Crosslinked polyesters of glycerol having improved bioresorbability and / or improved degradation in aqueous medium

Abstract

The present invention relates to the use of a cyclic carboxylic polyanhydride A, the cyclic carboxylic polyanhydride A comprising at least two cyclic carboxylic anhydride groups, and not comprising a linear carboxylic anhydride function, as a crosslinking agent for a polyester of glycerol and of an aliphatic carboxylic diacid or diester monomer, so as to increase the bioresorbability and / or degradation in aqueous medium of a polyester of glycerol and of a crosslinked aliphatic carboxylic diacid or diester monomer, in particular compared to a polyester of glycerol and of a thermally crosslinked aliphatic carboxylic diacid or diester monomer in the absence of a crosslinking agent, and advantageously in the absence of cyclic carboxylic polyanhydride A.

Description

[0001] DESCRIPTION

[0002] TITLE: Crosslinked polyesters of glycerol with improved bioresorbability and / or degradation in aqueous media

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to crosslinked polyesters of glycerol having improved bioresorbability and / or degradation in aqueous media.

[0005] STATE OF THE ART

[0006] Biodegradable and / or bio-sourced 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 application areas.

[0007] These polyesters are generally poorly biodegradable, which limits their use as a resorbable biomaterial or to encapsulate an organic molecule.

[0008] There is therefore a need for crosslinked polyesters that are more bioresorbable, and / or with better biodegradability, particularly in aqueous environments, but retaining mechanical properties suitable for the intended short-term uses.

[0009] STATEMENT OF THE INVENTION

[0010] 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.

[0011] Thus, the present invention relates to the use of a cyclic carboxylic polyanhydride A, the cyclic carboxylic polyanhydride A comprising at least two cyclic carboxylic anhydride groups, and not comprising a linear carboxylic anhydride function, as a crosslinking agent for a glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid, so as to increase the bioresorbability and / or the degradation in aqueous medium of a glycerol polyester of an aliphatic monomer chosen from a dicarboxylic acid and a diester of a crosslinked dicarboxylic acid, in particular compared to a glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a thermally crosslinked dicarboxylic acid in the absence of a crosslinking agent, and advantageously in the absence of cyclic carboxylic polyanhydride A.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.

[0012] L representing -O- ; -S- ; -S(O)- ; -S(O)2- ; -C(O)- ; -NR n Rn- with R n and R n ' independently chosen from H or a C 1 -C 6 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.

[0013] Preferably, the cyclic polycarboxylic anhydride A comprises or consists of a compound of formula (I) or (II): in which

[0014] • Li represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -NR n Rn- with R n and R n' independently selected from H or a C 1 -C 6 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-; -NR m - with R m selected from H or a C 1 -C 6 alkyl group; -P-; -P(O)-; -SiR a Rb- with R a and Rb representing independently of one another a group -OH, C 1 -C 6 alkyl or C 1 -C 6 alkoxy, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, a hydroxyl, nitro, cyano, halogen atom, C 1 -C 6 haloalkyl group,

[0015] • Zi is absent or represents a -CH2- (methylene) or -NH- group, preferably Zi is absent or represents a -CH2- group,

[0016] • Z2 is absent or represents a -CH2- (methylene) or -NH- group, preferably Z2 is absent or represents a -CH2- group

[0017] • X represents, independently of one another, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom,

[0018] • n represents an integer ranging from 0 to 3, preferably from 0 to 2,

[0019] • Y represents, independently of one another, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom,

[0020] • m represents an integer ranging from 0 to 3, preferably from 0 to 2,

[0021] • Ai represents: o A CC bond or a C=C bond connecting 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, and 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 chosen from a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or halogen atom.

[0022] Preferably, Zi is absent or represents a -CH2- group, and Z2 is absent or represents a -CH2- group,

[0023] In particular, Li represents a bond or an aliphatic chain of 1 to 6 carbon atoms, in which one or two methylene units is (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 a C1-C6 alkyl, C1-C6 alkoxy, or C1-C6 haloalkyl.

[0024] Advantageously, the cyclic polycarboxylic anhydride A may comprise or consist of a compound of formula (III) or (IV): in which î|

[0025] <' represents a single or double C-C bond, l_2 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 C-C 6 alkyl group, a hydroxyl, C-C 6 alkoxy, nitro, cyano, or a halogen atom.

[0026] The invention also relates to a crosslinked polyester obtained by crosslinking a glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid with at least one cyclic carboxylic polyanhydride A as defined herein, with a mass loss at 7 days after in vitro incubation at 37.5°C in a phosphate buffer saline solution (PBS buffer) and drying at 60°C greater than or equal to 5%. The polyester may in particular be obtained by crosslinking: o 100 parts by weight of at least one glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid of number-average molar mass M n less than or equal to 10,000 g / mol, o with from 10 to 100, preferably from 20 to 50, parts by weight of the cyclic polycarboxylic anhydride A as defined herein.

[0027] In particular, the inventors have demonstrated that a polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid crosslinked with at least one cyclic polycarboxylic anhydride A as crosslinking agent exhibited a significant increase in their mass loss at 7 days after in vitro incubation at 37.5°C in a phosphate buffer saline solution (PBS buffer) and drying at 60°C, in particular compared to the polyester of glycerol and an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid thermally crosslinked in the absence of crosslinking agent, and advantageously in the absence of cyclic polycarboxylic anhydride A.

[0028] Advantageously, the crosslinked polyester obtained by crosslinking a glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid with at least one cyclic carboxylic polyanhydride A as defined here as crosslinking agent has a mass loss at 7 days after in vitro incubation at 37.5°C in a PBS buffer and drying at 60°C greater than or equal to 5%.

[0029] Preferably, the crosslinked polyester has a Shore A hardness measured according to ASTM D 2240:2021 at room temperature ranging from 20 to 80, typically from 20 to 50.

[0030] Advantageously, the crosslinked polyester has a molar mass in number M n less than or equal to 10,000 g / mol.

[0031] Typically, the dicarboxylic acid monomer or the carboxylic diester monomer has the general formula R'OOC-(CH2) P-COOR', in which p represents an integer ranging from 1 to 30, preferably an integer ranging from 1 to 10, more preferably p=8, and R' represents H or each R' represents, independently of one another, a linear or branched alkyl, C1-C10, preferably C1-C4, more preferably methyl or ethyl.

[0032] DETAILED DESCRIPTION OF THE INVENTION

[0033] DEFINITIONS

[0034] For the purposes of the present invention, the term “a” or “an” means “one or more” or “at least one”.

[0035] 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 strictly greater than a to strictly less than b (i.e. excluding the limits a and b), while any range of values ​​designated by the expression "from aab" represents the range of values ​​of aab, i.e. including the strict limits a and b.

[0036] In this description, the term "approximately" means that the value concerned may be 10% lower or higher, in particular 5%, in particular 1%, than the value indicated. 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 monomers, that is to say in particular glycerol, dicarboxylic acid monomer and cyclic polycarboxylic anhydride.

[0037] OH

[0038] HO / . OH

[0039] Glycerol is a triol with the following formula:

[0040] 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.

[0041] In the present invention, a "carboxylic anhydride function" has the formula - C(=O)-OC(=O)-. This function is divalent.

[0042] In the present invention, a “nitrogenous carboxylic anhydride function” corresponds to the formula -C(=O)-OC(=O)-NH-. This function is divalent.

[0043] 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.

[0044] 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. A "linear anhydride group" is understood as 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.

[0045] In the present invention, a "monovalent hydrocarbon group" means a saturated, unsaturated or aromatic, cyclic or acyclic (linear or branched) monovalent hydrocarbon chain comprising from 1 to 40 carbon atoms. A monovalent hydrocarbon group includes, in particular, 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.

[0046] 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 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 a substituted or unsubstituted C1-C40 alkanediyl (linear or branched), alkenediyl (linear or branched), cycloalkanediyl, cycloalkenediyl group.

[0047] 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) or aromatic, cyclic or acyclic (linear or branched), comprising from 1 to 40 carbon atoms.

[0048] By "aliphatic" is meant a linear, branched and / or cyclic hydrocarbon group, whether saturated or unsaturated but not aromatic.

[0049] 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. By way of example, mention may be made of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl or hexyl groups.

[0050] 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. Examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cycloheptyl groups. An example of a polycyclic cycloalkyl is adamantyl.

[0051] 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.

[0052] 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. Examples include cyclobutenyl, cyclopentenyl, cyclohexenyl or cycloheptenyl groups. An example of a polycyclic cycloalkenyl is bicyclo[2.2.2]oct-7-ene.

[0053] For the purposes of the present invention, the term “alkynyl” group means a monovalent, linear or branched hydrocarbon chain comprising at least one triple bond and comprising from 2 to 40 carbon atoms. By way of example, mention may be made of ethynyl, propynyl, butynyl, pentynyl or hexynyl groups.

[0054] 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. By way of example, the cycloheptynyl group may be mentioned.

[0055] 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.

[0056] 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, propanediyl, butanediyl, pentanediyl, or hexanediyl group.

[0057] For the purposes of the present invention, the term “cycloalkanediyl” 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.

[0058] For the purposes of the present invention, the term “alkenediyl” 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.

[0059] For the purposes of the present invention, the term “cycloalkenediyl” group means 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.

[0060] By “alkynediyl” group is meant, for the purposes of the present invention, a divalent, linear or branched, acyclic hydrocarbon chain, comprising from 2 to 40 carbon atoms and at least one triple bond.

[0061] 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.

[0062] For the purposes of the present invention, the term “C1-C6 alkoxy” group means 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, iso-propoxy, n-butoxy, sec-butoxy, t-butoxy, n-pentoxy, or n-hexoxy groups.

[0063] 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. For the purposes of the present invention, the term "C1-C6 haloalkyl" 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, the trifluoromethyl group (-CF3) may be mentioned.

[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, joined or bridged rings. The carbocycle may be saturated (i.e., not comprise any unsaturation or multiple bonds), unsaturated (i.e., comprise at least one double bond or optionally one triple bond, without being aromatic), or aromatic.

[0066] When the carbocycle is aromatic, we speak of an “aryl” group.

[0067] By "heterocycle comprising from 4 to 30 carbon atoms" is meant, for the purposes 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, thiazolidine, isothiazolidine, oxazocane, thiazepane, benzimidazolone.

[0068] 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.

[0069] An “arylene group” means a divalent aromatic hydrocarbon group, preferably comprising 6 to 10 carbon atoms, and comprising one or more fused rings, such as, for example, a phenyl or naphthyl group. Advantageously, this is phenylene.

[0070] A "heteroarylene group" means a divalent aromatic heterocycle, comprising 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. Pyridinylene may be cited as an example.

[0071] According to the invention, an “orthophthalic group” means a group of formula: , preferably of group formula being linked to the rest of the polyanhydride molecule by the bond • , or of a divalent group of formula: , this group being linked to the rest of the polyanhydride molecule by bond I on the one hand, and by bond 1 on the other hand. The orthophthalic group may be substituted or unsubstituted. In the present invention, a "succinic group" means a monovalent group of formula group being linked to the rest of the polyanhydride molecule by bond I and which may be substituted or unsubstituted, or of a divalent group of formula:

[0072] O

[0073] °, this group being linked to the rest of the polyanhydride molecule by the i bond 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.

[0074] In the present invention, a "maleic group" means a monovalent group of formula group being linked to the rest of the polyanhydride molecule by the bond i and which may be substituted or unsubstituted, or of a divalent group of formula:

[0075] O

[0076] ° l, this group then being linked to the rest of the polyanhydride molecule by the

[0077] - - 1 - bond i on the one hand, and by bond I 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.

[0078] In the present invention, a "homo-phthalic group" means a group of formula: preference of grouping formula being connected 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 i bond on the one hand, and by the I bond on the other hand. The homophthalic group can be substituted or unsubstituted.

[0079] In the present invention, an "isatoic group" means a group of formula: group being linked to the rest of the polyanhydride molecule by the i bond, or a polyanhydride molecule by the i bond on the one hand, and by the l bond on the other hand. The isatoic group can be substituted or unsubstituted.

[0080] By "room temperature" is meant here a temperature generally ranging from 15°C to 40°C, preferably from 20°C to 30°C, in particular around 25°C.

[0081] As used herein, "bioresorbability" means the ability of a material, particularly a polymer such as a polyester, to be broken down (digested) naturally within a living organism. Bioresorbability depends on the ability to be broken down and on the speed of digestion of the product in the biological environment. Bioresorption is chemically expressed as a process of progressive deconstruction of the chemical structure of the polymer (polyester), in particular with the production of lower molecular weight metabolites, particularly monomers.

[0082] As used herein, "degradation" of a polyester means a chemical process involving, among other things, the hydrolysis of ester bonds, generating polymer molecules of lower molecular weight.

[0083] As used herein, an “aqueous medium” means an aqueous solution, generally saline, and typically buffered (in particular using a PBS buffer). The aqueous medium of the invention advantageously aims to reproduce the environment of the living organism (pH, saline concentration).

[0084] As used herein, a "PBS buffer," also called "phosphate buffered saline," means a saline solution buffered with a phosphate buffer. PBS buffers are well known in the art and are commercially available. They are typically a solution containing sodium chloride, disodium phosphate, monopotassium phosphate, and optionally potassium chloride. In general, the concentration of these salts is that of the human body (isotonicity). PBS buffer is therefore generally usable to reproduce the environment of the living organism.

[0085] Use of a cyclic polycarboxylic anhydride A as a crosslinking agent to increase bioresorbability and / or degradation in aqueous media

[0086] The invention relates to the use of a cyclic carboxylic polyanhydride A, the cyclic carboxylic polyanhydride A comprising at least two cyclic carboxylic anhydride groups, and not comprising a linear carboxylic anhydride function, as a crosslinking agent for a glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid, so as to increase the bioresorbability and / or the degradation in aqueous medium of the glycerol polyester and a crosslinked carboxylic diacid or diester aliphatic monomer, in particular compared to the glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a crosslinked dicarboxylic acid alone, i.e. compared to the glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a starting dicarboxylic acid which has undergone a purely thermal crosslinking,in particular in the absence of crosslinking agent, and advantageously in the absence of cyclic carboxylic polyanhydride A. The polyester of glycerol and of a thermally crosslinked aliphatic diacid or diester carboxylic monomer can be prepared according to the same process as that of the invention, but without the addition of polyanhydride. An example of implementation is given in the examples.,

[0087] The bioresorbability measured by the degradation in aqueous medium of the crosslinked polyesters obtained according to the invention is improved in particular at temperatures ranging from 20°C to 70°C, in particular from 25°C to 50°C, typically at 37.5°C, i.e. body temperature.

[0088] The bioresorbability and / or degradation in aqueous medium of the crosslinked polyesters obtained according to the invention is characterized in particular in the laboratory by a loss of mass, at 7 days after in vitro incubation at 37.5°C in a PBS buffer and drying at 60°C greater than or equal to 5% typically at atmospheric pressure. The loss of mass is calculated relative to the total weight of the initial crosslinked polyester (i.e. at day 0).

[0089] A "crosslinking agent" is an agent that aims to form one or more three-dimensional networks, by chemical means, in the polyester. Thus, the crosslinking agent aims to create chemical bonds (called bridges) between the macromolecular chains of the polyester, when the crosslinking reaction is carried out.

[0090] Thus, the invention also relates to a crosslinked polyester obtained by crosslinking a glycerol polyester and an aliphatic diacid or diester carboxylic monomer with, as crosslinking agent, at least one cyclic carboxylic polyanhydride A as defined below, with a loss of mass at 7 days after in vitro incubation at 37.5°C in a PBS buffer and drying at 60°C greater than or equal to 5%, or preferably greater than or equal to 7%.

[0091] Advantageously, the crosslinked polyester has a Shore A hardness measured according to the ASTM D 2240:2021 standard at room temperature ranging from 20 to 80, typically from 20 to 50.

[0092] The crosslinked polyester can be obtained by the process of the invention.

[0093] The crosslinked polyester is typically obtained by crosslinking: o 100 parts by weight of at least one glycerol polyester and an aliphatic diacid or diester carboxylic monomer, advantageously of number molar mass M n less than or equal to 10,000 g / mol, o from 10 to 100, preferably from 20 to 50, parts by weight of the cyclic polycarboxylic anhydride A.

[0094] Advantageously, the product of the crosslinking of the glycerol polyester and an aliphatic diacid or diester carboxylic monomer and the cyclic carboxylic polyanhydride A comprises only ester functions.

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

[0096] The starting glycerol polyester may 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, preferably from 4 to 36 carbon atoms.

[0097] According to preferred variants of the invention, the aliphatic dicarboxylic acid monomer is saturated, in particular linear or branched, preferably it is a (C3-C2o)alkanediyldicarboxylic acid, more preferably a (Cs-Ci5)alkanediyldicarboxylic acid. A (Cx-Cy)alkanediyl group is a divalent, saturated, linear or branched hydrocarbon group comprising from x to y carbon atoms.

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

[0099] In particular, according to these variants, 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.

[0100] 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] 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.

[0102] Preferably, the dicarboxylic acid monomer comprises or consists of sebacic acid. According to preferred variants of the invention, the dicarboxylic acid monomer and glycerol are the only monomers during the polycondensation.

[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 ranging from 1 to 30, preferably a number ranging from 1 to 10 and each R” represents, independently of one another, a linear or branched alkyl, C1-C10, preferably C1-C4, more preferably methyl or ethyl.

[0104] In particular, according to these variants of the invention, the alkyl diester monomer of dicarboxylic acid may 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 diesters of dicarboxylic acids, more preferably the diester of dicarboxylic acid 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. According to variants of the invention, the dicarboxylic acid diester monomer may be a mixture of at least two different dicarboxylic acid diesters. Preferably then, the dicarboxylic acid diester monomer comprises dimethyl sebacate.

[0105] According to preferred variants of the invention, the dicarboxylic acid diester monomer is dimethyl sebacate. According to preferred variants of the invention, the dicarboxylic acid diester monomer and glycerol are the only monomers. Very preferably then, the dimethyl sebacate monomer and glycerol are the only monomers.

[0106] Advantageously, the molar ratio of glycerol / diacid or diester carboxylic monomer varies from 1 / 2 to 10 / 1, in particular from 1 / 1 to 5 / 1, preferably from 1 / 1 to 2 / 1.

[0107] The polyester of glycerol and an aliphatic diacid or diester carboxylic monomer (hereinafter referred to as non-crosslinked polyester) advantageously has one or more of the following characteristics:

[0108] - 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;

[0109] - a number-average molar mass (Mn) of the non-crosslinked polyester less 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;

[0110] - a polydispersity Ip (Mw / Mn) of the non-crosslinked polyester of less than 10, preferably less than or equal to 8.

[0111] 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 monomer can be obtained in particular by implementing the processes described in FR2315383.

[0112] 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.

[0113] Cyclic polycarboxylic anhydride (before crosslinking)

[0114] Preferably, the cyclic polycarboxylic anhydride comprises two cyclic carboxylic anhydride functions, i.e. it is a cyclic bis-carboxylic anhydride. Advantageously, it is non-nitrogenous cyclic carboxylic anhydride functions.

[0115] 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, from orthophthalic, succinic, maleic and homophthalic groups.

[0116] 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. Advantageously, the cyclic carboxylic anhydride groups are independently orthophthalic, succinic or maleic groups.

[0117] 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,

[0118] L representing -O- ; -S- ; -S(O)- ; -S(O)2- ; -NR n - with R n chosen from H or a C1-C8 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

[0119] L being devoid of linear anhydride groups.

[0120] 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-C8 alkyl)- or -N(C1-C9 alkyl)-N(C1-C9 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.

[0121] 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.

[0122] 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 hydrocarbon group cyclic or acyclic, saturated, unsaturated or aromatic, 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.

[0123] The 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 a Ci-Ce alkyl group - depending on the valence of the atom.

[0124] 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.

[0125] 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.

[0126] 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 rings.

[0127] In particular embodiments, the cyclic polycarboxylic anhydride comprises or consists of a compound of formula (I) or preferably of formula (Ia): in which

[0128] • Li represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -NR n R n - with Rn and R n ' independently selected from H or a C 1 -C 6 alkyl group; -C(O)-; or an aliphatic hydrocarbon 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-; -NR m - with R m selected from H or a C 1 -C 6 alkyl group; -P-; -P(O)-; -SiR a Rb- with R a and Rb representing independently of one another a group -OH, C 1 -C 6 alkyl or C 1 -C 6 alkoxy, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two, C 1 -C 6 alkyl groups, C 1 -C 6 alkoxy, a hydroxyl, nitro, cyano, halogen atom, C 1 -C 6 haloalkyl,

[0129] • 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,

[0130] • X represents, independently of one another, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom,

[0131] • n represents an integer ranging from 0 to 3, preferably from 0 to 2,

[0132] • Y represents, independently of one another, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom,

[0133] • m represents an integer ranging from 0 to 3, preferably from 0 to 2.

[0134] Advantageously, Z1 is absent or represents a -CH2- group, and Z2is absent or represents a -CH2- group. Preferably, Z1 and Z2are the same. Advantageously, Z1 and Z2both represent a bond (which is equivalent to saying that Z1 and Z2are both absent).

[0135] Preferably, L1 represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -O(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-, -NR m - with R m chosen from H or a C 1 -C 6 alkyl group, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two, C 1 -C 6 alkyl groups, C 1 -C 6 alkoxy groups, a hydroxyl, nitro, cyano, a halogen atom, a C 1 -C 6 haloalkyl group.

[0136] Preferably, L1 represents a bond; -O-; -S(O)2-; -C(O)-; or an aliphatic chain of

[0137] 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-, 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-C8 alkoxy, or C1-C8 haloalkyl. In particular, L1 may comprise one or two divalent aromatic groups, such as phenylenes.

[0138] In particular, L1 represents a radical G1-G2-G3 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 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.

[0139] 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 from 1 to

[0140] 2 methylene unit(s) (preferably non-adjacent) is (are) optionally replaced by an arylene group, -C(O)-, -O-, -S-, -S(O)-, -S(O)2-, 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-C8 alkoxy, or C1-C8 haloalkyl.

[0141] 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-C8 alkoxy, hydroxyl, nitro, cyano, halogen atom, C1-C8 haloalkyl group, typically substituted or unsubstituted by C1-C6 alkyl, C1-C8 alkoxy, halogen atom, or C1-C8 haloalkyl group.

[0142] In particular, X may independently represent a C 1 -C 6 alkyl group, a hydroxyl, or a halogen atom.

[0143] Advantageously, n represents 0 or 1.

[0144] Preferably, Y represents, independently of one another, a C1-C8 alkyl group, a hydroxyl, or a halogen atom. Advantageously, m represents 0 or 1.

[0145] According to particular variants, n and m independently represent 0 or 1, and X and Y independently represent a C 1 -C 6 alkyl group, a hydroxyl, or a halogen atom.

[0146] In other particular embodiments, the cyclic polycarboxylic anhydride comprises or consists of a compound of formula (II) or preferably of formula (IIa): in which

[0147] Zi is absent or represents a -CH2- (methylene) or -NH- group, preferably Zi is absent or represents a -CH2- group,

[0148] Z2is absent or represents a -CH2- (methylene) or -NH- group, preferably Z2is absent or represents a -CH2- group,

[0149] Ai represents: o a CC bond or a C=C bond connecting 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, and 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, in particular a C1-C8 alkyl group, C1-C6 haloalkyl, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom.

[0150] Preferably, in formula (II), Zi is absent or represents a -CH2- group and Z2 is absent or represents a -CH2- group.

[0151] In some variants, Ai represents a polycyclic carbocycle or heterocycle with 10 to 30 members. In these variants, the polycyclic may comprise fused rings. Advantageously, Ai represents a polycyclic aromatic carbocycle or heterocycle with 10 to 30 members, comprising two or more fused rings. It may in particular be a naphthalene group.

[0152] Alternatively, Ai represents an aromatic carbocycle comprising from 6 to 10 carbon atoms, such as phenyl or naphthalene.

[0153] 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.

[0154] According to variants, the at least one of at least one cyclic carboxylic polyanhydride comprises or consists of a compound of formula (III): in which

[0155] 'I represents a single or double C-C bond, l_2 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 said carbocycle or heterocycle being substituted or unsubstituted by one or more substituents chosen from a C-C alkyl group, a hydroxyl, C-C 1 alkoxy, nitro, cyano, or a halogen atom.

[0156] Preferably, L2 and l_3 taken together with the carbon atoms to which they are linked 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 chosen from a C1-C6 alkyl group or a halogen atom.

[0157] Advantageously, l_2 and l_3 taken together with the carbon atoms to which they are bonded represent:

[0158] • 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 C 1 -C 6 alkyl group, halogen atom, or

[0159] • 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 C 1 -C 6 alkyl group, halogen atom.

[0160] In particular, l_2 and l_3 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.

[0161] According to variants, the cyclic polycarboxylic anhydride comprises or consists of a compound of formula (IV): in which <• represents a single or double CC bond.

[0162] According to preferred embodiments, the cyclic polycarboxylic anhydride of formula

[0163] (I) is chosen from the group consisting of:

[0164] [Table 1]

[0165] and a mixture of these.

[0166] Preferably, the cyclic polycarboxylic anhydride is BTDA, BPADA, BPDA and ODPA, or a mixture thereof.

[0167] 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:

[0168] Homophthalic: the syntheses described in US 6,797,838 may be used or adapted;

[0169] Isatoic: one can use or adapt the syntheses described in “Ultrasonic Sonochemistry”, Volume 14, Number 5, July 2007, pages 497-501.

[0170] Crosslinking

[0171] Advantageously, the crosslinking step comprises the following steps: a) bringing 100 parts by weight of at least one glycerol polyester and an aliphatic diacid or diester carboxylic monomer into contact with 10 to 100, preferably 20 to 50, parts by weight of at least one cyclic carboxylic polyanhydride as defined herein, to obtain a mixture of crosslinking precursors, b) pressurizing the mixture obtained in the crosslinking precursor step of step a) to a target temperature T c ranging from 100°C to 200°C, and maintaining (at temperature T cand under pressure) for a heating time under pressure tch sufficient to obtain a crosslinked polyester, c) cooling and recovery of the crosslinked polyester.

[0172] Typically, step a) comprises bringing into contact 100 parts by weight of at least one glycerol polyester and an aliphatic diacid or diester carboxylic monomer, with from 10 to 100, in particular from 15 to 90, parts by weight of at least one cyclic carboxylic polyanhydride.

[0173] Preferably, step a) of contacting is carried out in the absence of solvent, diluent or other additive.

[0174] Step a) comprises a mixture of at least one glycerol polyester and an aliphatic dicarboxylic acid or diester monomer and at least one cyclic carboxylic polyanhydride, preferably at a temperature T aallowing the fusion of the glycerol polyester and an aliphatic diacid or diester carboxylic monomer, and preferably a homogeneous dispersion of the cyclic polycarboxylic anhydride. Thus, T a typically varies from 20°C to 100°C, especially from 30°C to 80°C.

[0175] In order to promote homogenization, agitation can be implemented in a known manner. Thus, step a) is typically carried out with agitation.

[0176] According to particular features of the invention, the contacting is carried out by the introduction of the cyclic polycarboxylic anhydride in solid form.

[0177] Advantageously, in step b), a platen press will be used, the plates of which have been preheated to temperature T c .

[0178] In step b), the temperature T c is typically 110°C to 175°C, preferably 120°C to 160°C.

[0179] Advantageously, the overpressure applied by the press (relative to atmospheric pressure) in heating step b) varies from 0.5 bar to 5 bar (equivalent to 50 kPa to 500 kPa), in particular from 1 to 4 bar.

[0180] The heating time is determined by the time between the time the press is closed and the time it is opened.

[0181] Generally, the heating time t C h varies from 10 min to 2000 min.

[0182] In step c), the crosslinked polyester is typically cooled and recovered at room temperature and atmospheric pressure.

[0183] Polyanhydrides as crosslinking agents have the following advantages:

[0184] -Polyanhydrides allow the creation of an elastic network with crosslinking points with hydrolyzable ester groups. The material thus obtained preserves the degradation properties of polyester, in particular of the polyester of glycerol and sebacic acid, poly(glycerol sebacate).

[0185] - the reaction does not lead to the formation of by-products which could cause massive hydrolysis of the polyester chains, unlike polyacid chlorides which generate hydrogen chloride during the reaction.

[0186] -Another major advantage of polyanhydrides lies in the crosslinking process itself. Unlike polyacids, other possible crosslinking agents for poly(glycerol sebacate), which react with hydroxyl groups by esterification, the alcohol anhydride reaction requires less energy, thus promoting a reduction in crosslinking time or temperature. In addition, this reaction does not lead to the formation of water as a by-product, unlike the polyacid-alcohol reaction. This characteristic promotes efficient crosslinking in a closed mold, limiting the risk of bubble formation during crosslinking.

[0187] -Finally, in comparison with diisocyanates, whose use is described as crosslinking agents, forming urethane bonds that are little or not at all hydrolyzable, polyanhydrides represent a more advantageous alternative because they reduce toxicological risks.

[0188] METHODS

[0189] Shore A hardness measurement:

[0190] Shore A hardness measurements were performed using a portable Shore durometer according to ASTM D2240:2021 at room temperature (23°C±2°C).

[0191] Measurement of in vitro degradation:

[0192] Cross-linked polyester discs with a diameter of 10 mm and a thickness of 2 mm are made and weighed. They are then incubated individually in flasks (TP30 aseptic) containing 20 ml of a phosphate buffer saline solution (PBS buffer) and at a temperature of 37.5 ° C. Discs are taken at different dates. For each weighing, the sample is first dried in an oven at 60 ° C for 3 days before weighing. The percentage of weight loss for each reading is calculated from the initial dry weight (i.e. at t = 0).

[0193] Macrostructure analysis: SEC RI

[0194] The SEC (Size Exclusion Chromatography) technique separates macromolecules in solution according to their size through columns filled with a porous gel. The macromolecules are separated according to their hydrodynamic volume, with the largest being eluted first.

[0195] Although not an absolute method, SEC allows us to understand the distribution of molar masses of a polymer. From commercial standard products, the different number-average (Mn) and weight-average (Mw) molar masses can be determined and the polydispersity index (Ip = Mw / Mn), also called "dispersity", calculated.

[0196] The "macrostructure" of the 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 1 g / 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 1 mL / minute on 2 Mixed E + 2 Mixed 2 columns (marketed by Agilent).

[0197] EXAMPLES The following examples are given for illustrative purposes, but should in no way be considered as limiting the present invention.

[0198] 7. Materials and methods

[0199] Characteristics of the starting products

[0200] [Table 2]

[0201] Procedure for the synthesis of the starting glycerol and sebacic acid polyester (i.e. non-crosslinked):

[0202] In a 10L double-jacketed stainless steel reactor topped with an instrumented distillation column configured for 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 dissolution of 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 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 withdrawal in order to selectively recover the water produced during the reaction. 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 reactants. The water distilled during the test is recovered in a dedicated heat-insulated recovery pot. Then, 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 (approximately 10 to 15% per step) over approximately 30 minutes to a target value of less than 30 mbar.Once the pressure in the reaction vessel stabilizes at 28 mbar, the medium is allowed to react at 170 °C for an additional 4 h. During this polycondensation step, the stirring speed is maintained at 80 rpm. The produced PGS 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 h before analysis. [Table 3].

[0203] 2. Results

[0204] 2.1. Formulations tested

[0205] The compositions studied are presented below. The contents are expressed in pce (parts per cent of polymer, i.e. glycerol polyester and aliphatic dicarboxylic acid).

[0206] 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 polycarboxylic 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. The reference mixture has an Mn = 2656 g / mol and an Mw = 16520 g / mol. [Table 4]

[0207] 2.2. Protocol for the preparation of crosslinked polyesters

[0208] Step a)

[0209] Place a 100mL beaker on a heating plate equipped with a PT100 probe to control the temperature.

[0210] Introduce poly(glycerol sebacate)

[0211] Heat the polymer to 50°C while mixing it with a spatula. Mix the cyclic polycarboxylic anhydride with the poly(glycerol sebacate) with a spatula until a homogeneous mixture is obtained.

[0212] Cool to room temperature.

[0213] Step b): crosslinking

[0214] Place the mixture in the middle of a 2mm thick mold, between two silicone sheets 15g of the desired formulation.

[0215] Pressing on a platen at 140°C (no humidity control)

[0216] Crosslink the materials for time t C h desired and previously determined according to the method of measuring the crosslinking kinetics described in point 1. The time tch applied is the time necessary for the elastic modulus to reach the value of 1MPa, according to the method of measuring the crosslinking kinetics.

[0217] Cool to room temperature. Unmold and cut out the desired number of discs, 10 mm in diameter and 2 mm thick, using a cookie cutter.

[0218] 2.3. Characterization of crosslinked polyesters [Table 5]

[0219] 3. Discussion

[0220] It is noted that after 7 days of incubation, practically all the compositions according to the invention exhibit mass losses that are significantly to clearly higher compared to the reference composition.

[0221] Furthermore, it is noted that the use of cyclic polycarboxylic anhydride as a crosslinking agent makes it possible to significantly reduce the in vitro degradation time of a poly(glycerol sebacate) polymer in a PBS-type buffer at 37.5°C, while maintaining Shore A hardness values ​​similar to the reference PGS.

Claims

CLAIMS 1. Use of a cyclic carboxylic polyanhydride A, the cyclic carboxylic polyanhydride A comprising at least two cyclic carboxylic anhydride groups, and not comprising a linear carboxylic anhydride function, as a crosslinking agent for a glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid, so as to increase the bioresorbability and / or the degradation in aqueous medium of a glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a crosslinked dicarboxylic acid, in particular compared to a glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid thermally crosslinked in the absence of a crosslinking agent, and advantageously in the absence of cyclic carboxylic polyanhydride A.

2. Use according to claim 1, characterized in that 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)- ; -NR n R n - with R n and R n ' independently selected from H or a CrCs 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 devoid of linear anhydride groups.

3. Use according to any one of the preceding claims, characterized in that the cyclic polycarboxylic anhydride A comprises or consists of a compound of formula (I) or (II): in which • Li represents a bond; -O-; -S-; -S(O)-; -S(O)2-; -NR n Rn- with R n and R n ' independently selected from H or a C 1 -C 6 alkyl group; -C(O)-; or an aliphatic chain of 1 to 30 carbon atoms, in which from 1 to 6 methylene unit(s) is(are) optionally replaced by an arylene group, a group heteroarylene, -C(O)- ; -O- ; -S- ; -S(O)- ; -S(O)2- ; -NR m - with R m selected from H or a C 1 -C 6 alkyl group; -P-; -P(O)-; -SiR a Rb- with R a and Rb representing independently of one another a group -OH, C 1 -C 6 alkyl or C 1 -C 6 alkoxy, said aliphatic chain being substituted or unsubstituted by one or more, in particular one or two, C 1 -C 6 alkyl groups, C 1 -C 6 alkoxy, a hydroxyl, nitro, cyano, halogen atom, C 1 -C 6 haloalkyl, • 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 one another, a C1-C6 alkyl group, a hydroxyl, C1-C6 alkoxy, nitro, cyano, or a halogen atom, • n represents an integer ranging from 0 to 3, preferably from 0 to 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 ranging from 0 to 3, preferably from 0 to 2, • Ai represents: o A CC bond or a C=C bond connecting 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, and 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 chosen from a C1-C6 alkyl group, a hydroxyl, C1-C8 alkoxy, nitro, cyano, or halogen atom.

4. Use according to claim 3, characterized in that L1 represents a bond or an aliphatic chain of 1 to 6 carbon atoms, in which one or two methylene units is (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 a C1-C6 alkyl, C1-C6 alkoxy, or C1-C8 haloalkyl.

5. Use according to any one of the preceding claims, characterized in that the cyclic polycarboxylic anhydride A comprises or consists of a compound of formula (III) or (IV): in which 'I represents a single or double C-C bond, l_2 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 C-C alkyl group, a hydroxyl, C-C 1 alkoxy, nitro, cyano, or a halogen atom.

6. Crosslinked polyester obtained by crosslinking a glycerol polyester and an aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid with, as crosslinking agent, at least one cyclic carboxylic polyanhydride A as defined in any one of claims 1 to 5, with a loss of mass at 7 days after in vitro incubation at 37.5°C in a PBS buffer and drying at 60°C greater than or equal to 5%.

7. Crosslinked polyester according to claim 6, characterized in that the crosslinked polyester has a Shore A hardness measured according to standard ASTM D 2240:2021 at room temperature ranging from 20 to 80, typically from 20 to 50.

8. Crosslinked polyester according to claim 6 or 7, obtained by crosslinking: o 100 parts by weight of at least one polyester of glycerol and of an aliphatic monomer chosen from a dicarboxylic acid and a diester of a dicarboxylic acid, o from 10 to 100, preferably from 20 to 50 parts by weight of the cyclic polycarboxylic anhydride A.

9. Crosslinked polyester according to claim 8, in which the polyester of glycerol and of an aliphatic monomer selected from a dicarboxylic acid and a diester of a dicarboxylic acid carboxylic acid has a molar mass in number M n less than or equal to 10,000 g / mol.

10. Crosslinked polyester according to claim 8 or 9, in which the dicarboxylic acid monomer or the carboxylic diester monomer corresponds to the general formula R'OOC-(CH2) P -COOR', in which p represents an integer ranging from 1 to 30, preferably an integer ranging from 1 to 10, more preferably p=8, and R' represents H or each R' represents, independently of one another, a linear or branched alkyl, C1-C10, preferably C1-C4, more preferably methyl or ethyl.

Images