Photocrosslinkable copolyester compositions

Abstract

The present invention relates to a photocrosslinkable composition comprising a photocrosslinkable copolyester and a co-crosslinking agent of formula (I) below: (I) The present invention also relates to a method for photocrosslinking the photocrosslinkable composition, to a crosslinked composition obtained by crosslinking the photocrosslinkable composition, and to the use of said photocrosslinkable composition for the preparation of products by 3D printing.

Description

DESCRIPTION OF PHOTOCROSSABLE COPOLYESTER COMPOSITIONS SCOPE OF THE INVENTION The present invention relates to photocrosslinkable copolyester compositions, further comprising a co-crosslinking agent having unsaturated bonds. The present invention also relates to their preparation process and their use, particularly in crosslinking processes such as 3D printing processes, and the corresponding crosslinked copolyesters. STATE OF THE ART Biodegradable polyesters, such as polylactic acid (PLA), polyglycolic acid (PGA), and their copolymers, poly(glycerol sebacate) (PGS), are now ubiquitous in the preparation of biomaterials useful both as medical biomaterials and as surface coatings. Conventionally, PGS is produced by melt polycondensation of glycerol and a diacid at high temperature and under reduced pressure, with relatively long reaction times.However, with the development of 3D printing techniques, which require working at near-ambient temperatures, under atmospheric pressure, and preferably with short reaction times, new materials have been sought whose preparation processes are compatible with the requirements of 3D printing, while maintaining satisfactory thermo-mechanical properties. Similarly, conventional processes are also incompatible with the integration of temperature-sensitive organic molecules into the biomaterial. Thus, photocrosslinkable materials have been developed, obtained by copolymerizing glycerol with sebacic acid and unsaturated acids. The unsaturates can then be subjected to a photocrosslinking reaction, for example, under UV irradiation (see, in particular, WO2019 / 215441 and WO2021 / 078962).Other authors have turned to the use of itaconic acid (an unsaturated acid) as a comonomer. This comonomer is particularly interesting because, unlike (meth)acrylic acid derivatives, it is non-toxic and readily bioavailable, allowing the production of photocrosslinkable polymers usable for a wide range of applications, including biomedical ones, with a relatively low carbon footprint. For example, Rueben et al. (MRS Advances (2018), 3(27), 1551-1556) describe the synthesis of glycerol, sebacic acid, and itaconic acid decopolymers, but with particularly long preparation times (24 hours). Patent application CN11445635 also describes copolymers of polyols, dialiphatic acids, and itaconic acid, and in particular copolymers of glycerol, sebacic acid, and itaconic acid. However, the inventors demonstrated that the polycondensation preparation process of CN11445635 was not reproducible.Indeed, under the conditions described, uncontrolled side reactions (particularly crosslinking reactions) are observed, linked to the reactivity of the α,β-unsaturated double bonds of itaconic acid. These reactions induce heterogeneity in the functional copolymer and increase the viscosity of the resulting product to the point of clumping, rendering it unsuitable for use in applications such as coatings or in 3D printing processes. Therefore, there is a need for photocurable copolyester compositions with a simple, reliable, and reproducible preparation process, specifically adapted for industrial scale, thus avoiding the occurrence of uncontrolled side reactions.The use of specific crosslinking agents significantly reduces crosslinking times, making photocrosslinkable copolyester compositions usable in 3D printing processes, particularly at room temperature and atmospheric pressure. The monomers used are preferably non-toxic and bio-based to limit the carbon footprint of the resulting copolyesters. Furthermore, processing temperatures are generally lower than in conventional processes and are advantageously compatible with high-temperature sensitive organic molecules. BRIEF STATEMENT OF THE INVENTION Surprisingly, the inventors have demonstrated that adding a co-crosslinking agent of general formula (I) during the crosslinking of the photocrosslinkable copolyester improves the thermomechanical properties of the resulting crosslinked copolyester compared to copolyesters obtained without a co-crosslinking agent.This also allows for increased observed photocrosslinking rates and the use of preferably non-toxic and bio-based compounds, thus making them more environmentally friendly. The present invention therefore has as its first object a photocrosslinkable composition comprising: - a photocrosslinkable copolyester selected from (i) a copolyester whose constituent units are derived from the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, or (ii) a copolyester whose constituent units are derived from the polymerization of glycerol with a dicarboxylic acid monomer, said copolyester being subsequently functionalized with an acrylic monomer. the acrylic monomer being selected from itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, mesaconic anhydride, (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride, C1-C6 alkyl esters of (meth)acrylic acid, or a mixture thereof; - a co-crosslinking agent of the following general formula (I): in which X1 independently represents H or a group L1-R1, X2 independently represents H or a group L2-R2, X3 independently represents H or a group L3-R3, X4 independently represents H or a group L4-R4, X5 independently represents H or a group L5-R5, X6 independently represents H or a group L6-R6, each of L1, L2, L3, L4, L5 and L6 is independently absent or represents -C(O)- ; -S- ; -S(O)- ; -S(O)2- ; -NRa-;or a linear or branched, saturated or unsaturated but non-aromatic, divalent aliphatic chain of 1 to 10 carbon atoms, wherein 1 or more, in particular 1 to 4 methylene units (preferably non-adjacent), are optionally replaced by -C(O)-, -O-, -OC(O)-, -C(O)-O-, -NRb-C(O)-, -C(O)Rc-, -S-, -S(O)-, -S(O)2-, -NRd-, said aliphatic chain being optionally substituted by one or more aryl or ORe substituents, with Ra, Rb, Rc, Rd and Re independently representing H or a C1-alkyl group; C6, R1, R2, R3, R4, R5 and R6 independently representing H or a vinyl group of formula; with R representing H or a C1-C6 alkyl group, preferably H or a methyl group, at least two of the groups R1, R2, R3, R4, R5 and R6 representing a vinyl group, the vinyl group being linked by the bond to the group L1, L2, L3, L4, L5 or L6 respectively ,or directly to the oxygen atom when groups L1, L3 and / or L5 are absent, or to the rest of the molecule when L2, L4 and / or L6 are absent. The present invention also relates, as a second object, to a method for photocrosslinking a photocrosslinkable composition according to the invention, comprising a step of UV irradiation of the photocrosslinkable composition. The present invention also relates, as a third object, to a crosslinked composition obtained by crosslinking a photocrosslinkable composition according to the invention. The present invention also relates, as a fourth object, to the use of a photocrosslinkable composition according to the invention for the preparation of products by 3D printing. DETAILED DESCRIPTION OF THE INVENTION For the purposes of the present invention, the term “a” means “one or more” or “at least one”.For the purposes of this invention, a value range 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 value range designated by the expression "from a to b" represents the range of values ​​from a to b, i.e., including the strict limits a and b. "Approximately" in this description means that the value in question may be 10% lower or higher, in particular 5%, and especially 1%, than the stated value. The compounds mentioned in the description may be of fossil origin or bio-based. In the latter case, they may be partially or totally derived from biomass or obtained from renewable raw materials derived from biomass.Similarly, the compounds mentioned can also originate 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, dicarboxylic acid, and acrylic monomer. Glycerol is a triol with the following formula: . For the purposes of this invention, a "photocrosslinkable" polymer (including a copolyester) is defined as a polymer that, under the influence of light irradiation, and more particularly UV irradiation, undergoes crosslinking reactions, thereby modifying its chemical structure. These are generally radical reactions in the presence of a photoinitiator.For the purposes of this invention, "ambient temperature" means a temperature generally between 15°C and 40°C, preferably between 20°C and 30°C, and in particular around 25°C. "Atmospheric pressure" means a pressure of approximately 1 bar. "Aliphatic" means a linear, branched, and / or cyclic hydrocarbon group, whether saturated or unsaturated, but non-aromatic. A "divalent aliphatic chain" means a linear, branched, and / or cyclic divalent hydrocarbon group, whether saturated or unsaturated, but non-aromatic. Thus, an aliphatic chain includes substituted or unsubstituted, linear or branched alkylene (or alkanediyl), alkenylene (or alkeniyl), or alkynylene (cycloalkyndiyl) groups.The term "alkanediyl group" refers, for the purposes of this invention, to an acyclic, linear or branched, divalent hydrocarbon chain comprising from 1 to 10 carbon atoms, such as, for example, a methylene, ethanediyl, propanediyl, butanediyl, pentanediyl, or hexanediyl group. The term "alkenediyl group" refers, for the purposes of this invention, to an acyclic, linear, ouramized, divalent hydrocarbon chain comprising from 2 to 10 carbon atoms and at least one double bond, such as, for example, a vinylene (ethenylene) or propenylene group. The term "alkynediyl group" refers, for the purposes of this invention, to an acyclic, linear or branched, divalent hydrocarbon chain comprising from 2 to 10 carbon atoms and at least one triple bond.The term "C1-C6 alkyl group" here refers to a monovalent, saturated, linear or branched hydrocarbon chain comprising from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexyl groups. The term "(C2-C6) alkenyl group" in the context of this invention refers to a monovalent, linear or branched hydrocarbon chain comprising at least one double bond and comprising from 2 to 6 carbon atoms. Examples include ethenyl, propenyl, allyl, butenyl, pentenyl, and hexenyl groups. The term "(C3-C7)cycloalkyl" or "(C3-C7) cycloalkyl" refers, in the context of this invention, to a saturated cyclic hydrocarbon chain comprising 3 to 7 cyclic carbon atoms. A cycloalkyl may be monocyclic or bicyclic.For example, cyclopropyl, cyclopentyl, cyclohexyl, or cycloheptyl groups can be cited. An "aryl" group is understood to be an aromatic hydrocarbon group, preferably comprising 6 to 10 carbon atoms, and including one or more fused rings. As an example of a monovalent aromatic group, a phenyl or naphthyl group can be cited, advantageously phenyl. As used here, the "C=C double bond ratio" refers to the ratio of C=C double bonds contributed by at least one acrylic derivative or monomer in the polymer, expressed in mmol of double bonds / g of polymer obtained. The C=C double bond ratio is typically measured by carbon-13 nuclear magnetic resonance (NMR). 13 C). The C=C double bond ratio can also be obtained indirectly by quantifying the free acrylic derivative or monomer using size-exclusion chromatography (SEC). The percentage of acrylic derivative or monomer (or residual) is then measured. Assuming that the remaining acrylic derivative or monomer has reacted completely, the C=C double bond ratio corresponds to the difference between the amount of acrylic derivative or monomer involved in the reaction (or initial reaction) and the amount of free acrylic derivative or monomer, these amounts being expressed in mmol / g of polymer obtained. For the purposes of this invention, "halogen atom" or "halogen" means fluorine, chlorine, bromine, and iodine atoms. "Halide" means fluoride (F-), bromide (Br-), chloride (Cl-), and iodide (I-) ions.For the purposes of this invention, an "alkyl (C1-C6) group" is defined as a saturated, linear or branched monovalent hydrocarbon chain comprising 1 to 6, preferably 1 to 4, carbon atoms. Examples include methyl, ethyl, propyl, isopropyl, butyl, pentyl, and hexyl groups. An "alkoxy (C1-C6) group" is defined as a (C1-C6) alkyl group, as defined above, linked to the rest of the molecule via an oxygen atom. Examples include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, t-butoxy, n-pentoxy, and n-hexoxy groups. By "aryl," we mean here an aromatic hydrocarbon group, preferably comprising 6 to 10 carbon atoms, and including one or more fused rings, such as a phenyl or naphthyl group. Advantageously, it is phenyl.By "heteroaryl" we mean here an aromatic group comprising 5 to 10 cyclic atoms of which 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 cyclic atoms being carbon atoms. Examples of heteroaryl groups include furyl, thienyl, pyrrolyl, pyridinyl, imidazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyrazolyl, oxadiazolyl, thiadiazolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, quinolyl, isoquinolyl, quinoxalyl, and indyl. A "photoinitiator" is a compound that, when exposed to light, particularly UV light, produces a radical that initiates the photocrosslinking reaction, which is generally radical-mediated.As used here, a "stabilizing agent" means a compound that limits (or even eliminates) secondary reactions of the double bond of the itaconate function, such as radical reactions leading to uncontrolled cross-linking of the polymer, or Michael reactions. A phenol means an organic compound comprising a phenol function: substituted or unsubstituted, in particular by one or more substituents chosen from a halogen atom, -NO2, or a C1-C6 alkyl group, a C1-C6 alkoxy group, or a C1-C NH-alkyl group. 6. An aniline is understood to be an organic compound comprising a function aniline : with Rn representing H or a C1-C6 alkyl group, substituted or unsubstituted, in particular by one or more substituents chosen from a halogen atom, -NO2, or a C1-C6 alkyl group, C1-C6 alkoxy, C1-C6 NH-alkyl 6.1. Photocurable Composition The photocurable composition comprises: - a photocurable copolyester selected from (i) a copolyester whose constituent units are obtained by the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, or (ii) a copolyester whose constituent units are obtained by the polymerization of glycerol with a dicarboxylic acid monomer, said copolyester being subsequently functionalized with an acrylic monomer, the acrylic monomer being selected from itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, mesaconic anhydride, (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride, C1-C6 alkyl esters of (meth)acrylic acid, or a mixture thereof; - an agent co-crosslinking agent with the following general formula (I): in which X1 independently represents H or a group L1-R1, X2 independently represents H or a group L2-R2, X3 independently represents H or a group L3-R3, X4 independently represents H or a group L4-R4, X5 independently represents H or a group L5-R5, X6 independently represents H or a group L6-R6, each of L1, L2, L3, L4, L5 and L6 is independently absent or represents -C(O)- ;-S- ; -S(O)- ; -S(O)2- ; -NRa- ; or a linear or branched, saturated or unsaturated but non-aromatic, divalent aliphatic chain of 1 to 10 carbon atoms, wherein one or more, in particular one to four methylene units (preferably non-adjacent), are optionally replaced by -C(O)-, -O-, -OC(O)-, -C(O)-O-, -NRb-C(O)-, -C(O)Rc-, -S-, -S(O)-, -S(O)2-, -NRd-, said aliphatic chain being optionally substituted by one or more aryl or OR substituents e , with R a , R b , R c , R d and R eindependently representing H or an alkyl group in C1-C6, R1, R2, R3, R4, R5 and R6 independently represent H or a vinyl group of formula with R representing H or a C1-C6 alkyl, preferably H or a methyl, at least two of the groups R1, R2, R3, R4, R5 and R6 representing a vinyl group, the vinyl group being linked by bonding to the L1, L2, L3, L4, L5 or L6 group respectively, or directly to the oxygen atom when the L1, L3 and / or L5 groups are absent, or to the rest of the molecule when L2, L4 and / or L6 are absent. The dicarboxylic acid monomer can be aliphatic, aromatic, or aliphatic / aromatic. The dicarboxylic acid monomer cannot be itaconic acid. An aliphatic / aromatic dicarboxylic acid monomer comprises an aliphatic portion and an aromatic portion. The dicarboxylic acid monomer preferably comprises from 3 to 36 carbon atoms. According to preferred embodiments of the invention, the dicarboxylic acid monomer is aliphatic, in particular saturated, especially linear or branched, preferably a (C3-C20)alkanediyldiacid carboxylic acid, more preferably a (C8-C15)alkanediyldiacid carboxylic acid. A (Cx-Cy)alkanediyl group is a divalent, saturated, linear or branched hydrocarbon group comprising from x to y carbon atoms. Preferably, the dicarboxylic acid monomer comprises or consists of a compound of formula [HOOC-(CH2)n-COOH], in which n is an integer from 1 to 30, preferably an integer from 1 to 10.Advantageously, this is sebacic acid (n=8). The acrylic monomer is preferably chosen from (meth)acrylic acid, (meth)acrylic anhydride, itaconic acid and itaconic anhydride, or a mixture thereof. Preferably (meth)acrylic anhydride, itaconic acid and itaconic anhydride, or a mixture thereof. The photocrosslinkable copolyester has a C=C double bond ratio greater than or equal to 0.004 mmol / g, preferably greater than or equal to 0.04 mmol / g or 0.1 mmol / g, advantageously greater than or equal to 0.5 mmol / g, more preferably greater than or equal to 1 mmol / g.The photocrosslinkable copolyester may also exhibit at least one of the following characteristics:^ its number-average molar mass (Mn) is greater than or equal to 500 g / mol, in particular greater than or equal to 1000 g / mol, advantageously greater than or equal to 1500 g / mol, preferably greater than or equal to 2000 g / mol;^ its number-average molar mass (Mn) is less than 10,000 g / mol, in particular less than or equal to 3500 g / mol, preferably less than or equal to 3000 g / mol;^ its dispersity Đ (Mw / Mn) is less than 10, preferably less than or equal to 8, in particular less than or equal to 6. The number-average molar mass (Mn), the mass-average molar mass (Mw), and the dispersity (also called polydispersity, dispersity Đ, which is the ratio Mw / Mn) may be measured in a known by SEC analysis, specifically as described below. The residual monomer content and the (1,2,3-triacylglyceride) unit content are measured using a known method by NMR. 1H, possibly combined with 2D HSQC / HMBC and NMR experiments 13C, as described below. Advantageously, the photocurable composition comprises from 10 to 95%, in particular from 20 to 90%, preferably from 50% to 85% by weight of photocurable copolyester, relative to the total weight of the composition.Typically, when the photocrosslinkable copolyester is a copolyester whose constituent units are obtained from the polymerization of glycerol with a dicarboxylic acid monomer, said copolyester being subsequently functionalized with an acrylic monomer, it is likely to be obtained by a process comprising the following steps: a) Contacting a copolyester of glycerol and an unfunctionalized dicarboxylic acid monomer with an acrylic monomer selected from itaconic acid, itaconic anhydride, (meth)acrylic acid, C1-C6 alkyl esters of (meth)acrylic acid, and mixtures thereof, b) Heating the mixture from step a) in the presence of a stabilizing agent for a time sufficient to form a photocrosslinkable functionalized copolyester, c) Cooling and recovery of the photocrosslinkable functionalized copolyester. The copolyester of glycerol and a dicarboxylic acid monomer (unfunctionalized) can be obtained, in particular, by implementing the processes described in EP3149067 and EP1448656. The copolyester of glycerol and an unfunctionalized dicarboxylic acid monomer advantageously has one or more of the following characteristics: - a number-average molar mass (Mn) of the unfunctionalized copolyester greater than or equal to 500 g / mol, preferably greater than or equal to 1000 g / mol, even more preferably greater than or equal to 1500 g / mol, advantageously greater than or equal to 2000 g / mol ;- an average number molar mass (Mn) of the unfunctionalized copolyester less than or equal to 10000 g / mol, preferably less than or equal to 3500 g / mol, preferably less than or equal to 3000 g / mol; - a dispersity Đ (Mw / Mn) of the unfunctionalized copolyester less than 10, preferably less than or equal to 8; - a residual monomer content less than or equal to 5% by weight of the unfunctionalized copolyester; - a (1,2,3-triacylglyceride) unit content less than or equal to 20 mol% relative to all units of the unfunctionalized copolyester; - a molar ratio of the (1,3-diacylglyceride) unit to the (1,2-diacylglyceride) unit greater than 1 of the unfunctionalized copolyester. The residual monomer content and the (1,2,3-triacylglyceride) unit content are measured using a known method by NMR. 13 C, where appropriate combined with 2D HSQC / HMBC and NMR experiments 13C, as described later. The copolyester of glycerol and a dicarboxylic acid monomer can also be characterized by its free hydroxyl content, or the number of free hydroxyl groups per gram of copolyester. The free hydroxyl content is determined by NMR, typically NMR 13 C, and is expressed in mol / g of copolyester. For example, the hydroxyl number, expressed in mg KOH / g of copolyester, can be measured using the method in ASTM E222-23. The ASTM E222-23 method involves acetylating the hydroxyl groups present with acetic anhydride and then titrating with KOH. The hydroxyl number is then easily converted by those skilled in the art into mmol of free OH / g of copolyester. Advantageously, the molar ratio of acrylic monomer / N OHThe ratio varies from 1:100 to 2:1, particularly from 1:1 to 2:1. Step (a), contacting the unfunctionalized copolyester with an acrylic monomer, is typically carried out at a temperature between 20°C and 200°C. In some embodiments, the contacting in step (a) is carried out in the absence of solvent or diluent. Alternatively, in step (a), the unfunctionalized copolyester and the acrylic monomer can be contacted in a solvent, such as water. Typically, water is added in a mass fraction ranging from 0% to 100%, preferably from 5% to 50%, and even more preferably from 10% to 40%, relative to the mass of unfunctionalized copolyester and acrylic monomer involved. To promote homogenization of the medium, stirring can be carried out in a known manner. The stabilizing agent can also be added in step (a). In step (b), the functionalization reaction involves the esterification of a free alcohol group from the glycerol copolyester and a dicarboxylic acid monomer by the acrylic monomer. Depending on the reaction conditions, transesterification reactions may also occur, but these are generally minor.According to one variant, the functionalization step is carried out under conditions that allow water to be removed from the reaction medium (or reactor). Removing water as it is formed during functionalization has several advantages: it improves the reaction yield and accelerates its kinetics. Preferably, the recovered water is recycled as a solvent for the contacting step (a). The pressure in the reactor during step (b) can be constant or variable. The functionalization step (b) is preferably carried out at a pressure between 0.0001 and 2 bar, typically less than or equal to 30 mbar, in particular less than or equal to 20 mbar, preferably less than or equal to 10 mbar. Any method known to those skilled in the art can be used to lower the pressure, in particular by means of a pump (especially a vane pump), a diaphragm pump, a rotary pump, etc.Such an intermediate pressure is less than 1 bar and varies, for example, from 800 mbar to 50 mbar. The heating step (b) is preferably carried out at a temperature between 20°C and 250°C. The temperature of the heating step (b) may be variable or constant. The temperature is preferably reached by applying an isotherm or a heating ramp. The heating ramp may include one or more plateaus, also called temperature holding periods, and the ramp typically has a slope of between +0.1°C / min and +1°C / min. In one embodiment, the heating step (b) is carried out in the presence of a catalyst, in particular at a concentration of 5000 ppm or less, preferably 3000 ppm or less, advantageously 2000 ppm or less, relative to the total mass of unfunctionalized copolyester and acrylic monomer involved.Preferably, the catalyst comprises or consists of a food-grade catalyst, that is, a catalyst suitable for food contact (for animals and humans) that meets requirements guaranteeing there is no risk of toxicity induced by this catalyst for the polyester produced. Such a catalyst. The catalyst meets, in particular, the requirements of US standards 21 CFR 175.300, 21 CFR 177.2420, and / or 21 CFR 175.105 in effect at the filing date. The food-grade catalyst is advantageously tin-based, specifically monobutyltin oxide marketed under the name FASCAT 9100 by PMC Organometallix. Advantageously, the heating in step b) is carried out for 30 minutes to 12 hours, preferably for 1 to 5 hours. Step c) of cooling is carried out in a manner known to those skilled in the art. Alternatively, when the photocrosslinkable copolyester is a copolyester whose constituent units are obtained from the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, it is likely to be obtained by a process comprising a polycondensation step of glycerol with a dicarboxylic acid monomer and at least one acrylic monomer as defined herein.The acrylic monomer can be added at the same time as the glycerol and the dicarboxylic acid monomer, or in a subsequent step. Typically, the process comprises: a') a step of contacting the glycerol with the dicarboxylic acid monomer and at least one acrylic monomer, and the stabilizing agent, and b') a polycondensation step under reduced pressure, the pressure typically being less than or equal to 30 mbar, in particular less than or equal to 20 mbar, preferably less than or equal to 10 mbar, and preferably at a temperature between 110°C and 200°C, preferably between 120°C and 180°C, in particular at 130°C.According to another embodiment, the process comprises: a'') a step of contacting glycerol with dicarboxylic acid monomer, b'') a first polycondensation step of glycerol with the dicarboxylic acid monomer to obtain a mixture comprising poly(glycerol dicarboxylate), at a pressure between 1 and 2 bar, c'') a step of contacting the mixture comprising poly(glycerol dicarboxylate) with at least one acrylic monomer and the stabilizing agent, and d'') a second polycondensation step in the presence of the stabilizing agent under reduced pressure, the pressure typically being less than or equal to 30 mbar, in particular less than or equal to 20 mbar, preferably less than or equal to 10 mbar, to form the photocrosslinkable copolyester. The polycondensation step is preferably carried out at a temperature between 50°C and 250°C, preferably between 100°C and 200°C, especially between 120°C and 190°C.The target temperature for the polycondensation step d'') can be between 110°C and. 200°C, preferably between 120°C and 180°C. The temperature is preferably reached by applying an isotherm or a heating ramp. The heating ramp may include one or more plateaus, also called temperature holding periods, and typically has a slope of between +0.1°C / min and +1°C / min. Working under reduced pressure during the polycondensation steps improves the efficiency and kinetics of the corresponding polycondensation step. Steps (a') and (a''), which involve contacting the glycerol with the dicarboxylic acid monomer and possibly at least one acrylic monomer, are typically carried out at a temperature between 20°C and 100°C. During step (a') or (a''), the glycerol and dicarboxylic acid monomers may be contacted in water. Adding water to the monomer mixture allows for homogenization of the mixture and thus reduces its overall viscosity.To promote this homogenization, agitation can be implemented in a known manner. According to these variations, water is added to the monomers in an amount by mass ranging from 0% to 100% relative to the mass of the monomers involved, preferably from 5% to 50% relative to the mass of the monomers involved, and even more preferably from 10% to 25% relative to the mass of the monomers involved. According to other particularly preferred variations, the contacting of the monomers is carried out by introducing the dicarboxylic acid monomer – and optionally at least one acrylic monomer – into a mixture comprising glycerol and water, improving the homogenization of the reaction mixture after the addition of the dicarboxylic acid monomer and optionally at least one acrylic monomer.According to one variant, step (c'') of contacting the mixture comprising poly(glycerol dicarboxylate) with at least one acrylic monomer includes adding at least one acrylic monomer, and optionally the stabilizing agent, to the mixture heated to a temperature between 50°C and 250°C, preferably between 100°C and 200°C, in particular between 120°C and 190°C. Preferably, during the contacting step (c'), the temperature can vary from room temperature to 130°C. Preferably, the stabilizing agent does not react with the double bond of the acrylic derivative or monomer in significant yields, or reacts reversibly. For example, the stabilizing agent may undergo a reversible Michael addition reaction. It is therefore a nucleophilic compound with low reactivity towards the crosslinking agent such as a phenol or aniline. Advantageously, the stabilizing agent is a compound with the general formula: in which Z represents O or NR q with R q representing H or alkyl in C1-C6, R x1 represents H, -CO-aryl or -CO-heteroaryl, R x2Rx2 independently represents H, halogen, -NO2, -OH, C1-C6 alkoxy, -COOH, C1-C6 -COO-alkyl, C1-C6 NH-alkyl, -SRs, or a C1-C6 alkyl optionally substituted with ORS or SRS. Rs independently represents a C1-C8 alkyl, and p is an integer from 1 to 4, preferably 1 or 2. Preferably, p is 1 or 2, and Rx2 independently represents H, -OH, -COOH, a C1-C6 alkyl optionally substituted with a C1-C6 alkoxy, or SRS, in which RS is as defined above. Advantageously, Rx1 represents H or -CO-phenyl. The stabilizing agent may be used alone or in mixtures. Typically, these include aniline, phenol, methoxyphenol (especially 4-methoxyphenol or guaiacol), syringol, 4,6-bis(octylthiomethyl)-o-cresol and / or 2-hydroxy-4-methoxybenzophenone.The amount of stabilizing agent introduced is advantageously between 0.01% and 5% by mass relative to the total mass of the monomers and, if applicable, the acrylic monomer, preferably between 0.1% and 2%, and preferably between 0.5% and 1.6%. Preferably, the molar ratio of acrylic monomer to dicarboxylic acid monomer varies from 1 / 99 to 99 / 1, preferably from 10 / 90 to 90 / 10, and advantageously from 20 / 80 to 80 / 20. Co-crosslinking agent Preferably, each of L1, L2, L3, L4, L5 and L6 is independently absent or represents a -C(O)- group or a linear or branched, saturated or unsaturated but non-aromatic, divalent aliphatic chain of 1 to 10 carbon atoms, in which 1 or more, in particular 1 to 4 methylene unit(s) are optionally replaced by -C(O)-, -O-, -OC(O)-, -C(O)-O-, said aliphatic chain being optionally substituted by aryl or OR substituents. e with R e chosen from H or an alkyl group in C1-C6. Advantageously, R2, R4, and R6 represent H and R1, R3, and R5 independently represent H or a vinyl group of formula as defined above, provided that at least two groups among R1, R3, and R5 are a vinyl group. Preferably, R2, R4, and R6 represent H and R1, R3, and R5 independently represent a vinyl group of formula defined above. Advantageously, X2, X4 and X6 represent H. Preferably, the co-crosslinking agent is chosen from the group consisting of compounds with general formulas (Ia), (Ib), (Ic), and (Id): in which R, R' and R'' independently represent H or a C1-C6 alkyl, preferably H or a methyl, and n1, n3, n5, m1, m3, m5 independently represent an integer from 1 to 6, preferably 1 or 2, the co-crosslinking agent being advantageously chosen from the group consisting of Advantageously, the co-crosslinking agent is present at a concentration ranging from 5% to 90%, in particular from 10% to 80%, preferably from 15% to 50%, by mass relative to the total mass of the composition. Additives: The composition may further comprise a photoinitiator, advantageously at a concentration ranging from 0.05% to 5%, preferably from 0.1% to 4%, in particular from 0.2% to 3%, by mass relative to the total mass of the composition. Photoinitiators suitable for photocrosslinking are well known to those skilled in the art. They may be of type I or type II. Type I photoinitiators are single-molecular systems that proceed by homolytic cleavage of a C-C bond, in particular by Norrish I cleavage.The molecules involved are generally aromatic ketones which, after light absorption, undergo homolytic cleavage of the bond at the α position relative to the carbonyl group (Norrish I type cleavage) from their excited triplet state, which leads to the formation of two free radicals capable of initiating a radical polymerization reaction (see in particular Ley et al. 14th International Francophone Colloquium on Optical Methods and Techniques for Industry / 16th French Congress of the FLUVISU / SFO Club (CMOI-FLUVISU 2015), CMOI Club – French Optical Society, Nov 2015, Pleumeur-Bodou, France. pp.124-129. hal-01583762). Type I photoinitiators are in particular any precursor of a benzoyl radical: Type II photoinitiators are, in particular, any precursor of a cetyl radical (inert) and with a radical precursor (an amine). The photoinitiators will be chosen in particular from the type I photoinitiator family. Examples include 2,4,6-Trimethylbenzoyldi-Phenylphosphinate (TPO L), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and 1-Hydroxycyclohexyl phenyl ketone (HCHPK). Advantageously, the composition further comprises a compound M, liquid at room temperature, comprising a radical polymerizable function, this radical polymerizable function preferably being an acrylic function, typically of the formula representing H or a C(O)ORf group, and with Rf representing H, or a C1-C10 alkyl group, the alkyl group being unsubstituted or substituted by one or more, preferably one or two, C1-C6 alkoxy, C2-C6 alkenyl, NRp1Rp2 or NRp1Rp2Rp3 groups +X-, with Rp1, Rp2, and Rp3 independently representing H or a C1-C6 alkyl group and X- representing a negatively charged counterion such as a halide, hydrogen sulfate (HSO4-), or bisulfite (HSO3-), the acrylic group being linked to the rest of the molecule by the bond. Advantageously, compound M further comprises one or more advantageously chosen functional groups from: An amine function, in particular a -NRn1Rn2 or -NRn1Rn2Rn3+ group; X-, with Rn1, R n2 and R n3independently representing H or a C1-C6 alkyl group and X- representing a negatively charged counterion such as a halide, hydrogen sulfate (HSO4-) or bisulfite (HSO3-), ^A carboxylic acid or carboxylic ester function. Preferably the molar mass of compound M is less than or equal to 300 g / mol, in particular less than or equal to 250 g / mol. Advantageously, the monomer M is an unsaturated alpha-beta ester optionally substituted with a second ester function, such as itaconic acid, itaconic anhydride, (meth)acrylic acid, or a derivative thereof, or mixtures thereof. Advantageously, compound M is a compound of formula (II), (III), (IV) or (V): in which R represents H or a C1-C6 alkyl, preferably H or a methyl, R f and R f’ independently represent H, a C1-C alkyl 10 , the alkyl group at C1- C 10being unsubstituted or substituted by one or more, preferably one or two, alkoxy group(s) at C1-C6, alkenyl group(s) at C2-C6, NR n1 R n2 or NR n1 R n2 R n3 + X-, with R n1 , R n2 and R n3independently representing H or a C1-C6 alkyl group and X- representing a negatively charged counterion such as a halide, hydrogen sulfate (HSO4-), or bisulfite (HSO3-). Preferably, compound M is a C1-C6 alkyl diester of itaconic acid or a C1-C10 alkyl ester of methacrylic acid. Examples of compound M include dimethyl itaconic acid, butyl methacrylate, and 2-ethylhexyl methacrylate. Typically, compound M is present in a concentration ranging from 1% to 90%, in particular from 10% to 80%, preferably from 30% to 70%, by mass relative to the total mass of the composition. In some embodiments, the composition does not include any additives, in particular no conventional additives. According to embodiments, the photocurable composition may further comprise one or more conventional additives in the art, such as fillers.The composition may also include an additive chosen from the group consisting of colourants, stabilizers, organic fillers and mixtures thereof. advantageously at a content ranging from 1% to 50% by mass relative to the total mass of the composition. The colorants and organic fillers are well known to those skilled in the art. The stabilizing agents are typically as defined previously. According to some embodiments, the photocurable composition may include a molecule of interest. The photocurable composition can be obtained by simply mixing the different components, preferably at room temperature to avoid any unwanted or secondary reactions. In particular, the photoinitiator is preferably added to the photocurable composition at room temperature. This avoids any undesirable crosslinking reaction. 2.Photocrosslinking Process: The invention also relates to a photocrosslinking process for the photocrosslinkable composition described herein, comprising a UV irradiation step of the photocrosslinkable composition or the photocrosslinkable copolyester, preferably in the presence of a photoinitiator. Advantageously, the irradiation is carried out at a temperature ranging from 0°C to 200°C, in particular from 5°C to 150°C, preferably from 10°C to 100°C. The irradiation is typically carried out at atmospheric pressure. It can be performed under air or under an inert atmosphere, in particular under N2 scanning. Preferably, the irradiation is carried out at a wavelength ranging from 250 nm to 500 nm, preferably from 300 to 450 nm, even more preferably from 350 to 400 nm, in particular 365 nm. A person skilled in the art will know how to adapt the irradiation power, in particular according to the wavelength and the distance of the wave source to the composition to be irradiated.The irradiation time typically varies from 0.1 s to 240 minutes, particularly from 1 s to 180 minutes. Advantageously, the photoinitiator is present at a concentration of 5% or less by mass, and more preferably at 1% or less by mass, relative to the total mass of the photocurable composition. The photoinitiators are as defined above. 3. Uses of the Photocurable Composition The photocurable composition according to the invention is useful for preparing products by 3D printing. Examples of such products include patches for diffusing active ingredients, implants, particles (including micro- and macroparticles), coatings, fibers and threads, etc. Indeed, during 3D printing, the photocurable composition undergoes crosslinking. Specifically, 3D printing includes a focused irradiation step in a bath containing the photocurable composition, to form the products layer by layer by photocrosslinking. Alternatively, during 3D printing, the photocurable composition can be crosslinked by thermal crosslinking. The invention therefore also relates to the use of the photocurable composition for the preparation of products by 3D printing, preferably by 3D printing using photocrosslinking.Examples of such technologies include stereolithography (SLA), Digital Light Processing (DLP), Continuous Liquid Interface Production (CLIP), Daylight Polymer Printing (DPP), and Film Transfer Imaging (FTI). 4. Photocured Composition The invention also relates to a crosslinked composition obtained by crosslinking, in particular thermal crosslinking and / or photocrosslinking, of the photocurable composition according to the invention. According to one embodiment, the crosslinked composition can be obtained by the photocrosslinking process described above.According to another variant, the crosslinked composition can be obtained by thermal crosslinking, particularly with thermal initiation optionally in the presence of initiators chosen from among the producers of radicals by thermal decomposition, such as peroxides, like cumene hydroperoxide, or azo compounds, such as azobiisobutyronitrile (AIBN), in dispersed or non-dispersed media. The photocrosslinked composition advantageously has a storage modulus G' at 37°C and 10 Hz ranging from 0.05 to 10 MPa and preferably from 0.2 to 2 MPa. METHODS Structural analysis: NMR Structural analysis, as well as the determination of the C=C double bond ratio and the proportion of unreacted anhydride or itaconic acid (residuals) present in the polymer, are carried out by NMR analysis. The spectra were acquired on a BRUKER Avance III 600 MHz spectrometer equipped with a 5mm BBFO-zgrad "broadband" probe. The NMR experiment. 1Quantitative H uses a simple 30° pulse sequence and a 3-second repetition delay between each of the 64 acquisitions. The samples are solubilized in a deuterated solvent, deuterated acetone (acetone d 6Unless otherwise indicated, 1H NMR spectroscopy coupled with 2D HSQC / HMBC and 13C NMR spectroscopy allows for the quantification of the microstructure of different polyesters (see allocation tables). Macrostructure analysis: SEC. The SEC (Size Exclusion Chromatography) technique separates macromolecules in solution according to their size using columns filled with a porous gel. Macromolecules are separated according to their hydrodynamic volume, with the largest eluting first. While not an absolute method, SEC allows for the determination of the molar mass distribution of a polymer. Using commercial standard products, the various number-average (Mn) and weight-average (Mw) molar masses can be determined, and the polydispersity index (Đ = Mw / Mn), also called "dispersity," can be calculated.The macrostructure of the copolyesters was analyzed by size-exclusion chromatography with differential scanning calibration (SEC RI), using low-weight polystyrene (PS) calibration with medium-weight standards. Samples were dissolved at a concentration of approximately 1 g / L in butylated hydroxytoluene (BHT)-free THF, then stirred for two hours before injection. The analysis temperature was 35°C, with a mobile phase flow rate of 1 mL / minute on Agilent 2 Mixed E + 2 Mixed 2 columns. Structural analysis: MIR. Kinetic monitoring of photocrosslinking was performed using a mid-infrared (MIR) spectrometer with wavelengths between 4000 and 650 cm⁻¹ (Vertex 70 model, commercially available from Bruker), equipped with a germanium crystal on a Vertex 70-3 spectrometer with an MCT detector. A scan count (Ns) of 32 is used. The spectrometer was equipped with a 365nm UV LED lamp with a power of 9mW / cm². 2irradiating at a distance of 5 cm from the sample. Crosslinking is monitored by tracking the disappearance of the C=C band of itaconate at 1638 cm⁻¹ -1 depending on the UV irradiation time (measurement of the peak area of ​​the band at 1638cm²) -1Mechanical property measurement: storage modulus G'. The mechanical properties are measured on an Anton Paar MCR302 rheometer, equipped with a 20 mm diameter plane-plane geometry. The measurements are performed on a cylindrical sample 2 mm thick and 2 cm in diameter, obtained by molding in a metal mold followed by curing for 1 hour under a UV LED lamp (365 nm LED, 9 Mw / cm²) at room temperature. This sample is subjected to a frequency sweep from 0.1 to 100 Hz under sinusoidal shear loading at 0.1% strain, at a temperature of 37°C. The resulting stress is measured. The results used are the storage modulus (G') at 37°C and 10 Hz, expressed in megapascals (MPa). The moduli G*, G', and G'' are calculated according to the equations below: ^ avec :^ σ the measured stress (in MPa) and ε the strain imposed on the sample (in %).^ G', the real part of G*, called the storage modulus (in MPa), which characterizes the stiffness of the viscoelastic material. G' characterizes the elastic behavior (the energy conserved and fully released by the material);^ i, the "imaginary" unit (i2 = -1);^ G'', the imaginary part of G*, called the loss modulus or dissipation modulus (in MPa), which characterizes the viscous behavior (the energy dissipated as heat). EXAMPLES The following examples are given by way of illustration, but shall in no way be considered as limiting the present invention. I.Synthesis of Photocrosslinkable Copolyesters Example 1: Synthesis of an unfunctionalized glycerol-co-sebacate copolyester, denoted PGS. In a 500 mL double-jacketed reactor fitted with a distillation column, a condenser, and a distillate recovery trap, glycerol (1 molar equivalent) and sebacic acid (1 molar equivalent) are added under a nitrogen flow. The reactor is then gradually heated to 130 °C with stirring and nitrogen. Once the temperature reaches 130 °C, the reaction is allowed to proceed for 24 hours under atmospheric pressure and a nitrogen flow. At 130 °C, water is continuously removed. When the conversion exceeds 80%, as measured by the amount of water produced, the reaction is stopped. The resulting PGS is collected as a white paste after cooling to room temperature. It has a number molar mass of about 1852 g / mol, a mass molar mass Mw of about 5067 g / mol, a dispersity of about Δ = 2.7, and a free hydroxyl content of 5 mmol / g. Example 2: Synthesis of photocrosslinkable copolyesters according to the invention: itaconate-grafted glycerol-co-sebacate copolyester. Hereafter, PGS-IA will be denoted as an itaconate-grafted glycerol-co-sebacate copolyester obtained with itaconic acid as the acrylic monomer. In a 500 mL double-jacketed reactor fitted with a distillation column, a condenser, and a distillate recovery trap, under nitrogen flow, the PGS of Example 1, the acrylic monomer (0.4 molar equivalents relative to the 1,3-diacylglyceride motifs of the PGS of Example 1 (major motif)), and 4-methoxyphenol as a stabilizing agent (1.56% by mass relative to the total mass of the mixture including the stabilizing agent) are added. The reactor is then heated to 130°C (or 80°C or 140°C) gradually under agitation and nitrogen.Once the temperature of 130°C (or 80°C or 140°C) is reached in the medium, the reaction is left under atmospheric pressure and nitrogen flow, at 130°C (or 140°C), with water continuously removed for the reaction time indicated in Table 1. A light yellow viscous liquid is obtained, corresponding to PGS-IA, and is then cooled to room temperature. The processes of tests 2.1 to 2.4 are carried out without solvents. The reaction conditions of the different examples are summarized in Table 1. The polyester PGS functionalized with methacrylic anhydride, denoted PGS-MA, was synthesized according to the procedure of the publication Hybrid manufacturing strategies for tissue engineering scaffolds using methacrylate functionalized poly(glycerol sebacate), S.Pashneh-Tala, R.Moorehead, F.Claeyssens. Journal of Biomaterials Applications, Volume 4, issue 8, pp.1114–1130, 2020. [TABLE 1] T. est 2.1 Test 2.2Itaconic monomer Itaconic acid Methacrylic anhydride Heating step duration 3h45 25h30 Target temperature 130°C 24°C Pressure Atm. Atm. Appearance of PGS-IA or PGS-MA viscous yellow liquid Viscous white liquid obtained after cooling orange Table 2: Results of NMR analyses (acetone d6) of PGS-IA or PGS-MA obtained in tests 2.1 to 2.2 [TABLE 2] Test 2.1 Test 2.2 Structural characterization of the photocrosslinkable copolyester molar % of 1-acylglyceride / polymer ≈ 2.8 ≈ 1 molar % of 2-acylglyceride / polymer ≈ 0.5 1.2% molaire of 1.2- ≈ 3,7 ≈ 5 diacylglyceride / polymer % molaire of 1.3- ≈ 6,8 ≈ 21 diacylglyceride / polymer molar % of 1, 2, 3-5 ,5 ≈ 10 triacylglyceride / polymer % molar of itaconic monomer or 1 0,3 ≈ 32 grafted methacrylic / polymer Presence of free monomers or reagents %molar of free glycerol ≈ 0.4 Not detected %molar of itaconic monomer or ≈ 19,9 ≈ 16Free methacrylic acid Quantity of OH in the product ≈3.3 Not determined (mmol / g) Quantity of unsaturates in the product or double bond ratio ≈ 2.1 Not determined C=C* (mmol / g) *Takes into account the unsaturates of the free and grafted itaconic acid or anhydride Table 3: Calculation of the average number (Mn) and mass (Mw) molar masses and dispersity by SEC analysis (dissolution in THF, poly(styrene) standard) of PGS-IA or PGS-MA obtained in tests 2.1 to 2.2. [TABLE 3] Mn (g / mol) Mw (g / mol) Dispersity, ΔTest 2.1 2271 29113 12.8Test 2.2 1955 7515 3.8II - Synthesis of agents Co-crosslinking agent of formula (I) Example 3.1: Preparation of 1,3,5-triyl tris(pent-4-enoate)benzene, denoted Flo-Vinylester, of formula Synthesis: 5 g (0.04 mol; 1 equivalent) of phloroglucinol are introduced into a three-necked flask. The phloroglucinol is then degassed under an inert atmosphere. Next, 96 mL of dichloromethane, previously degassed with nitrogen (N2), are introduced into the three-necked flask containing the phloroglucinol under nitrogen. The mixture is stirred (500 rpm) under nitrogen. A white suspension is obtained. The mixture is cooled to 2°C. 14.5 g of 4-pentanoyl chloride (0.12 mol; 3.05 equivalents) are then introduced into the mixture. Finally, 12.8 g (0.13 mol; 3.2 equivalents) of triethylamine are added dropwise to the mixture (addition time approximately 15 minutes). A color change is observed, from white to yellow to orange, then to light brown, concomitantly with the formation of a brown / orange suspension. The ice bath is removed and the reaction mixture is kept under stirring, at room temperature and under nitrogen, overnight.The reaction is stopped by adding 146 mL of distilled water. The appearance of two liquid phases and the disappearance of the suspension are observed. After 30 minutes of stirring at room temperature, the brown organic phase is recovered (pH aqueous phase: 6) and washed with 2 x 50 mL of distilled water (pH aqueous phase: 6). The organic phase is evaporated under reduced pressure. 19.47 g of crude product in the form of brown oil are obtained (NMR purity, CDCl3: 54%). massiquePurification: 19 g of crude product are dissolved in 58 mL of a petroleum ether / ethyl acetate mixture (v / v: 1 / 1). The resulting solution is then purified on silica gel (0.04–0.063 cm, silica height 2 cm, silica mass: 15.57 g) using 3 x 60 mL of a petroleum ether / ethyl acetate mixture (1 / 1) as the eluent. The filtrate is collected and evaporated under reduced pressure. 10.29 g of a yellow oil are obtained (NMR purity, CDCl3: 65 wt.). 1 wt. of 4-methoxyphenol can be added to the product obtained before the evaporation step to stabilize it. Example 3.2: Preparation of FLO-MA. The compound named FLO-MA has the formula is synthesized according to the synthesis protocol described in patent application US20200317870, in particular in Figure 7 and paragraph

[0116] III - Photocurable Composition According to the Invention Example 4: Preparation of a photocurable composition according to the invention The polymer of Example 2 is mixed with other compounds as follows (mass percentages are expressed relative to the total mass of the composition):^ 36 to 100% by mass of a photocurable copolyester of Example 2,^ 0 to 19% by mass of a co-crosslinking agent FLO-Vinyl ester and / or FLO-MA,^ 0 to 35% by mass of 2-(diethylamino)ethyl methacrylate as monomer, and ^ optionally 0% to 5% by mass, preferably 1% by mass, of a photo-tightener selected from 2,4,6-Trimethylbenzoyldi-Phenylphosphinate (TPO L, TCI, CAS 84434-11-7, 95% by mass), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO, Sigma Aldrich, CAS 75980-60-8, 97% by mass), or 1-Hydroxycyclohexyl phenyl ketone (HCHPK, Sigma Aldrich, CAS 947-19-3, 99% by mass). Of course, the sum of all the components in the composition equals 100%.The compositions described in Table 4 were prepared according to the protocol above. In these compositions, the PGS-IA is that of Example 2, the photoinitiator used is TPO L, and the monomer used is 2-(diethylamino)ethyl methacrylate. [TABLE 4] No. Composition (% mass) PGS- PGS- TPO Compound M FLO-MA FLO vinyl esterIA MA L 1100 0 0 0 0 02 0 100 0 0 0 03 54.5 0 1 44.5 0 05 45 0 1 35 19 06 45 0 1 35 0 197 0 45 1 35 19 08 0 45 1 35 0 199 0 54.4 1 44.5 0 0 Example 5: Photocrosslinking The composition of example 4 is positioned under a UV lamp (LED 365nm, 9 mw / cm2) for an exposure time of 1 to 240 minutes, at room temperature and atmospheric pressure, in the presence or without photoinitiator.The progress of crosslinking is defined by monitoring in the mid-infrared (MIR, ATR Mono-reflection equipped with a germanium crystal) via the disappearance of the C=C band of itaconate at 1638 cm⁻¹ as a function of UV irradiation time, by monitoring the evolution of the glass transition temperature, Tg by differential scanning calorimetry (DSC), by the evolution of the complex shear modulus, G* by MCR rheometer. Kinetics The kinetics of photocrosslinking is determined by infrared monitoring (notably MIR, Mid-Infrared) of the disappearance of the C=C band of itaconate (at 1638 cm⁻¹). -1) as a function of time. More precisely, a drop of the composition is placed on the germanium crystal (in an ATR Mono-reflection apparatus) and then irradiated under a UV lamp (365 nm, 9 mW / cm²) placed 5 cm from the crystal, and the reaction in the droplet deposited on the crystal is monitored. The times indicated (in seconds) in Table 5 correspond to the minimum time required for the complete disappearance of the C=C band of itaconate (at 1638 cm⁻¹). -1 ). [TABLE 5] No. Composition (% by mass) Kinetics PGS- PGS- TPO FLO vinyl Kinetics of C omposé M FLO-MAIA MA L ester crosslinking 1100 0 0 0 0 0 12 0002 0 100 0 0 0 0 6003 54.5 0 1 44.5 0 0 1855 45 0 1 35 19 0 756 45 0 1 35 0 19 1907 0 45 1 35 19 0 458 0 45 1 35 0 19 549 0 54.4 1 44.5 0 0 48 It is observed that the reaction kinetics are significantly increased in the presence of a co-crosslinking agent of formula (I), compared to a composition containing neither a co-crosslinking agent nor monomer M. The addition of a co-crosslinking agent also allows for equally good, or even better, results. than with a single monomer M. Storage modulus The storage modulus is also measured on the compositions obtained by crosslinking. The results obtained are summarized in Table 6. [TABLE 6] No. Composition (% mass) Storage modulus PGS- PGS- TPO FLO vinyl C omposé M FLO-MAat 37°C, 10 Hz (MPa) IA MA L ester 545 0 1 35 19 0 1.72 46 45 0 1 35 0 19 0.23 17 0 45 1 35 19 0 0.35 38 0 45 1 35 0 19 0.65 7 For compositions WITHOUT a co-crosslinking agent, the crosslinked copolyesters obtained are too liquid for a reliable measurement of the storage modulus to be carried out. The storage modulus of the compositions is therefore significantly increased with the addition of a co-crosslinking agent of formula (I).

Claims

CLAIMS 1. A photocrosslinkable composition comprising: a photocrosslinkable copolyester selected from (i) a copolyester whose constituent units are obtained by the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, or (ii) a copolyester whose constituent units are obtained by the polymerization of glycerol with a dicarboxylic acid monomer, said copolyester being further functionalized with an acrylic monomer, the acrylic monomer being selected from itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, mesaconic anhydride, (meth)acrylic acid, (meth)acrylic anhydride, (meth)acryloyl chloride, C1-C6 alkyl esters of (meth)acrylic acid, or a mixture thereof; a cocrosslinking agent of the following general formula (I): : in which X1 independently represents H or a group L1-R1, X2 independently represents H or a group L2-R2, X3 independently represents H or a group L3-R3, X4 independently represents H or a group L4-R4, X5 independently represents H or a group L5-R5, X6 independently represents H or a group L6-R6, each of L1, L2, L3, L4, L5 and L6 is independently absent or represents -C(O)- ;-S- ; -S(O)- ; -S(O)2- ; -NRa- ;or a linear or branched, saturated or unsaturated but non-aromatic, divalent aliphatic chain of 1 to 10 carbon atoms, wherein 1 or more, in particular 1 to 4 methylene units (preferably non-adjacent), are optionally replaced by -C(O)-, -O-, -OC(O)-, -C(O)-O-, -NRb-C(O)-, -C(O)Rc-, -S-, -S(O)-, -S(O)2-, -NRd-, said aliphatic chain being optionally substituted by one or more aryl or ORe substituents, with Ra, Rb, Rc, Rd and Re independently representing H or a C1-C6 alkyl group, R1, R2, R3, R4, R5 and R6 independently representing H or a vinyl group; formule with R representing H or a C1-C6 alkyl, preferably H or a methyl, at least two of the groups R1, R2, R3, R4, R5 and R6 representing a vinyl group, the vinyl group being bonded to the L1, L2, L3, L4, L5 or L6 group respectively, or directly to the oxygen atom when the L1, L3 and / or L5 groups are absent, or to the rest of the molecule when L2, L4 and / or L6 are absent.

2. Composition according to claim 1, characterized in that the photocrosslinkable copolyester has a C=C double bond ratio greater than or equal to 0.004 mmol / g, preferably greater than or equal to 0.04 mmol / g or 0.1 mmol / g, advantageously greater than or equal to 0.5 mmol / g, more preferably greater than or equal to 1 mmol / g. 3.Composition according to claim 1 or 2, characterized in that each of L1, L2, L3, L4, L5 and L6 is independently absent or represents a -C(O)- group or a linear or branched, saturated or unsaturated but non-aromatic, divalent aliphatic chain of 1 to 10 carbon atoms, wherein one or more, in particular one to four methylene units, are optionally replaced by -C(O)-, -O-, -OC(O)-, -C(O)-O-, said aliphatic chain being optionally substituted by one or more aryl or ORe substituents with Re selected from H or an alkyl group in C1-C6.

4. Composition according to any one of claims 1 to 3, characterized in that X2, X4 and X6 represent H.

5. Composition according to any one of claims 1 to 4, characterized in that the co-crosslinking agent is chosen from the group consisting of compounds of general formulas (Ia), (Ib), (Ic), and (Id):. in which R, R' and R'' independently represent H or a C1-C6 alkyl, preferably H or a methyl, and n1, n3, n5, m1, m3, m5 independently represent an integer from 1 to 6, preferably 1 or 2, the co-crosslinking agent being advantageously chosen from the group consisting of 6. A composition according to any one of claims 1 to 5, characterized in that the co-crosslinking agent is present at a content of 5% to 90%, in particular 10% to 80%, preferably 15% to 50%, by mass relative to the total mass of the composition.

7. A composition according to any one of claims 1 to 6, further comprising a photoinitiator, advantageously at a content of 0.05% to 5%, preferably 0.1% to 4%, in particular 0.2% to 3%, by mass relative to the total mass of the composition.

8. A composition according to any one of claims 1 to 7, further comprising a compound M, liquid at room temperature and comprising a radical polymerizable function, this radical polymerizable function radical being an acrylic function, typically of formula representing H or a C(O)ORf group, and with Rf representing H, or a C1-C alkyl 10, the alkyl group at C1-C 10 being unsubstituted or substituted by one or more, preferably one or two, alkoxy group(s) at C1-C6, alkenyl at C2-C6, NR p1 R p2 or NR p1 R p2 R p3 + X-, with R p1 , R p2 and R p3 independently representing H or a C1-C6 and X- alkyl group representing a negatively charged counterion such as a halide, hydrogen sulfate (HSO4-) or bisulfite (HSO3-), the acrylic group being linked to the rest of the molecule by the bond.

9. Composition according to claim 8, characterized in that compound M is a compound of formula (II), (III), (IV), or (V): in which: R represents H or a C1-C6 alkyl, preferably H or a methyl, Rf and Rf' independently represent H, a C1-C10 alkyl, the C1-C10 alkyl group being unsubstituted or substituted by one or more, preferably one or two, C1-C6 alkoxy, C2-C6 alkenyl, NRn1Rn2 or NRn1Rn2Rn3 groups +X-, with Rn1, Rn2 and Rn3 independently representing H or a C1-C6 alkyl group and X- representing a negatively charged counterion such as a halide, hydrogen sulfate (HSO4-) or bisulfite (HSO3-).

10. Composition according to claim 8 or 9, characterized in that compound M is present at a content from 1% to 90%, in particular from 10% to 80%, preferably from 30% to 70%, by mass relative to the total mass of the composition. 11.A composition according to any one of claims 1 to 10, characterized in that the photocrosslinkable copolyester has at least one of the following characteristics: - its number-average molar mass (Mn) is greater than or equal to 500 g / mol, in particular greater than or equal to 1000 g / mol, advantageously greater than or equal to 1500 g / mol, preferably greater than or equal to 2000 g / mol; - its number-average molar mass (Mn) is less than 10,000 g / mol, in particular less than or equal to 3500 g / mol, preferably less than or equal to 3000 g / mol; - its dispersity Δ (Mw / Mn) is less than 10, preferably less than or equal to 8, in particular less than or equal to 6, the number-average molar mass (Mn) and the dispersity Δ (Mw / Mn) being measured by size-exclusion chromatography with differential refractometer detection (SEC-RI).

12. A method for photocrosslinking the photocrosslinkable composition according to any one of claims 1 to 11, comprising a UV irradiation step of the photocrosslinkable composition.

13. A crosslinked composition obtained by crosslinking the photocrosslinkable composition according to any one of claims 1 to 11.

14. A crosslinked composition according to claim 13, characterized in that it has a storage modulus G' at 37°C and 10 Hz ranging from 0.05 to 10 MPa and preferably from 0.2 to 2 MPa, the storage modulus G' being measured in accordance with the method described in the examples.

15. Use of the photocrosslinkable composition of any one of claims 1 to 11 for the preparation of products by 3D printing.

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