carboxylic anhydride function" corresponds to the formula - C(=O)-OC(=O)-. This function is divalent.

[0054] In the present invention, a "nitrogenous carboxylic anhydride function" corresponds to the formula -C(=O)-OC(=O)-NH. This function is divalent.

[0055] In the present invention, a "cyclic carboxylic anhydride group" means a group comprising a cyclic carboxylic anhydride functional group (nitrogenous or non-nitrogenous) 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 isato group, then the cyclic anhydride group comprises a nitrogenous anhydride functional group. When the group is further substituted, it comprises from 1 to 4, preferably from 1 to 2, substituents. The substituent(s) is / are preferably, independently, an alkyl group in the Ci-Ce group, an alkoxy group in the Ci-Ce group, a hydroxyl group, a nitro group, a cyano group, a halogen atom, or a haloalkyl group in the Ci-Ce group.

[0056] A "linear anhydride group" is understood, for the purposes of this invention, to be a group comprising a linear carboxylic anhydride function (nitrogenous or non-nitrogenous). Unlike a cyclic anhydride group, in a linear carboxylic anhydride group, the divalent carboxylic anhydride function (nitrogenous or non-nitrogenous) is bonded to two carbons of the rest of the molecule, but is not contained within a ring.

[0057] In the present invention, a "monovalent hydrocarbon group" means a monovalent hydrocarbon chain that is saturated (i.e., containing no unsaturation or multiple bonds), unsaturated (i.e., containing at least one double or triple bond, but not aromatic), or aromatic, cyclic or acyclic (linear or branched), comprising from 1 to 40 carbon atoms. A monovalent hydrocarbon group includes, in particular, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, or cycloalkynyl groups, substituted or unsubstituted, in the C1-C40 range. Preferably, a monovalent hydrocarbon group is an alkyl, cycloalkyl, alkenyl, or cycloalkenyl group, substituted or unsubstituted, in the C1-C40 range.

[0058] As used here, a "divalent hydrocarbon group" refers to a saturated, unsaturated, or aromatic divalent hydrocarbon chain, cyclic or acyclic (linear or branched), containing from 1 to 40 carbon atoms. A divalent hydrocarbon group includes, in particular, substituted or unsubstituted, linear or branched, C1-C40 alkanediyl, alkenediyl, or alkynediyl groups. A divalent hydrocarbon group also includes substituted or unsubstituted, C1-C40 cycloalkanediyl, cycloalkenediyl, or cycloalkynediyl groups. A divalent hydrocarbon group also includes a substituted or unsubstituted divalent aromatic group. Preferably, a monovalent hydrocarbon group is an alkanediyl (linear or branched), alkenediyl (linear or branched), cycloalkanediyl, cycloalkenediyl, substituted or unsubstituted, C1-C40 group.

[0059] 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 possibly one triple C-C bond, but non-aromatic) or aromatic, cyclic or acyclic (linear or branched), comprising from 1 to 40 carbon atoms.

[0060] By "aliphatic" we mean a linear, branched and / or cyclic hydrocarbon group, whether saturated or unsaturated but non-aromatic.

[0061] For the purposes of this invention, the term "alkyl group" refers to a monovalent, saturated, linear or branched hydrocarbon chain comprising from 1 to 40 carbon atoms, preferably from 1 to 10 carbon atoms. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexyl groups.

[0062] For the purposes of this invention, a "cycloalkyl" group is defined as a monovalent cyclic saturated hydrocarbon chain comprising 3 to 40 cyclic carbon atoms. A cycloalkyl may be monocyclic, bicyclic, or polycyclic. Examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl groups. Adamantyl is an example of a polycyclic cycloalkyl.

[0063] For the purposes of this invention, an "alkenyl" group is defined as a monovalent, linear or branched hydrocarbon chain comprising at least one double bond and from 2 to 40 carbon atoms. Examples include ethenyl, propenyl, allyl, butenyl, pentenyl, and hexenyl groups.

[0064] For the purposes of this invention, a "cycloalkenyl" group is defined as a monovalent cyclic hydrocarbon chain comprising 3 to 40 cyclic carbon atoms and at least one cyclic double bond. A cycloalkenyl may be monocyclic, bicyclic, or polycyclic. Examples include cyclobutenyl, cyclopentenyl, cyclohexenyl, and cycloheptenyl. Bicyclo[2.2.2]oct-7-ene is an example of a polycyclic cycloalkenyl.

[0065] For the purposes of this invention, an "alkynyl" group is defined as a monovalent, linear or branched hydrocarbon chain comprising at least one triple bond and from 2 to 40 carbon atoms. Examples include ethynyl, propynyl, butynyl, pentynyl, and hexynyl groups.

[0066] For the purposes of this invention, a "cycloalkynyl group" is defined as a monovalent cyclic hydrocarbon chain comprising 5 to 40, preferably 7 to 40, cyclic carbon atoms and at least one triple cyclic bond. A cycloalkynyl group may be monocyclic, bicyclic, or polycyclic. The cycloheptynyl group is an example.

[0067] For the purposes of this invention, "aromatic group" means an aromatic hydrocarbon group, preferably comprising 6 to 40 carbon atoms, and including one or more fused rings. Examples of monovalent aromatic groups include phenyl, naphthyl, or pyrene, advantageously phenyl. Examples of divalent aromatic groups include phenylene, naphthylene, or pyrenylene, advantageously pyrenylene.

[0068] For the purposes of this invention, an "alkanediyl" group is defined as a linear or branched acyclic divalent hydrocarbon chain comprising 1 to 40 carbon atoms, such as, for example, a methylene, ethanediyl, propanediyl, butanediyl, pentanediyl, or hexanediyl group.

[0069] For the purposes of this invention, a "cycloalkanediyl" group is defined as a saturated divalent cyclic hydrocarbon group comprising 3 to 40 cyclic carbon atoms, such as, for example, a cyclobutylene, cyclohexylene or cyclopentylene group.

[0070] For the purposes of this invention, an "alkeniyl" group is defined as a linear or branched acyclic divalent hydrocarbon chain comprising 2 to 40 carbon atoms and at least one double bond, such as, for example, a vinylene (ethenylene) or propenylene group.

[0071] For the purposes of this invention, a "cycloalkeniyl" group is defined as a linear or branched cyclic divalent hydrocarbon chain comprising 3 to 40, preferably 4 to 40 or even 5 to 40 carbon atoms and at least one double bond, such as, for example, a cyclopentenylene group.

[0072] For the purposes of this invention, an "alkynediyl" group is defined as a divalent, linear or branched, acyclic hydrocarbon chain comprising 2 to 40 carbon atoms and at least one triple bond.

[0073] For the purposes of this invention, a "cycloalkyndiyl" group is defined as a monovalent cyclic hydrocarbon chain comprising 5 to 40, preferably 7 to 40 or even 8 to 40, cyclic carbon atoms and at least one cyclic triple bond. A cycloalkyndiyl group may be monocyclic, bicyclic, or polycyclic.

[0074] For the purposes of this invention, an "alkoxy Ci-Ce group" is defined as an alkyl Ci-Ce group, as defined above, linked to the rest of the molecule via an oxygen atom. Examples include methoxy, ethoxy, n-propoxy, / so-propoxy, n-butoxy, sec-butoxy, t-butoxy, n-pentoxy, and n-hexoxy.

[0075] For the purposes of this invention, "halogen atom" or "halogen" means fluorine, chlorine, bromine, and iodine atoms, preferably fluorine and chlorine atoms. For the purposes of this invention, "haloalkyl Ci-Ce group" means a Ci-Ce 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. An example is the trifluoromethyl (-CF3) group.

[0076] The hydroxy group is the -OH group. The cyano group is the -CN group. The nitro group is the -NO2 group.

[0077] A "carbocycle comprising 4 to 30 carbon atoms" is understood to be a cyclic (monovalent) hydrocarbon group comprising 4 to 30 carbon atoms. A carbocycle can be monocyclic or polycyclic, optionally bridged (including bridged and / or fused rings). When the carbocycle is polycyclic, it comprises at least 2, advantageously 2 or 3, fused or bridged rings. The carbocycle can be saturated (i.e., containing no unsaturation or multiple bonds), unsaturated (i.e., containing at least one double bond or possibly one triple bond, without being aromatic), or aromatic. When the carbocycle is aromatic, it is referred to as an "aryl" group.

[0078] For the purposes of this invention, a "heterocycle comprising 4 to 30 carbon atoms" means a (monovalent) ring of 4 to 30 carbon atoms, saturated, unsaturated, or aromatic, monocyclic or polycyclic, optionally bridged (including bridged and / or bonded rings), of which one or more, advantageously 1 to 4, and more advantageously 1 or 2, atoms of the ring are heteroatoms, such as, for example, sulfur, nitrogen, or oxygen atoms, the other cyclic atoms being carbon atoms. Examples of saturated or unsaturated heterocycles include: pyrrolidine, piperidine, piperazine, morpholine, pyrazolidinyl, imidazolidine, azepane, thiazolidine, isothiazolidine, oxazocane, thiazepane, and benzimidazolone.

[0079] An aromatic heterocycle, also called a heteroaryl (monovalent) group, comprises 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 sulfur, nitrogen, or oxygen atoms, the other ring atoms being carbon atoms. Examples of heteroaryl groups include furan, thiophene, pyrrole, pyridine, imidazole, triazolyl, tetrazole, oxazole, isoxazole, thiazole, isothiazole, pyrazole, oxadiazole, thiadiazole, pyridazine, pyrimidine, pyrazine, triazine, quinole, isoquinole, quinoxal, and indole.

[0080] An "arylene group" is understood to be a divalent aromatic hydrocarbon group, preferably comprising 6 to 10 carbon atoms, and including one or more attached rings, such as a phenyl or naphthyl group. Advantageously, this refers to phenylene.

[0081] A "heteroarylene group" is understood to be a divalent aromatic heterocycle, comprising 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 ring atoms being carbon atoms. Pyridinylene is an example.

[0082] According to the invention, an "orthophthalic group" is understood to be a group with the formula: preferably formula a group being linked to the rest of the polyanhydride molecule by the I bond, or a divalent group of formula: , this group being linked to the rest of the polyanhydride molecule by the

[0083] - J- liaison 1 on the one hand, and by the link 1 On the other hand, the orthophthalic group can be substituted or unsubstituted.

[0084] In the present invention, a "succinic group" is understood to be a monovalent group of formula group being linked to the rest of the polyanhydride molecule by the bond 1 and which can be substituted or unsubstituted, or of a divalent group of formula:

[0085] ° , this group being linked to the rest of the polyanhydride molecule by the bond

[0086] - - i on the one hand, and by the l bond on the other hand. A succinic group is distinct from an orthophthalic group, so that in general, a divalent succinic group is not attached to a phenyl group.

[0087] In the present invention, a "maleic group" is understood to be a monovalent group of formula a group being linked to the rest of the polyanhydride molecule by the • bond and which may be substituted or unsubstituted, or a divalent group of formula:

[0088] ° I, this group then being linked to the rest of the polyanhydride molecule by the

[0089] . X - J- bond i on one hand, and by the bond l on the other. 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.

[0090] In the present invention, a "homo-phthalic group" is understood to mean a group of formula: formula preference group being linked to the rest of the polyanhydride molecule by the divalent group with the formula: , this group being linked to the rest of the molecule of

[0091] _ _ polyanhydride by the I bond on one side, and by the l bond on the other. The homophthalic group can be substituted or unsubstituted.

[0092] In the present invention, an "isatoic grouping" means a group with the formula: Preferably, the following formula: , This a group being linked to the rest of the polyanhydride molecule by the i bond, or a divalent group of formula grouping being linked to the rest of the polyanhydride molecule by bonding 1 on the one hand, and by the link 1 On the other hand, the isatotic group can be substituted or unsubstituted.

[0093] By "room temperature," we mean a temperature generally within the range of 15°C to 40°C, preferably from 20°C to 30°C, and in particular around 25°C. Process for preparing a crosslinked polyester

[0094] The invention relates to a process for preparing a crosslinked glycerol polyester and an aliphatic carboxylic diacid or diester, comprising a step of crosslinking a glycerol polyester and a carboxylic diacid with a cyclic carboxylic polyanhydride A in the presence of a metal triflate (or trifluoromethylsulfonate) compound, the cyclic carboxylic polyanhydride A comprising at least two cyclic carboxylic anhydride groups, the cyclic carboxylic polyanhydride A not comprising a linear carboxylic anhydride function, and the metal of the metal triflate (or trifluoromethylsulfonate) compound being selected from scandium, yttrium, the lanthanides, bismuth, gallium, indium, tin, thallium, aluminum, iron, copper, zinc, cadmium, titanium, zirconium, niobium, ruthenium, silver, the tungsten, platinum and hafnium.

[0095] Polyester of the starting glycerol (i.e., before crosslinking)

[0096] The starting glycerol polyester can be a polyester of glycerol and a dicarboxylic acid monomer or a polyester of glycerol and a diester monomer of a dicarboxylic acid. The dicarboxylic acid monomer or the diester monomer of a dicarboxylic acid is aliphatic. The aliphatic dicarboxylic acid or diester monomer preferably comprises from 3 to 36 carbon atoms, and more preferably from 4 to 36 carbon atoms.

[0097] According to preferred embodiments of the invention, the carboxylic acid or diester monomer is saturated, in particular linear or branched, preferably a (C3-C2o)alkanediyldiacid carboxylic acid, more preferably a (C8-Cis)alkanediyldiacid carboxylic acid. A (Cx-Cy)alkanediyl group is a divalent, saturated, linear or branched hydrocarbon group comprising x to y carbon atoms.

[0098] According to these variants, the dicarboxylic acid monomer or the carboxylic diester monomer preferably corresponds to the general formula R'OOC-(CH2) P -COOR', in which p represents an integer from 1 to 30, preferably a number from 1 to 10, and R' represents H (hydrogen atom) or each R' represents, independently of each other, a linear or branched alkyl, in C1-C10, preferably in C1-C4, preferably also methyl or ethyl.

[0099] Thus, according to some of these variants of the invention, the dicarboxylic acid monomer comprises or consists of a diacid of general formula [HOOC-(CH2) P -COOH] in which p is a number from 1 to 30, preferably a number from 5 to 10.

[0100] Specifically, according to these variants, the dicarboxylic acid monomer may be selected 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. Preferably, the dicarboxylic acid monomer may be selected 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.

[0101] The dicarboxylic acid monomer can be a mixture of at least two dicarboxylic acids. Preferably, the dicarboxylic acid monomer comprises or consists of sebacic acid.

[0102] According to preferred embodiments of the invention, the dicarboxylic acid monomer and glycerol are the only constituent monomers of the polyester. Most preferably, sebacic acid monomer and glycerol are the only constituent monomers of the polyester, along with glycerol and a dicarboxylic acid monomer.

[0103] According to other variants, the monomer is a diester of a dicarboxylic acid corresponding to the general formula R"OOC-(CH2)n-COOR", in which n represents an integer from 1 to 30, preferably a number from 1 to 10, and each R" represents, independently of each other, a linear or branched alkyl, in C1-C10, preferably in Ci-C4, preferably also methyl or ethyl.

[0104] In particular, according to these variants of the invention, the alkyl diester monomer of dicarboxylic acid can be chosen from the alkyl diesters corresponding to malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid or a mixture of two or more of these dicarboxylic acid diesters, more preferably the dicarboxylic acid diester is chosen from the group consisting of dimethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, dimethyl pimelate, dimethyl suberate, dimethyl azelate, dimethyl sebacate, and mixtures thereof. The dicarboxylic acid diester monomer may be a mixture of at least two different dicarboxylic acid diesters.Preferably, the dicarboxylic acid diester monomer comprises or consists of an alkyl diester of sebacic acid, preferably dimethyl sebacate.

[0105] According to variations of the invention, the dicarboxylic acid diester monomer and glycerol are the only monomers. Most preferably, the alkyl diester monomer of sebacic acid, preferably dimethyl sebacate, and glycerol are the only monomers.

[0106] The glycerol polyester according to the invention can also be constituted from a mixture of an aliphatic dicarboxylic acid monomer and an aliphatic dicarboxylic acid diester monomer as defined above. According to any one of the above embodiments, the glycerol polyester according to the invention is preferably a poly(glycerol-sebacate) or PGS.

[0107] Advantageously, the molar ratio of glycerol / diacid or carboxylic diester monomer varies from 1 / 2 to 10 / 1, notably from 1 / 1 to 5 / 1, preferably from 1 / 1 to 2 / 1.

[0108] Glycerol polyester and a diacid or carboxylic diester aliphatic monomer (hereinafter referred to as non-crosslinked polyester) advantageously exhibits one or more of the following characteristics:

[0109] - an average number molar mass (Mn) of the non-crosslinked polyester greater than or equal to 800 g / mol, preferably greater than or equal to 900 g / mol, preferably greater than or equal to 1500 g / mol, preferably greater than or equal to 2000 g / mol;

[0110] - an average number molar mass (Mn) of the non-crosslinked polyester less than or equal to 10,000 g / mol, preferably less than or equal to 7,000 g / mol, preferably less than or equal to 5,000 g / mol;

[0111] - a polydispersity index Ip (Mw / Mn) of the non-crosslinked polyester of less than 10, preferably less than or equal to 8;

[0112] - a residual monomer content of less than or equal to 5% by weight of the weight of the uncrosslinked polyester;

[0113] - a rate of (1,2,3-triacylglyceride) units less than or equal to 20 mol%, in particular less than or equal to 15 mol%, relative to all units of the non-crosslinked polyester;

[0114] - a molar ratio of the unit (1,3-diacylglyceride) to the unit (1,2-diacylglyceride) greater than 1 of the non-crosslinked polyester.

[0115] The polyester of glycerol and an aliphatic dicarboxylic acid monomer can be obtained, in particular, by implementing the processes described in EP3149067 and EP1448656. The polyester of glycerol and an aliphatic diester carboxylic acid monomer can be obtained, in particular, by implementing the processes described in FR2315383.

[0116] The number-average molar mass (Mn), the mass-average molar mass (Mw), and the polydispersity index (also called polydispersity and denoted D, which is the ratio Mw / Mn), can be measured in a known manner by size-exclusion chromatography (SEC) analysis, notably as described below.

[0117] The residual monomer content and the (1,2,3-triacylglyceride) unit content are measured using a known method by NMR. 1 H, possibly combined with 2D HSQC / HMBC and NMR experiments 13 C. Cyclic carboxylic polyanhydride

[0118] Preferably, the cyclic carboxylic polyanhydride comprises two cyclic carboxylic anhydride functions, that is to say, it is a cyclic bis-carboxylic anhydride.

[0119] Advantageously, it acts on non-nitrogenous cyclic carboxylic anhydride functions.

[0120] In the present invention, the cyclic carboxylic anhydride groups of the cyclic carboxylic polyanhydride A are preferably independently selected from orthophthalic, succinic, maleic, homophthalic and isatoic groups, preferably from orthophthalic, succinic, maleic and homophthalic groups.

[0121] The cyclic carboxylic polyanhydride may comprise identical or different cyclic carboxylic anhydride groups. Preferably, the cyclic carboxylic anhydride groups of the cyclic carboxylic polyanhydride are identical.

[0122] Advantageously, the cyclic carboxylic anhydride groups are independent of the orthophthalic, succinic, or maleic groups.

[0123] Advantageously, the cyclic carboxylic anhydride groups of the cyclic polycarboxylic anhydride A are joined or linked to each other by at least one covalent bond or carried by a spacer group L,

[0124] The representative -O- ; -S- ; -S(O)- ; -S(O)2- ; -NR n - with R n chosen from H or an alkyl group in Ci-Ce; -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

[0125] L being devoid of linear anhydride groups.

[0126] 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 devoid of peroxide (-OO-) or hydrazine (-NH-NH- or -NH-N(alkyl Ci-Ce)- or -N(alkyl Ci-Ce)-N(alkyl Ci-Ce) groups). Similarly, an ester (C(O)O) function cannot be bonded to another ester function. Furthermore, L is advantageously devoid of readily hydrolyzable groups. In particular, L is devoid of linear anhydride groups, especially linear (divalent) carboxylic anhydride groups of the formula -OC(=O)-O-. Advantageously, L is also devoid of ester (-OC(=O)-) or amide (-OC(=O)-NR-) functions, with R representing H or a substituent such as a hydrocarbon chain.

[0127] The valence of the L group is even (since L carries cyclic carboxylic anhydride groups, which are divalent), and generally of 4 or 6, preferably of 4.

[0128] Advantageously, L represents a multivalent hydrocarbon group comprising 1 to 40 carbon atoms, cyclic or acyclic, saturated, unsaturated or aromatic, and capable of containing one or more heteroatoms of O, S, Cl, Br, F, N, P or Si, which means that L then 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 can be replaced by one or more heteroatoms of O, S, Cl, Br, F, N, P or Si or by a -C(O)- group.

[0129] Phosphorus (P), sulfur (S), nitrogen (N) and silicon (Si) atoms can be in oxidized form (notably P(O), SO, SO2), and / or substituted - notably by an alkyl group in Ci-Ce - depending on the valence of the atom.

[0130] Most 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 can be replaced by one or more oxygen (O) atoms or a -C(O)- or -S(O)2- group, and optionally by one or more heteroatoms of Cl, Br, F, N, P or Si.

[0131] According to particular embodiments, L represents a multivalent acyclic hydrocarbon group, saturated or unsaturated, comprising 1 to 10 carbon atoms, in which one or more carbon atoms can be replaced by one or more oxygen (O) atoms or a -C(O)-, -S-, -S(O)-, -S(O)2- group, and optionally by one or more heteroatoms of Cl, Br, F, N, P or Si.

[0132] In other specific embodiments, L represents a saturated, unsaturated, or aromatic cyclic multivalent hydrocarbon group comprising 3 to 40 carbon atoms, wherein 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, or 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 fused rings.

[0133] In particular embodiments, the cyclic carboxylic polyanhydride comprises or is made up of a compound of formula (I) or preferably of formula (la): in which

[0134] • L1 represents a bond; -O- ; -S- ; -S(O)- ; -S(O)2- ; -NR n R n - with Rn and R n 'independently chosen from H or an alkyl group in Ci-Ce; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which 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-; -NR m - with R m chosen from H or an alkyl group in Ci-Ce; -P-; -P(O)-; -SiR a Rb- with R a and Rb independently representing a -OH, alkyl in Ci-Ce or alkoxy in Ci-Ce group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two, alkyl in Ci-Ce, alkoxy in Ci-Ce group, a hydroxyl, nitro, cyano, halogen atom, haloalkyl in Ci-Ce,

[0135] • Zi is absent or represents a -CH2- (methylene) or -NH- group, preferably Z1 is absent or represents a -CH2- group,

[0136] • Z2 is absent or represents a -CH2- (methylene) or -NH- group, preferably Z2 is absent or represents a -CH2- group,

[0137] • X independently represents an alkyl group in Ci-Ce, a hydroxyl group, an alkoxy group in Ci-Ce, a nitro group, a cyano group, or a halogen atom,

[0138] • n represents an integer from 0 to 3, preferably from 0 to 2,

[0139] • Y independently represents an alkyl group in Ci-Ce, a hydroxyl group, an alkoxy group in Ci-Ce, a nitro group, a cyano group, or a halogen atom,

[0140] • m represents an integer from 0 to 3, preferably from 0 to 2.

[0141] Advantageously, Z1 is absent or represents a -CH2- group, and Z2 is absent or represents a -CH2- group. Preferably, Z1 and Z2 are identical. Advantageously, Z1 and Z2 both represent a bond (which is equivalent to saying that Z1 and Z2 are both absent).

[0142] Preferably, L1 represents a bond of -O-, -S-, -S(O)-, -S(O)2-, -C(O)-, or an aliphatic chain of 1 to 30 carbon atoms, in which 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-, or -NR m - with R m chosen from H or a Ci-Ce alkyl group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two, Ci-Ce alkyl, Ci-Ce alkoxy, hydroxyl, nitro, cyano, halogen atom, or Ci-Ce haloalkyl group.

[0143] Preferably, L1 represents a bond of -O-, -S(O)2-, -C(O)-, or an aliphatic chain of 1 to 20 carbon atoms, wherein 1 to 4 (preferably 1 to 2) methylene unit(s) (preferably non-adjacent) is / are optionally replaced by an arylene, -C(O)-, -O-, -S-, -S(O)-, or -S(O)2- group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two, substituents preferably selected from a Ci-Ce alkyl, Ci-Ce alkoxy, or Ci-Ce haloalkyl group. In particular, L1 may comprise one or two divalent aromatic groups, such as phenylenes.In particular, Li represents a G1-G2-G3 radical where G1 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 include one or two divalent aromatic groups, such as phenylenes, and may be substituted by one or more, in particular one or two, preferably chosen from a Ci-Ce alkyl, Ci-Ce alkoxy, or Ci-Ce haloalkyl.

[0144] Advantageously, L1 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, -C(O)-, -O-, -S-, -S(O)-, -S(O)2- group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two group(s) preferably selected from a Ci-Ce alkyl, Ci-Ce alkoxy, or Ci-Ce haloalkyl.

[0145] Advantageously, L1 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, -C(O)-, -O- group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two Ci-Ce alkyl, Ci-Ce alkoxy, hydroxyl, nitro, cyano, halogen atom, Ci-Ce haloalkyl group, typically substituted or unsubstituted by a Ci-Ce alkyl, Ci-Ce alkoxy, halogen atom, or Ci-Ce haloalkyl group.

[0146] In particular, X can independently represent a C1-C6 alkyl group, a hydroxyl group, or a halogen atom.

[0147] Advantageously, n represents 0 or 1.

[0148] Preferably, Y can independently represent a C1-C6 alkyl group, a hydroxyl group, or a halogen atom.

[0149] Advantageously, m represents 0 or 1.

[0150] According to particular variants, n and m independently represent 0 or 1, and X and Y independently represent a Ci-Ce alkyl group, a hydroxyl, or a halogen atom.

[0151] In other particular embodiments, the cyclic carboxylic polyanhydride comprises or is made up of a compound of formula (II) or preferably of formula (Ha): in which Zi is absent or represents a -CH2- (methylene) or -NH- group, preferably Z1 is absent or represents a -CH2- group,

[0152] Z2 is absent or represents a -CH2- (methylene) or -NH- group, preferably Z2 is absent or represents a -CH2- group,

[0153] Ai represents: o a CC bond or a C=C bond linking the four carbon atoms of the two carboxylic anhydride functions, o a saturated, unsaturated or aromatic carbocycle, said carbocycle comprising from 4 to 30 carbon atoms, or o a saturated, unsaturated or aromatic heterocycle, said heterocycle comprising from 4 to 30 carbon atoms, and said carbocycle or heterocycle being substituted or unsubstituted by one or more substituents, including a Ci-Ce alkyl group, a Ci-Ce haloalkyl group, a hydroxyl, a Ci-Ce alkoxy, nitro, cyano, or halogen atom.

[0154] Preferably, in formula (II), Z1 is absent or represents a -CH2- group and Z2 is absent or represents a -CH2- group.

[0155] In some variations, Ai represents a polycyclic carbocycle or heterocycle of 10 to 30 members. In these variations, the polycyclic group may include fused rings. Advantageously, Ai represents a polycyclic aromatic carbocycle or heterocycle of 10 to 30 members, comprising two or more fused rings. It may, in particular, be a naphthalene group.

[0156] Depending on the variant, Ai represents an aromatic carbocycle comprising 6 to 10 carbon atoms, such as a phenyl or a naphthalene.

[0157] 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.

[0158] Depending on variants, at least one of at least one cyclic carboxylic polyanhydride comprises or is made up of a compound of formula (III): in which <! représente une liaison C-C simple ou double,

[0159] L2 and L3 taken together with the carbon atoms to which they are bonded represent a saturated, unsaturated or aromatic carbocycle or heterocycle, optionally bridged, 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 selected from a Ci-Ce alkyl group, a hydroxyl, Ci-Ce alkoxy, nitro, cyano, or halogen atom.

[0160] Preferably, L2 and L3 taken together with the carbon atoms to which they are bonded represent a saturated, unsaturated or aromatic carbocycle, optionally bridged, said carbocycle comprising from 4 to 10 carbon atoms, and said carbocycle being substituted or unsubstituted by one or more (in particular 1 or 2) substituents selected from a Ci-Ce alkyl group or a halogen atom.

[0161] Advantageously, L2 and L3 taken together with the carbon atoms to which they are bonded represent:

[0162] • a saturated or unsaturated carbocycle, optionally bridged, comprising 4 to 8 carbon atoms, substituted or unsubstituted by one or more (in particular 1 or 2) substituents selected from a Ci-Ce alkyl group, halogen atom, or

[0163] • 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.

[0164] In particular, L2 and L3 taken together with the carbon atoms to which they are bonded can represent a cyclobutyl, cyclopentyl, cyclohexyl, bicyclo[2.2.2]oct-2-enyl, or phenyl.

[0165] Depending on the variant, the cyclic carboxylic polyanhydride comprises or is made up of a compound of formula (IV): in which 'I represents a single or double DC connection.

[0166] According to preferred embodiments, the cyclic carboxylic polyanhydride is chosen from the group consisting of: [Table 1] and a mixture of these.

[0167] Preferably, the cyclic carboxylic polyanhydride is BDTA, DPADA, BPDA and ODPA, or a mixture of these.

[0168] Cyclic carboxylic polyanhydrides, particularly the cyclic bis-carboxylic 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 the following groups:

[0169] Homophthalic: the syntheses described in US 6,797,838 may be used or adapted;

[0170] Isatoic: the syntheses described in "Sonochimie ultrasonique", Volume 14, Number 5, July 2007, pages 497-501, can be used or adapted.

[0171] Metal triflate or trifluoromethylsulfonate

[0172] Metal triflate or trifluoromethylsulfonate is chosen from among the triflates with the generic formula:

[0173] [CF3-S(=O)2-O1n, [M n+ ]

[0174] Or :

[0175] [M n+[ ] corresponds to the cation of a metal raised to the oxidation state +n, n being 1, 2, or 3, and the metal M being chosen from scandium, yttrium, the lanthanides, bismuth, gallium, indium, tin, thallium, aluminum, iron, copper, zinc, cadmium, titanium, zirconium, niobium, ruthenium, silver, tungsten, platinum, and hafnium; CF3S(=O)2-O" is the triflate or trifluoromethylsulfonate anion. According to particular embodiments of the invention, the metal triflate or trifluoromethylsulfonate is scandium triflate, bismuth triflate, or iron triflate.

[0176] Crosslinking

[0177] Advantageously, the crosslinking step comprises the following steps: a) contacting 100 parts by weight of at least one glycerol polyester and a diacid or carboxylic diester aliphatic monomer with 0.1 to 200 parts by weight of at least one cyclic carboxylic polyanhydride as defined herein, to obtain a crosslinking precursor mixture, in the presence of 0.0001 wt% (0.1 ppm) to 1 wt% (10000 ppm) of a metal triflate or trifluoromethylsulfonate relative to the mass of glycerol polyester and a diacid or carboxylic diester aliphatic monomer; b) pressurizing the mixture obtained in the crosslinking precursor step of step a) to a target temperature T c between 60°C and 175°C, and maintenance (at temperature T c and under pressure) for a heating time under pressure sufficient to obtain a crosslinked polyester, c) cooling and recovery of the crosslinked polyester.

[0178] At least one polyester of glycerol and of an aliphatic diacid or carboxylic diester monomer, at least one cyclic carboxylic polyanhydride and of metal triflate or trifluoromethylsulfonate are as defined above.

[0179] Typically, step a) includes contacting 100 parts by weight of at least one polyester of glycerol and an aliphatic diacid or carboxylic diester monomer, with 10 to 100, in particular 15 to 90, parts by weight of at least one cyclic carboxylic polyanhydride.

[0180] Typically, the amount of metal triflate (or trifluoromethylsulfonate) compound used in step a) varies in the range of 0.05 wt% (500 ppm) to 1 wt% (10000 ppm), preferably in the range of 0.1 wt% (1000 ppm) to 0.9 wt% (9000 ppm), relative to the mass of polyester of glycerol and a diacid aliphatic monomer or carboxylic diester.

[0181] Typically, step a) involves contacting 100 parts by weight of at least one glycerol polyester and an aliphatic diacid or carboxylic diester monomer with 10 to 100, in particular 15 to 90, parts by weight of at least one cyclic carboxylic polyanhydride in the presence of 0.1 wt% (1000 ppm) to 0.9 wt% (9000 ppm) of a metal triflate (or trifluoromethylsulfonate) compound relative to the mass of the glycerol polyester and the aliphatic diacid or carboxylic diester monomer. Preferably, step a) of contacting is carried out in the absence of solvent or diluent. According to one embodiment of the invention, step a) of contacting is carried out in the absence of any other additive.

[0182] According to another embodiment of the invention, at least one molecule or compound of interest can be added at this stage of the process during step a).

[0183] Step a) comprises a mixture of at least one glycerol polyester and an aliphatic diacid or carboxylic diester monomer and at least one cyclic carboxylic polyanhydride, preferably at a temperature T a allowing the fusion of the glycerol polyester and a diacid or carboxylic diester monomer, and preferably a homogeneous dispersion of the cyclic carboxylic polyanhydride. Thus, T a is typically between 20°C and 100°C, particularly between 30°C and 80°C.

[0184] Step a) involves using a metal triflate or trifluoromethylsulfonate as a catalyst. This can be introduced directly into the mixture in solid form.

[0185] To promote homogenization, agitation can be implemented in a known manner. Thus, step a) is typically carried out under agitation.

[0186] According to particular variants of the invention, the contact is made by introducing the cyclic carboxylic polyanhydride in solid form and the metal triflate or trifluoromethylsulfonate in solid form.

[0187] Advantageously, in step b), a platen press will be used, the plates of which have been preheated to temperature T c .

[0188] In step b), the temperature T c is typically between 60°C and 175°C, preferably 80°C and 175°C, preferably between 100°C and 160°C, preferably still from 120° to 150°C. 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.

[0189] The heating time is determined by the duration between the moment the press is closed and the moment it is opened.

[0190] Generally, the heating time t C h is between 10 and 2000 min.

[0191] During step c), the crosslinked polyester is typically cooled and recovered at room temperature and atmospheric pressure.

[0192] II. Crosslinking Composition

[0193] The present invention also relates to a crosslinking composition, comprising: o 100 parts by weight of at least one polyester of glycerol and of an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, Tl o of 0.1 to 200 parts by weight of at least one cyclic polycarboxylic anhydride as defined above, o of 0.0001% by mass (0.1 ppm) to 1% by mass (10000 ppm) relative to the mass of polyester of glycerol, of a metal triflate or trifluoromethylsulfonate.

[0194] Preferably, the composition comprises from 10 to 100, in particular from 15 to 90, parts by weight of at least one cyclic carboxylic polyanhydride.

[0195] Preferably the composition comprises 0.05 wt% (500 ppm) to 1 wt% (10000 ppm) of metal triflate or trifluoromethylsulfonate, preferably also 0.1 wt% (1000 ppm) to 0.9 wt% (9000 ppm) relative to the mass of glycerol polyester.

[0196] The polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, as well as cyclic carboxylic polyanhydride and metal triflate or trifluoromethylsulfonate, may be as defined above.

[0197] EXAMPLES

[0198] The following examples are given for illustrative purposes only, but should in no way be considered as limiting the present invention.

[0199] 1. Materials and methods

[0200] 1.1. Characteristics of the starting products

[0201] Glycerol and sebaceous acid polyester

[0202] [Table 2]

[0203] Procedure for the synthesis of the starting glycerol and sebacic acid polyester:

[0204] In a 10L double-walled stainless steel reactor equipped with an instrumented distillation column configured for total reflux and a condenser connected to a distillate recovery vessel, glycerol (1.94 kg, 1 molar equivalent) is mixed with water (0.56 kg) at 40 °C under a nitrogen flow (0.5 L / min). Gentle stirring is applied (20 rpm) for 5 minutes. After the glycerol has dissolved, sebacic acid (4.25 kg, 1 molar equivalent) is added to the aqueous mixture in the reactor. Finally, the remaining water (0.56 kg) is added. The reactor vessel is then gradually heated, following a progressive temperature ramp with intermediate stops, until a shell temperature of 172 °C is reached after 5 hours, corresponding to a medium temperature of 170 °C, measured using an immersion probe. The stirring speed is increased to 80 rpm when the temperature of the medium exceeds 90°C. The medium is left under reflux at the beginning of the test.When the vapor temperature at the top of the distillation column reaches 98°C, and after an equilibration time of 15 min, the column configuration is switched to total draw-off in order to selectively recover the water produced during the reaction.

[0205] The esterification of the medium is carried out over a total period of 8 hours and 30 minutes, starting from the moment the distillation begins, approximately 30 minutes after the introduction of the reagents. The water distilled during the test is collected in a dedicated insulated recovery container.

[0206] Next, a vacuum system is connected to the distillation condenser, and a pressure lower than atmospheric pressure is applied to the reactor contents. The pressure is reduced slowly and in steps (approximately 10 to 15% per step) over about 30 minutes until a target value of less than 30 mbar is reached.

[0207] Once the pressure in the reaction vessel stabilizes at 28 mbar, the medium is left to react at 170 °C for an additional 4 hours. During this polycondensation step, the stirring speed is maintained at 80 rpm.

[0208] The PGS produced is transferred from the reactor vessel to a container and allowed to 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.

[0209] cyclic carboxylic polyanhydride

[0210] [Table 3]

[0211] These compounds are commercially available, notably from Sigma-Aldrich.

[0212] 1.2. Measurement Methods

[0213] Measurement of crosslinking kinetics

[0214] The crosslinking kinetics were conducted using an ANTON PAAR MCR. The measurements consisted of monitoring the evolution of the elastic modulus of the compositions at 140°C, 120°C, and 100°C, depending on the composition, with 1% strain and a frequency of 1 Hz. The crosslinking times of the different compositions were measured until the elastic modulus reached a value of 1 MPa.

[0215] Macrostructure analysis: SEC RI

[0216] The SEC (Size Exclusion Chromatography) technique separates macromolecules in solution according to their size using columns filled with a porous gel. The macromolecules are separated according to their hydrodynamic volume, with the largest being eluted first.

[0217] While not an absolute method, SEC allows us to understand the molar mass distribution of a polymer. From commercial standard products, the various number-average molar masses (Mn) and weight-average molar masses (Mw) can be determined, and the polydispersity index (Ip = Mw / Mn), also called "polydispersity," can be calculated.

[0218] The macrostructure of non-crosslinked polyesters is analyzed by size-exclusion chromatography with differential refractometer detection (SEC RI), using low-weight polystyrene (PS) calibration with medium-weight standards. Samples are dissolved at a concentration of approximately 1 g / L in butylated hydroxytoluene (BHT)-free THF and stirred for two hours before injection. The analysis temperature is 35°C, with a mobile phase flow rate of 1 mL / minute on Agilent 2 Mixed E + 2 Mixed 2 columns.

[0219] Measurement of in vitro degradation

[0220] Cross-linked polyester discs with a diameter of 10 mm and a thickness of 2 mm are prepared and weighed. They are then individually incubated in aseptic TP30 bottles containing 20 ml of phosphate-buffered saline (PBS) solution at a temperature of 37.5°C. Discs are sampled at different times. For each weighing, the sample is first dried in an oven at 60°C for 7 days prior to weighing. The percentage weight loss for each measurement is calculated from the initial dry weight (i.e., at t = 0).

[0221] 2. Results

[0222] 2.1. Tested Formulations

[0223] The compositions studied are presented below. The contents are expressed as mass percentages and ppm (parts per million) relative to the mass of polyester of glycerol for the metal triflate (or trifluoromethylsulfonate) compound.

[0224] The reference mixture T for each comparison is a mixture comprising a high molecular weight poly(glycerol sebacate) polymer and a cyclic carboxylic polyanhydride (i.e., crosslinked in the absence of metal triflate or trifluoromethylsulfonate). The preparation protocol used is the same as that described in section 2.2, but in the absence of metal triflate or trifluoromethylsulfonate. • Bismuth Triflate

[0225] [Table 4]

[0226] • Iron III triflate

[0227] [Table 5] • Scandium Triflate

[0228] [Table 6]

[0229] • Bismuth triflate

[0230] [Table?]

[0231] • Iron III Triflate [Table 8] • Scandium Triflate

[0232] [Table 9]

[0233] 2.2. Protocol for the preparation of crosslinked polyesters

[0234] Step a)

[0235] Place a 100mL beaker on a hot plate equipped with a PT100 probe to control the temperature.

[0236] Introduce the poly(glycerol sebacate).

[0237] Heat the polymer to 50°C while mixing it with a spatula.

[0238] Add the quantity of bis anhydride.

[0239] In another method of preparation, add the quantity of metal triflate to the different proportions.

[0240] Mix with a spatula until a homogeneous mixture is obtained.

[0241] Cool to room temperature.

[0242] Step b): crosslinking

[0243] Crosslinking is carried out at 140°C, 120°C and 100°C depending on the compositions in the MCR rheometer during the measurement of the crosslinking kinetics according to the method described above in point 1.2. Crosslinking within the framework of this test protocol corresponds to obtaining a crosslinked polyester with an elastic modulus of 1MPa.

[0244] 2.3. Characterization of the crosslinking rates of crosslinked polyesters

[0245] • Properties with Bismuth Triflate

[0246] [Table 10]

[0247] [Table 11] [Table 12]

[0248] • Properties with Iron III Triflate

[0249] [Table 13] • Properties with Scandium Triflate

[0250] [Table 14]

[0251] • Properties BPADA29% with Bismuth Triflate

[0252] [Table 15]

[0253] • Properties of BPADA29% with Iron III Triflate [Table 16] 2.4. Characterization of the degradation of crosslinked polyesters

[0254] [Table 18]

[0255] 3. Discussion

[0256] Unexpectedly, a systematic and highly significant reduction in crosslinking time was observed for all compositions comprising the polyanhydride compound with metal triflate in various proportions. It was also found that the invention is effective at 140°C but remains operational at lower temperatures such as 120°C or 100°C.

[0257] Furthermore, it is also observed, after 7 days of incubation, that practically all compositions according to the present invention lead to similar mass losses compared to the reference composition T.

Claims

DEMANDS 1. A process for preparing a crosslinked glycerol polyester and an aliphatic monomer selected from a dicarboxylic acid and a dicarboxylic acid diester, comprising a step of crosslinking a glycerol polyester and an aliphatic monomer selected from a dicarboxylic acid and a dicarboxylic acid diester with a cyclic carboxylic polyanhydride A in the presence of a metal triflate compound, the cyclic carboxylic polyanhydride A comprising at least two cyclic carboxylic anhydride groups, the cyclic carboxylic polyanhydride A not comprising a linear carboxylic anhydride function, and the metal of the metal triflate compound being selected from scandium, yttrium, the lanthanides, bismuth, gallium, indium, tin, thallium, aluminum, iron, copper, zinc, cadmium, titanium, zirconium, the niobium, ruthenium, silver, tungsten, platinum and hafnium.

2. A process according to claim 1, wherein the aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid has the formula [R'OOC- (CH2) P -COOR'], in which p is a number from 1 to 30, preferably a number from 1 to 10, preferably p=8, and R' represents H or each R' represents, independently of each other, a linear or branched alkyl, in C1-C10, preferably in C1-C4, preferably methyl or ethyl.

3. A method according to claim 1 or 2, wherein the cyclic carboxylic anhydride groups of the cyclic carboxylic polyanhydride A are independently selected from ortho phthalic, succinic, maleic, homo phthalic and isatoic groups, preferably from ortho phthalic, succinic, maleic and homo phthalic groups.

4. 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, The representative -O- ; -S- ; -S(O)- ; -S(O)2- ; -C(O)- ; -NR n R n - with R n and R n 'independently chosen from H or an alkyl group in Ci-Ce, 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 devoid of linear anhydride groups.

5. A process according to any one of the preceding claims, wherein the cyclic carboxylic polyanhydride A comprises or is a compound of formula (I) or (H): in which Li represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -NR n R n - with R n and R n 'independently chosen from H or an alkyl group in Ci-Ce; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which 1 to 6 methylene unit(s) is / are optionally replaced by an arylene group, a heteroarylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, -NR m - with R m chosen from H or an alkyl group in Ci-, Ce, -P-, -P(O)-, -SiRaRb- with R a and Rb independently representing a -OH, Ci-Ce alkyl or Ci-Ce alkoxy group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two Ci-Ce alkyl, Ci-Ce alkoxy, hydroxyl, nitro, cyano, halogen, or Ci-Ce haloalkyl groups, Zi is absent or represents a -CH2- (methylene) or -NH- group, preferably Z1 is absent or represents a -CH2- group, Z2 is absent or represents a -CH2- (methylene) or -NH- group, preferably Z2 is absent or represents a -CH2- group, X represents, independently of each other, an alkyl group in Ci-Ce, a hydroxyl, alkoxy in Ci-Ce, nitro, cyano, or a halogen atom; n represents an integer from 0 to 3, preferably from 0 to 2. Y independently represents an alkyl group in Ci-Ce, a hydroxyl, alkoxy group in Ci-Ce, nitro, cyano, or a halogen atom, m represents an integer from 0 to 3, preferably from 0 to 2, Ai represents: - a C-C bond or a C=C bond linking 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 selected from a Ci-Ce alkyl group, a hydroxyl, a Ci-Ce alkoxy, nitro, cyano, or halogen atom.

6. A process according to any one of the preceding claims wherein the metal triflate compound is scandium triflate, bismuth triflate, or iron triflate.

7. A process 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 an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, with 0.1 to 200 parts by weight of at least one cyclic polycarboxylic anhydride as defined in any one of claims 1 to 4, in the presence of 0.0001% by mass (0.1 ppm) to 1% by mass (10000 ppm) relative to the mass of polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, of a triflate metal compound, the metal being selected from scandium, yttrium, lanthanides, bismuth, gallium, indium, tin, thallium, aluminium, iron, copper, zinc, cadmium, titanium, zirconium, niobium, ruthenium, silver, tungsten, platinum and hafnium, b) pressurizing the mixture obtained in the crosslinking precursor step of step a) to a target temperature T. c between 60°C and 175°C, preferably between 80°C and 175°C, and maintained at temperature Tc and under pressure for a heating time t C h sufficient to obtain a crosslinked polyester, c) cooling and recovery of the crosslinked polyester.

8. A method according to claim 7, wherein step a) comprises contacting 100 parts by weight of at least one polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, with 10 to 100 parts by weight of at least one cyclic carboxylic polyanhydride.

9. A method according to claim 7 or 8, wherein step a) comprises the use of 0.05 wt% (500 ppm) to 1 wt% (10,000 ppm), preferably ranging from 0.1% by mass (1000ppm) to 0.9% by mass (9000ppm), relative to the mass of polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, of a triflate (or trifluoromethylsulfonate) metal compound.

10. Crosslinking composition, comprising: - 100 parts by weight of at least one polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, - 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, - 0.0001 wt% (0.1 ppm) to 1 wt% (10000 ppm) relative to the polyester mass of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid, of a triflate metal compound, the metal being selected from scandium, yttrium, lanthanides, bismuth, gallium, indium, tin, thallium, aluminium, iron, copper, zinc, cadmium, titanium, zirconium, niobium, ruthenium, silver, tungsten, platinum and hafnium.

11. Composition according to claim 10, wherein the aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid has the formula [R'OOC-(CH2) P -COOR'], in which p is a number from 1 to 30, preferably a number from 1 to 10, and R' represents H or each R' represents, independently of each other, a linear or branched alkyl, in C1-C10, preferably in C1-C4, preferably also methyl or ethyl.

12. Composition according to claim 10 or 11, wherein the polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid or a diester of a dicarboxylic acid has a molar mass in number M n less than or equal to 10,000 g / mol, the number molar mass being determined by size exclusion chromatography (SEC / RI) analysis.

13. Composition according to any one of claims 10 to 12, wherein the cyclic carboxylic polyanhydride comprises a compound of formula (I) or (II): in which Li represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -NR n R n - with R n and R n 'independently chosen from H or an alkyl group in Ci-Ce; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which 1 to 6 methylene unit(s) is / are optionally replaced by an arylene group, a heteroarylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, -NR m - with R m chosen from H or an alkyl group in Ci-Ce, ; -P-, -P(O)-, -SiR a Rb- with R aand Rb independently representing a -OH, Ci-Ce alkyl or Ci-Ce alkoxy group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two Ci-Ce alkyl, Ci-Ce alkoxy, hydroxyl, nitro, cyano, halogen, or Ci-Ce haloalkyl groups, Zi is absent or represents a -CH2- (methylene) or -NH- group, preferably Z1 is absent or represents a -CH2- group, Z2 is absent or represents a -CH2- (methylene) or -NH- group, preferably Z2 is absent or represents a -CH2- group, X represents, independently of each other, an alkyl group in Ci-Ce, a hydroxyl, alkoxy in Ci-Ce, nitro, cyano, or a halogen atom; n represents an integer from 0 to 3, preferably from 0 to 2. Y represents independently of each other an alkyl group in Ci-Ce, a hydroxyl, alkoxy in Ci-Ce, nitro, cyano, or a halogen atom, m represents an integer from 0 to 3, preferably from 0 to 2. Ai represents: - a C-C bond or a C=C bond linking 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 selected from a Ci-Ce alkyl group, a hydroxyl, a C1-Ce alkoxy, nitro, cyano, or halogen atom.

14. Composition according to any one of claims 10 to 13, wherein the metal triflate compound is selected from scandium triflate, bismuth triflate and iron triflate.

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