COMPOSITIONS DE COPOLYESTERS PHOTORETICULABLES

Abstract

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

Description

Title of the invention: PHOTORETICULABLE COPOLYESTER COMPOSITIONS FIELD OF INVENTION

[0001] The present invention relates to photocurable 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

[0002] 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.

[0003] Conventionally, PGS by melt polycondensation of glycerol and a diacid, at high temperature and under reduced pressure, with fairly long reaction times.

[0004] However, with the development of 3D printing application techniques, which require working at near ambient temperature, under atmospheric pressure, and preferably with short reaction times, new materials have been sought whose preparation processes would be compatible with the requirements of 3D printing application, while maintaining satisfactory thermo-mechanical properties.

[0005] Similarly, conventional processes are also not compatible with the integration into the biomaterial of temperature-sensitive organic molecules.

[0006] Thus, photocrosslinkable materials have been developed obtained by copolymerization of glycerol with sebacic acid and unsaturated acids, the unsaturations being able to subsequently be subjected to a photocrosslinking reaction for example under UV irradiation (see in particular WO2019 / 215441 and WO2021 / 078962).

[0007] 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 bio-sourced, allowing the production of photocrosslinkable polymers usable for a wide range of applications, including biomedical ones, with a relatively low carbon footprint.

[0008] Thus, Rueben et al. (MRS Advances (2018), 3(27), 1551-1556) describe the synthesis of copolymers of glycerol, sebacic acid and itaconic acid, but with particularly long preparation times (24h).

[0009] Patent application CN11445635 also describes copolymers of polyols, aliphatic diacids, and itaconic acid, and in particular copolymers of glycerol, sebacic acid, and itaconic acid. However, the inventors have demonstrated that the polycondensation preparation process of CN11445635 is not reproducible. Indeed, under the described conditions, uncontrolled side reactions (in particular crosslinking reactions) are observed, linked to the reactivity of the α,[3-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, for example.

[0010] There is therefore a need for photocurable copolyester compositions whose preparation process is simple, reliable, and reproducible, and particularly suitable for industrial scale, avoiding the occurrence of uncontrolled side reactions. The use of specific crosslinking agents significantly reduces crosslinking times, making photocurable copolyester compositions usable in 3D printing processes, particularly at room temperature and atmospheric pressure. The monomers used will preferably be non-toxic and bio-based, in order to limit the carbon footprint of the resulting copolyesters. Furthermore, the processing temperatures are generally lower than in conventional processes and are advantageously compatible with high-temperature sensitive organic molecules. BRIEF SUMMARY OF THE INVENTION

[0011] Surprisingly, the inventors have demonstrated that adding a co-crosslinking agent of general formula (I) during the crosslinking of the photocrosslinkable copolyester does indeed improve the thermomechanical properties of the resulting crosslinked copolyester, compared to copolyesters obtained without a co-crosslinking agent. This also allows for increased photocrosslinking rates and the use of preferably non-toxic and bio-based compounds, thus making the process more environmentally friendly.

[0012] The present invention thus has as its first object a photocurable composition comprising:

[0013] - a photocurable copolyester selected from (i) a copolyester whose units constitutional units are derived from the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, or (ii) a copolyester whose constitutional units are derived from the polymerization of glycerol with a dicarboxylic acid monomer, said copolyester being subsequently functionalized with an acrylic monomer,

[0014] 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, Ci-C6 alkyl esters of (meth)acrylic acid, or a mixture thereof#;

[0015] - a co-crosslinking agent of the following general formula (I):

[0016] in which

[0017] Xi independently represents H or a group LrRi,

[0018] X2 independently represents H or a group L2-R2,

[0019] X3 independently represents H or a group L3-R3,

[0020] X4 independently represents H or a group L4-R4,

[0021] X5 independently represents H or a group L5-R5,

[0022] X6 independently represents H or a group L6-R6,

[0023] each of Lb 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 ORe substituents,

[0024] with Ra, Rb, Rc, Rd and Re independently representing H or an alkyl group in Cr C6,

[0025] Ri, R2, R3, Ri, R5 and R6 independently represent H or a vinyl group of formula with R representing H or a Ci-C6 alkyl, preferably H or a methyl, at least two of the RB groups R2, R3, R, R5 and R6 representing a vinyl group,

[0026] the vinyl group being linked by the -¼ bond to the Lh group L2, L3, L4, L5 or L6 respectively, or directly to the oxygen atom when the Lb groups L3 and / or L5 are absent, or to the rest of the molecule when L2, L4 and / or L6 are absent.

[0027] The present invention also has as its second object a method for photocrosslinking a photocrosslinkable composition according to the invention, comprising a step of UV irradiation of the photocrosslinkable composition.

[0028] The present invention has as its third object a crosslinked composition obtained by crosslinking a photocrosslinkable composition according to the invention.

[0029] The present invention has as its fourth object the use of a composition photocurable according to the invention for the preparation of products by 3D printing. DETAILED DESCRIPTION OF THE INVENTION

[0030] For the purposes of the present invention, the term “a” or “an” means “one or more” or “at least one”.

[0031] For the purposes of the present invention, a range of values ​​designated by the expression "between a and b" represents the range of values ​​from greater than strictly a, to less than strictly b (that is to say excluding the bounds a and b), while any range of values ​​designated by the expression "from a to b" represents the range of values ​​from a to b, that is to say including the strict bounds a and b.

[0032] In this description, "approximately" means that the value in question may be 10% lower or higher, in particular 5%, and especially 1% higher, than the value indicated.

[0033] 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 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 includes, in particular, monomers, specifically glycerol, dicarboxylic acid, and acrylic monomer.

[0034] Glycerol is a triol with the following formula: QH HO.. OH

[0035] For the purposes of this invention, a "photocrosslinkable" polymer (including a copolyester) is defined as a polymer which, 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.

[0036] 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, in particular around 25°C.

[0037] By "atmospheric pressure" we mean here a pressure of about 1 bar.

[0038] By "aliphatic" we mean a linear, branched and / or cyclic hydrocarbon group, whether saturated or unsaturated but non-aromatic.

[0039] A "divalent aliphatic chain" means a linear or 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. For the purposes of this invention, an "alkanediyl" group means 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. For the purposes of this invention, an "alkeniyl" group is defined as a linear or branched acyclic divalent hydrocarbon chain comprising 2 to 10 carbon atoms and at least one double bond, such as, for example, a vinylene (ethenylene) or propenylene group.For the purposes of this invention, an "alkynediyl" group is defined as a divalent, linear or branched, acyclic hydrocarbon chain comprising 2 to 10 carbon atoms and at least one triple bond.

[0040] The term "C1-C2 alkyl group" here refers to a monovalent, saturated, linear or branched hydrocarbon chain comprising from 1 to 6 carbon atoms, preferably comprising from 1 to 4 carbon atoms. Examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexyl groups.

[0041] For the purposes of this invention, the term "alkenyl (C2-C6) group" means a monovalent, linear or branched hydrocarbon chain comprising at least one double bond and consisting of 2 to 6 carbon atoms. Examples include ethenyl, propenyl, allyl, butenyl, pentenyl, and hexenyl groups.

[0042] The term "(C3-C7)cycloalkyl" or "(C3-C7) cycloalkyl" refers, in the context of the present invention, to a saturated cyclic hydrocarbon chain comprising 3 to 7 cyclic carbon atoms. A cycloalkyl may be monocyclic or bicyclic. Examples include cyclopropyl, cyclopentyl, cyclohexyl, and cycloheptyl groups.

[0043] 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. An example of a monovalent aromatic group is a phenyl or naphthyl group, advantageously phenyl.

[0044] As used herein, 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 (13C NMR).

[0045] The C=C double bond ratio can also be obtained indirectly by quantifying the free acrylic derivative or monomer by 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 amount) and the amount of free acrylic derivative or monomer, these amounts being expressed in mmol / g of polymer obtained.

[0046] For the purposes of this invention, "halogen atom" or "halogen" means fluorine, chlorine, bromine and iodine atoms.

[0047] By "halide" we mean here the fluoride (F), bromide (Br), chloride (Cl) and iodide (I) ions.

[0048] For the purposes of this invention, the term "alkyl group (C1-C1E)" refers to a monovalent, saturated, linear or branched hydrocarbon chain comprising 1 to 6, preferably 1 to 4, carbon atoms. Examples include methyl, ethyl, propyl, isopropyl, butyl, pentyl, and hexyl groups.

[0049] For the purposes of this invention, the term "(Ci-C6)alkyl alkoxy group" refers to a (Ci-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.

[0050] 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, for example, a phenyl or naphthyl group. Advantageously, it is phenyl.

[0051] By "heteroaryl," we mean here an aromatic group comprising 5 to 10 cyclic atoms, one or more of which are heteroatoms, advantageously 1 to 4 and even more advantageously 1 or 2, such as, for example, sulfur, nitrogen, or oxygen atoms, the other cyclic atoms being carbon atoms. Examples of heteroaryl groups are furyl, thienyl, pyrrolyl, pyridinyl, imidazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, and pyrazolyl groups. oxadiazolyl, thiadiazolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, quinolyl, isoquinolyl, quinoxalyl or indyl.

[0052] A “photoinitiator” is understood to be a compound which, when exposed to light, and in particular to UV light, produces a radical which will initiate the photocrosslinking reaction, which is generally radical.

[0053] 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 crosslinking of the polymer, or Michael reactions.

[0054] A phenol is understood to be an organic compound comprising a phenol function: ,.OH, substituted or unsubstituted, in particular by a or several substituents chosen from a halogen atom, -NO2, or an alkyl group in Ci-C6, alkoxy in Ci-C6, NH-alkyl in Ci-C6.

[0055] An aniline is understood to be an organic compound comprising an aniline function: with Rn representing H or a C1-C6 alkyl group, substituted or ■■rir j unsubstituted, in particular by one or more substituents chosen from a halogen atom, -NO2, or a Ci-C6 alkyl group, Ci-C6 alkoxy, Ci-C6 NH-alkyl. 1. Photocrosslinkable composition

[0056] The photocurable composition comprises:

[0057] - a photocurable copolyester selected from (i) a copolyester whose units constitutional units are derived from the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, or (ii) a copolyester whose constitutional units are derived from the polymerization of glycerol with a dicarboxylic acid monomer, said copolyester being subsequently functionalized with an acrylic monomer,

[0058] 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, Ci-C6 alkyl esters of (meth)acrylic acid, or a mixture thereof#;

[0059] - a co-crosslinking agent of the following general formula (I):

[0060] in which

[0061] Xi independently represents H or a group LrRi,

[0062] X2 independently represents H or a group L2-R2,

[0063] X3 independently represents H or a group L3-R3,

[0064] X4 independently represents H or a group L4-R4,

[0065] X5 independently represents H or a group L5-R5,

[0066] X6 independently represents H or a group L6-R6,

[0067] each of Lb 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 ORe substituents,

[0068] with Ra, Rb, Rc, Rd and Re independently representing H or an alkyl group in Cr C6,

[0069] Ri, R2, R3, Rj, R5 and R6 independently represent H or a vinyl group of formula with R representing H or a Ci-C6 alkyl, preferably H or a methyl, at least two of the Rb groups R2, R3, R, R5 and R6 representing a vinyl group,

[0070] the vinyl group being linked by the 'y- bond to the Lh group L2, L3, L4, L5 or L6 respectively, or directly to the oxygen atom when the Lb groups L3 and / or L5 are absent, or to the rest of the molecule when L2, L4 and / or L6 are absent. Photocurable copolyester

[0071] The dicarboxylic acid monomer may be aliphatic, aromatic, or aliphatic / aromatic. The dicarboxylic acid monomer may not 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.

[0072] 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 x to y carbon atoms.

[0073] 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).

[0074] The acrylic monomer is preferably chosen from (meth)acrylic acid, (meth)acrylic anhydride, itaconic acid and itaconic anhydride, or a mixture of these, more preferably (meth)acrylic anhydride, itaconic acid and itaconic anhydride, or a mixture of these.

[0075] 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, even more preferably greater than or equal to 1 mmol / g.

[0076] The photocurable copolyester may also have 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 3,500 g / mol, preferably less than or equal to 3,000 g / mol; • its dispersity D (Mw / Mn) is less than 10, preferably less than or equal to 8, in particular less than or equal to 6.

[0077] The number-average molar mass (Mn), the mass-average molar mass (Mw), and the dispersity (also called polydispersity, D dispersity, which is the Mw / Mn ratio) can be measured in a known manner by SEC analysis, in particular as described below. The residual monomer content and the (1,2,3-triacylglyceride) unit content are measured in a known manner by ¹H NMR, where appropriate combined with 2D HSQC / HMBC and ¹³C NMR experiments, as described below.

[0078] 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.

[0079] 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 glycerol copolyester and an unfunctionalized dicarboxylic acid monomer with an acrylic monomer selected from itaconic acid, itaconic anhydride, (meth)acrylic acid, Ci-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 sufficient time to form a photocurable functionalized copolyester, c. Cooling and recovery of the photocurable functionalized copolyester.

[0080] The copolyester of glycerol and a dicarboxylic acid monomer (non-functionalized) can be obtained in particular by implementing the processes described in EP3149067 and EP1448656.

[0081] The copolyester of glycerol and an unfunctionalized dicarboxylic acid monomer advantageously has one or more of the following characteristics: - an average number molar mass (Mn) of the non-functionalized 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 non-functionalized copolyester less than or equal to 10,000 g / mol, preferably less than or equal to 3,500 g / mol, preferably less than or equal to 3,000 g / mol; - a dispersity D (Mw / Mn) of the non-functionalized copolyester of less than 10, preferably less than or equal to 8; - a residual monomer content of less than or equal to 5% by weight of the weight of the non-functionalized copolyester; - a rate of (1,2,3-triacylglyceride) units less than or equal to 20 mol% relative to all units of the non-functionalized copolyester; - a molar ratio of the (1,3-diacylglyceride) unit to the (1,2-diacylglyceride) unit greater than 1 of the unfunctionalized copolyester.

[0082] The residual monomer content and the (1,2,3-triacylglyceride) unit content are measured in a known manner by 13C NMR, where appropriate combined with 2D HSQC / HMBC and 13C NMR experiments, as described below.

[0083] 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 13C NMR, 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 described in ASTM E222-23. This method involves acetylating the hydroxyl groups present with acetic anhydride and then titrating the KOH. The hydroxyl number is then easily converted by a person skilled in the art into mmol of free OH / g of copolyester.

[0084] Advantageously, the molar ratio of acrylic monomer / NOH varies from 1:100 to 2:1, in particular from 1:1 to 2:1.

[0085] The step (a) of bringing the non-functionalized copolyester into contact with an acrylic monomer is typically carried out at a temperature between 20°C and 200°C.

[0086] According to embodiments, the contacting in step a) is carried out in the absence of solvent or diluent.

[0087] Alternatively, in step (a), the unfunctionalized copolyester and the acrylic monomer can be contacted in a solvent, in particular water. Typically, water is added in a mass quantity ranging from 0% to 100% by mass, preferably from 5% to 50% by mass, and more preferably from 10% to 40% by mass relative to the mass of unfunctionalized copolyester and acrylic monomer involved. To promote homogenization of the medium, agitation can be carried out in a known manner.

[0088] The stabilizing agent can also be added during step a).

[0089] In step (b), the functionalization reaction comprises an esterification of a free alcohol function of the glycerol copolyester and a dicarboxylic acid monomer by the acrylic monomer. Depending on the reaction conditions, transesterification reactions may also occur, but these generally remain minor.

[0090] According to one embodiment, 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 water thus recovered is recycled as a solvent for the contacting step (a).

[0091] The pressure in the reactor during step (b) can be constant or variable. The functionalization step (b) is preferably conducted at a pressure between 0.0001 and 2 bar.

[0092] 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.

[0093] Any method known to a person skilled in the art can be used to lower the pressure, in particular using a pump (in particular a vane pump), a diaphragm pump, rotary pump, etc. Such an intermediate pressure is less than 1 bar and varies for example from 800 mbar to 50 mbar.

[0094] Step b) of heating is preferably carried out at a temperature between 20°C and 250°C. The temperature of step b) of heating may be variable or constant.

[0095] The temperature is preferably reached by applying an isotherm or a heating ramp. The heating ramp may include one or more stages, also called temperature holding periods, and the ramp typically has a slope of between +0.1°C / min and +1°C / min.

[0096] According to one embodiment, 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 is composed of a food-grade catalyst, that is, a catalyst suitable for food contact (for animals and humans) that meets requirements ensuring that there is no risk of toxicity induced by this catalyst for the polyester produced. Such a catalyst meets, in particular, the requirements of U.S. standards 21 CFR 175.300, 21 CFR 177.2420, and / or 21 CFR 175.105 in force at the filing date.

[0097] The food grade catalyst is advantageously tin-based, in particular monobutyltin oxide marketed under the name FASCAT 9100 by PMC Organometallix.

[0098] Advantageously, the heating in step b) is carried out for 30 minutes at 12:00, preferably for 1 hour at 5:00.

[0099] Step c) of cooling is carried out in a manner known to a person skilled in the art.

[0100] 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.

[0101] The acrylic monomer can be added at the same time as the glycerol and the dicarboxylic acid monomer, or in a later step.

[0102] Typically, the process comprises:

[0103] a') a step of contacting the glycerol with the dicarboxylic acid monomer and at least one acrylic monomer, and a stabilizing agent, and

[0104] b') a polycondensation step under reduced pressure, the pressure being 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, and preferably at a temperature between 110°C and 200°C, preferably between 120°C and 180°C, especially at 130°C.

[0105] According to another embodiment, the process comprises:

[0106] a”) a step of contacting glycerol with diacid monomer carboxylic, 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.

[0107] The polycondensation step d”) is preferably carried out at a temperature between 50°C and 250°C, preferably between 100°C and 200°C, and in particular between 120°C and 190°C. The target temperature of the polycondensation step d”) may 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 the ramp typically has a slope of between +0.1°C / min and +1°C / min.

[0108] Working under reduced pressure during the polycondensation steps makes it possible to improve the efficiency and kinetics of the corresponding polycondensation step.

[0109] The steps (a') and (a”) of contacting the glycerol with the dicarboxylic acid monomer and optionally at least one acrylic monomer, are typically carried out at a temperature between 20°C and 100°C.

[0110] During step (a') or (a”), the glycerol and dicarboxylic acid monomers may be brought into contact with water. The addition of water to the monomer mixture allows for homogenization of the mixture and thus reduces its overall viscosity. To promote this homogenization, stirring may be carried out in a known manner.

[0111] According to these variants, water is added to the monomers in a quantity by mass of between 0% and 100% by mass relative to the mass of the monomers involved, preferably from 5% to 50% by mass relative to the mass of the monomers involved, preferably still from 10% to 25% by mass relative to the mass of the monomers involved.

[0112] According to other particularly preferred embodiments, 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.

[0113] According to one embodiment, 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 may vary from ambient temperature to 130°C.

[0114] 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 that is relatively unreactive with respect to the crosslinking agent, such as a phenol or aniline.

[0115] Advantageously, the stabilizing agent is a compound with the general formula: ..... fo-l 'J ' 'p '-''ZH

[0116] in which

[0117] Z represents O or NRq with Rq representing H or alkyl in Ci-C6,

[0118] Rxi represents H, -CO-aryl or -CO-heteroaryl,

[0119] Rx2 independently represents H, halogen, -NO2, -OH, Ci-C6 alkoxy, -COOH, Ci-C6 -COO-alkyl, CrC6 NH-alkyl, -SRs, or Ci-C6 alkyl optionally substituted by ORS or SRs,

[0120] Rs independently represents a Ci-C8 alkyl and

[0121] p is an integer from 1 to 4, preferably 1 or 2.

[0122] Preferably, p is 1 or 2, and Rx2 independently represents H, -OH, -COOH, alkyl in Ci-C6 optionally substituted by an alkoxy in Ci-C6 or SRs in which Rs is as defined above.

[0123] Advantageously, Rxi represents H or -CO-phenyl.

[0124] The stabilizing agent can be used alone or in a mixture.

[0125] Typically, this includes aniline, phenol, methoxyphenol (in particular 4-methoxyphenol or guaiacol), syringol, 4,6-bis(octylthiomethyl)-o-cresol and / or 2-hydroxy-4-methoxybenzophenone.

[0126] The quantity of stabilizing agent introduced is advantageously between 0.01% and 5% by mass relative to the total mass of the monomers and possibly of the acrylic monomer, preferably between 0.1% and 2%, preferably between 0.5% and 1.6%.

[0127] Preferably, the molar ratio of acrylic monomer / dicarboxylic acid monomer varies from 1 / 99 to 99 / 1, preferably from 10 / 90 to 90 / 10, advantageously from 20 / 80 to 80 / 20. Co-crosslinking agent

[0128] Preferably, each of Lb 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 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 ORe substituents with Re selected from H or a Ci-C6 alkyl group.

[0129] Advantageously, R2, R4, and R6 represent H and Ri, R3, and R5 independently represent H or a vinyl group of formula $ as defined above, provided that at least two groups among RB, R3, and R5 are a vinyl group. Preferably, R2, R4, and R6 represent H and Ri, R3, and R5 independently represent a vinyl group of formula as defined above.

[0130] Advantageously, X2, X4 and X6 represent H.

[0131] Preferably, the co-crosslinking agent is chosen from the group consisting of compounds with general formulas (la), (Ib), (le), and (Id): (the), and O Fr,, A '0' (Id), R: (CH- QH tCHgA 'O' '0 H' OH

[0132]

[0133]

[0134]

[0135] in which R, R' and R” independently represent H or an alkyl group in C1-C6, preferably H or a methyl group, and ni, n3, n5, ml, 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 the compounds: A, AA', O' O' .OH '0' , and their mixtures. o A OH QH

[0136]

[0137]

[0138] Advantageously, the co-crosslinking agent is present at a content 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 content 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. Photocuring agents suitable for photoreticulation are well known to those skilled in the art. They can be, in particular, of type I or type II. Type I photoinitiators are monomolecular 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 position α with respect to the carbonyl group (Norrish I 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 / 10th 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).

[0139] Type I photoinitiators are in particular any benzoyl radical precursor: Kind ! zssx UV R -¾. ------------------------------R “4 •Alkyl-R ' ■' 6 ô Radical tenzoyie Radical hsczyte, a^yie

[0140] Type II photoinitiators are in particular any precursor of a cetyl radical (inert) and with a radical precursor (an amine). Type II R—¢( —'îr'"4 4"”^ ■* “-------------------------$—4 T—*—4 * CHjNHRj Q Radical cetvle (inerte; .

[0141] The photoinitiators will in particular be chosen from the family of type I photoinitiators. In particular, we can mention 2,4,6-Trimethylbenzoyldi-Phenylphosphinate (TPO L), diphenyl(2,4,6-trimethylbenzoyl) phosphine oxide (TPO), or 1-Hydroxycyclohexyl phenyl ketone (HCHPK).

[0142] Advantageously, the composition further comprises a compound M, liquid at room temperature and comprising a radical polymerizable function, this radical polymerizable function preferably being an acrylic function, typically of formula O or with Yi representing H or a C(O)ORf group, and with Rf representing H, or a Ci-C1 alkyl, the alkyl group being unsubstituted or substituted by one or more, preferably one or two, Ci-C6 alkoxy, C2-C6 alkenyl, NRpiRp2 or NRpiRp2Rp3+X, with 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),

[0143] the acrylic group being linked to the rest of the molecule by the

[0144] bond. Advantageously, compound M further comprises one or more advantageously selected functions from: • An amine function, in particular a -NRniRn2 or -NRniRn2Rn3+ group , with Rni, Rn2 and Rn3 independently representing H or a Ci-C6 alkyl group and X representing a counterion carrying a negative charge such as a halide, hydrogen sulfate (HSO4) or bisulfite (HSO3 ), • A carboxylic acid function or a carboxylic ester function.

[0145] 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.

[0146] Advantageously, the monomer M is an unsaturated alpha-beta ester optionally substituted by a second ester function, such as itaconic acid, itaconic anhydride, (meth)acrylic acid, or a derivative thereof, or mixtures thereof.

[0147] Advantageously, compound M is a compound of formula (II), (III), (IV) or (V): O (II), R. .A. - , )■ O Rf (III), (IV), or

[0148] in which

[0149] R represents H or an alkyl group in CrC6, preferably H or a methyl group,

[0150] Rf and Rf independently represent H, a C1-C1 alkyl group, the C1-C1 alkyl group being unsubstituted or substituted by one or more, preferably one or two, C1-C6 alkoxy, C2-C6 alkenyl, NRniRn2 or NRniRn2Rn3+X groups, with Rn[, Rn2 and Rn3 independently representing H or a Ci-C6 alkyl group and X representing a counterion carrying a negative charge such as a halide, hydrogen sulfate (HSO4) or bisulfite (HSO3).

[0151] Preferably, compound M is a Ci-C6 alkyl diester of itaconic acid, or a Ci-Cio alkyl ester of methacrylic acid. Examples of compound M are dimethylitaconate, butyl methacrylate, and 2-ethylhexyl methacrylate.

[0152] Typically, compound M is present at a content 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.

[0153] According to embodiments, the composition does not include additives, in particular conventional additives.

[0154] According to embodiments, the photocurable composition may further comprise one or more conventional additives in the art, such as fillers.

[0155] The composition may further include an additive chosen from the group consisting of colorants, 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.

[0156] The colorants and organic fillers are well known to those skilled in the art. The stabilizing agents are typically as defined above.

[0157] According to some embodiments, the photocrosslinkable composition may include a molecule of interest.

[0158] 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

[0159] The invention also relates to a method of photocrosslinking the photocrosslinkable composition described herein, comprising a step of UV irradiation of the photocrosslinkable composition or of the photocrosslinkable copolyester, preferably in the presence of a photoinitiator.

[0160] Advantageously, the irradiation is conducted at a temperature ranging from 0°C to 200°C, in particular from 5 to 150°C, preferably from 10 to 100°C.

[0161] Irradiation is typically conducted at atmospheric pressure. It can be carried out under air or under an inert atmosphere, in particular under N2 scanning.

[0162] Preferably, the irradiation is carried out at a wavelength ranging from 250 nm to 500 nm, preferably from 300 to 450 nm, and even more preferably from 350 to 400 nm, in particular 365 nm. A person skilled in the art will be able to adapt the irradiation power, in particular according to the wavelength and the distance of the wave source to the composition to be irradiated.

[0163] The duration of irradiation typically varies from 0.1 s to 240 minutes, in particular from 1 s to 180 minutes.

[0164] Advantageously, the photoinitiator is present at a content less than or equal to 5% by mass, more preferably less than or equal to 1% by mass relative to the total mass of the photocurable composition.

[0165] The photoinitiators are as defined above.

[0166] 3. Uses of the photocurable composition

[0167] The photocurable composition according to the invention is useful for the preparation of products by 3D printing. The products are, for example, patches diffusing active ingredients, implants, particles (in particular micro- and macroparticles), coatings, fibers and threads, etc.

[0168] Indeed, during 3D printing, the photocurable composition undergoes crosslinking. In particular, 3D printing includes a focused irradiation step in a bath containing the photocurable composition, to form the products by photocrosslinking layer by layer. Alternatively, during 3D printing, the photocurable composition can be crosslinked by thermal crosslinking.

[0169] The invention therefore also relates to the use of the photocurable composition for the preparation of products by 3D printing, preferably by 3D printing by photocuring. Examples of such technologies are stereolithography (SLA), so-called "Digital Light Processing" (DLP) printing processes, "Continuous Liquid Interface Production" (CLIP), "Daylight Polymer Printing" (DPP), or "Film Transfer Imaging" (FTI). 4. Photoreticulated composition

[0170] The invention also relates to a crosslinked composition obtained by crosslinking, in particular thermal crosslinking and / or photocrosslinking, of the photocrosslinkable composition according to the invention.

[0171] According to one variant, the crosslinked composition can be obtained by the photocrosslinking process described above.

[0172] According to another variant, the crosslinked composition is likely to be obtained by thermal crosslinking, in particular with thermal initiation optionally in the presence of initiators chosen in particular from producers of radicals by thermal decomposition, such as peroxides, such as cumene hydroperoxide, or azo, such as razobiisobutyronitrile (AIBN), in dispersed or non-dispersed medium.

[0173] The photocrosslinked composition advantageously has a storage modulus G' at 37°C and 10 Hz varying from 0.05 to 10 MPa and preferably from 0.2 to 2 MPa. METHODS Structural analysis: NMR

[0174] 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 performed by NMR analysis. Spectra are acquired on a BRUKER Avance III 600 MHz spectrometer equipped with a 5 mm BBFO-zgrad broadband probe. The quantitative 1H NMR experiment uses a single 30° pulse sequence and a 3-second repetition delay between each of the 64 acquisitions. Samples are solubilized in a deuterated solvent, deuterated acetone (d6 acetone), unless otherwise specified. The 1H NMR spectrum, coupled with the 2D HSQC / HMBC and 13C NMR experiments, allows for the quantification of the microstructure of the different polyesters (see allocation tables). Macrostructure analysis: SEC RI

[0175] The SEC (Size Exclusion Chromatography) technique allows the separation of 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.

[0176] While not an absolute method, SEC allows for the determination of the molar mass distribution of a polymer. From commercial standard products, the various number-average (Mn) and weight-average (Mw) molar masses can be determined, and the polydispersity index (D = Mw / Mn), also called "dispersity," can be calculated.

[0177] The macrostructure of the copolyesters is analyzed by size-exclusion chromatography with differential refractometer detection (SEC RI), using low-weight polystyrene (PS) calibration 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 injection. The analysis temperature is 35°C, with a mobile phase flow rate of 1 L / minute on Agilent 2 Mixed E + 2 Mixed 2 columns. Structural analysis: MIR

[0178] Kinetic monitoring of photocrosslinking was performed with a mid-infrared (MIR) spectrometer with wavelengths between 4000 and 650 cm⁻¹*, (Vertex 70 model, marketed by Bruker) equipped with a germanium crystal on a Vertex 70-3 spectrometer with an MCT detector. A scan count (Ns) of 32 was used. The spectrometer was equipped with a 365 nm UV LED lamp with a power of 9 mW / cm², irradiating at a distance of 5 cm from the sample. Crosslinking was monitored by tracking the disappearance of the C=C band of itaconate at 1638cm1 as a function of UV irradiation time (measurement of the area of ​​the peak of the band at 1638cm').

[0179] Measurement of mechanical properties: storage modulus G'

[0180] The mechanical properties are measured on an Anton Paar model MCR302 rheometer, equipped with a 20mm diameter planar-planar geometry. The measurements are carried out on a cylindrical sample 2mm thick and 2cm in diameter, obtained by molding in a metal mold and then curing for 1 hour under a UV LED lamp (LED 365nm, 9Mw / cm2) at room temperature.

[0181] 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).

[0182] The modules G*, G' and G” are calculated according to the equations below:

[0183] G* = t

[0184] G*=G+iG"

[0185] with: • o the measured stress and e the deformation imposed on the sample. • G', the real part of G*, called the conservation modulus, which characterizes the stiffness of the viscoelastic material. G' characterizes the elastic behavior (the energy conserved and totally released by the material); • i, the "imaginary" unit (i2 = -1); • G", the imaginary part of G*, called the loss modulus or loss modulus dissipation, which characterizes viscous behavior (energy dissipated as heat). EXAMPLES

[0186] The following examples are given for illustrative purposes only, but should in no way be considered as limiting the present invention. I. Synthesis of photocrosslinkable copolyesters#

[0187] Example 1: Synthesis of unfunctionalized glycerol-co-sebacate copolyester, denoted PGS

[0188] 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, the water is removed by continuous. When the conversion exceeds 80% by measuring the quantity of water produced, the reaction is stopped.

[0189] The PGS thus obtained is recovered in the form of a white paste after cooling to room temperature. It has a number molar mass of approximately 1852 g / mol, a mass molar mass Mw of approximately 5067 g / mol, a dispersity of approximately D = 2.7, and a free hydroxyl content of 5 mmol / g.

[0190] Example 2: Synthesis of photocrosslinkable copolyesters according to the invention: itaconate-grafted glycerol-co-sebacetate copolyester

[0191] In the following, PGS-IA will be noted as a copolyester: glycerol-co-sebacate grafted itaconate obtained with itaconic acid as the acrylic monomer.

[0192] In a 500 mL double-jacketed reactor fitted with a distillation column, a condenser, and a distillate recovery trap, under a nitrogen flow, the PGS of Example 1, the acrylic monomer (0.4 molar equivalent 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 gradually heated to 130 °C (or 80 °C or 140 °C) under stirring 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 removed continuously during 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.

[0193] Test procedures 2.1 to 2.4 are carried out without solvents.

[0194] The reaction conditions of the different examples are summarized in Table 1.

[0195] The methacrylic anhydride functionalized PGS polyester, 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.

[0196] [Tables 1] Test 2.1 Test 2.2 Itaconic 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 obtained after cooling: yellow-orange viscous liquid; white viscous liquid

[0197] Table 2: Results of NMR (acetone d6) analyses of PGS-IA or PGS-MA obtained in tests 2.1 to 2.2

[0198] [Tables2] Test 2.1 Test 2.2 Structural characterization of the photocrosslinkable copolyester Molar % of 1-acylglyceride / polymer 2.8 Molar % of 2-acylglyceride / polymer 0.5 Molar % of 1,2-diacylglyceride / polymer 3.7 Molar % of 1,3-diacylglyceride / polymer 6.8 Molar % of 1,2,3-triacylglyceride / polymer 5.5 Molar % of grafted itaconic or methacrylic monomer / polymer 10.3 Molar % of free monomers or reagents Molar % of free glycerol 0.4 Molar % of free itaconic or methacrylic monomer 19.9 Molar % of OH in the product (mm³ / g) 3.3 Molar % of free itaconic or methacrylic monomer 16 Molar % of OH in the product (mm³ / g) 3.3 Molar % of free itaconic or methacrylic monomer 19.9 Molar % of free OH in the product (mm³ / g) 3.3 Molar % of free hydroxyl groups in the product (mm³ / g) Not determined. Quantity of unsaturates in the product or double bond ratio C=C* (mmol / g) «2.1 Not determined

[0199] *Takes into account the unsaturations of free and grafted itaconic acid or anhydride

[0200] Table 3: Calculation of average molar numbers (Mn) and mass (Mw) 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.

[0201] [Tables3] Mn (g / mol) Mw (g / mol) Dispersity, D Test 2.1 2271 29113 12.8 Test 2.2 1955 7515 3.8

[0202]

[0203] II - Synthesis of co-crosslinking agents of formula (I) Example 3.1: Preparation of 1,3,5-triyl tris(pent-4-enoate)benzene, denoted Flo- Vinyl ester, formula % Synthesis

[0204] 5 g (0.04 moles; the equivalent) of phloroglucinol are introduced into a tricol. The phloroglucinol is then degassed under an inert atmosphere. Next, 96 mL of dichloromethane, previously degassed with nitrogen (N2), is 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 added to the mixture. Then, 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 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).

[0205] The organic phase is evaporated under reduced pressure. 19.47g of crude product in the form of brown oil are obtained (NMR purity, CDC13: 54% mass). Purification

[0206] 19g of crude product are dissolved in 58mL of a petroleum ether / acetate mixture ethyl (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, CDC13: 65 wt.). 1 wt. of 4-methoxyphenol can be added to the product before the evaporation step to stabilize it. Example 3.2: Preparation of FLO-MA

[0207]

[0208]

[0209]

[0210]

[0211]

[0212]

[0213] The compound named FLO-MA with the formula "A" is synthesized GO gg following 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 in example 2 is mixed with other compounds as follows (mass percentages are expressed relative to the total mass of the composition): • from 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 from 0% to 5% by mass, preferably 1% by mass, of a photo-trigger 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 of 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. [Tables 4] Composition No. (% by mass) PGS-I A PGS-MA TPO L Compound M FLO-MA FLO vinyl ester 1 100 0 0 0 0 0 2 0 100 0 0 0 0 3 54.5 0 1 44.5 0 0 5 45 0 1 35 19 0 6 45 0 1 35 0 19 7 0 45 1 35 19 0 8 0 45 1 35 0 19 9 0 54.4 1 44.5 0 0 Example 5: Photoreticulation

[0214] 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 absence of a photoinitiator.

[0215] The progress of crosslinking is defined by monitoring in mid-infrared (MIR, ATR Mono-reflection equipped with a germanium crystal) via the disappearance of the C=C band of itaconate at 1638cm-l 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. Kinetic

[0216] The kinetics of the photocrosslinking are determined by infrared (particularly MIR, Mid-Infrared) monitoring of the disappearance of the C=C band of itaconate (at 1638 cm⁻¹) as a function of time. More precisely, a drop of the composition is deposited on the germanium crystal (in a Mono-reflection ATR apparatus) and then irradiated under a UV lamp (365 nm, 9 mW / cm²) placed 5 cm from the crystal, and the reaction in the drop deposited on the crystal is monitored.

[0217] The durations indicated (in seconds) in Table 5 correspond to the minimum time required for the complete disappearance of the C=C band of itaconate (at 1638cm1).

[0218] [Tables5] Composition No. (% mass) Kinetics PGS-I A PGS-MA TPO L Compound M FLO-MA FLO vinyl ester Crosslinking kinetics 1 100 0 0 0 0 0 12 000 2 0 100 0 0 0 0 600 3 54.5 0 1 44.5 0 0 185 5 45 0 1 35 19 0 75 6 45 0 1 35 0 19 190 7 0 45 1 35 19 0 45 8 0 45 1 35 0 19 54 9 0 54.4 1 44.5 0 0 48

[0219] 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.

[0220] The addition of a co-crosslinking agent also makes it possible to obtain results that are as good as, or even better than, those obtained with a monomer M alone. Storage module

[0221] The storage modulus is also measured on the compositions obtained by crosslinking.

[0222] The results obtained are summarized in Table 6.

[0223] [Tableauxô] Composition No. (% by mass) Storage modulus at 37°C, 100Hz (MPa) PGS-I A PGS-MA TPO L Compound M FLO-MA FLO vinyl ester 5 45 0 1 35 19 0 1.724 6 45 0 1 35 0 19 0.231 7 0 45 1 35 19 0 0.353 8 0 45 1 35 0 19 0.657

[0224] For compositions WITHOUT co-crosslinking agent, the crosslinked copolyesters obtained are too liquid for a reliable measurement of the storage modulus to be carried out.

[0225] The composition storage module is therefore significantly increased with the addition of a co-crosslinking agent of formula (I).

Claims

Demands

1. Photocurable composition comprising: • a photocrosslinkable copolyester selected from (i) a copolyester whose constituent units are obtained from the polymerization of glycerol with a dicarboxylic acid monomer and with an acrylic monomer, or (ii) 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, 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, Ci-C6 alkyl esters of (meth)acrylic acid, or a mixture thereof#; a co-crosslinking agent of the following general formula (I): in which Xi independently represents H or a group LrRi, 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 Lb 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 ORe substituents, with Ra, Rb, Rc, Rd and Re independently representing H or a CrC6 alkyl group, Ri, R2, R3, R4, R3 and R6 independently representing H or a vinyl group of formula 9 with R representing H or a CrC6 alkyl, preferably H or a methyl, at least two of the Rh groups R2, R3, R4, R5 and R6 representing a vinyl group, the vinyl group being linked by bonding to the Lb group L2, L3, L4, L5 or L6 respectively, or directly to the oxygen atom when the Lb groups L3 and / or L5 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 Lb 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 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 one or more aryl or ORe substituents with Re selected from H or a Ci-C6 alkyl group.

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 selected from the group consisting of compounds with general formulas (la), (Ib), (le), and (Id):

6. in which R, R' and R'' independently represent H or an alkyl group in Ci-C6, preferably H or a methyl group, and ni, n3, n5, ml, m3, m5 independently representing a number an integer from 1 to 6, preferably 1 or 2, the co-crosslinking agent being advantageously chosen from the group consisting of the compounds: , their mixtures. Composition according to any one of claims 1 to 5, characterized in that the co-crosslinking agent is present at a content 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.

7. Composition according to any one of claims 1 to 6, further comprising a photoinitiator, advantageously in 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 being an acrylic function, typically of formula / P or $ with i representing H or a C(O)OR group, and with Rf representing H, or a Ci-CiO alkyl group, the Ci-CiO alkyl group being unsubstituted or substituted by one or more, preferably one or two, Ci-C6 alkoxy, C2-C6 alkenyl, NRpiRP2, or NRpiRp2Rp3+X groups, with Rpb, Rp2, and Rp3 independently representing H or a Ci-C6 alkyl group and X representing a negatively charged counterion such as a halide, hydrogen sulfate (HSO4), or bisulfite (HSO3), the acrylic group being bonded 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): O (II), 9 (III), © (IV), qh RÆK zx A . RC. A. . R : OF< " ï If HO ' O ÿ in which: R represents H or a Ci-C6 alkyl, preferably H or a methyl, Rf and Rf independently represent H, a Ci-Cio alkyl, the Ci-Cio alkyl group being unsubstituted or substituted by a or

10.

11.

12.

13.

14.

15. several, preferably one or two, C1-C6 alkoxy, C2-C6 alkenyl, NRniRn2, or NRniRn2Rn3+X groups, with Rn[, 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). The composition according to claim 8 or 9, characterized in that compound M is present at a content 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. Composition according to any one of claims 1 to 10, characterized in that the photocurable 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 average number molar mass (Mn) is less than 10,000 g / mol, in particular less than or equal to 3,500 g / mol, preferably less than or equal to 3,000 g / mol; - its dispersity D (Mw / Mn) is less than 10, preferably less than or equal to 8, in particular less than or equal to 6. 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. A crosslinked composition obtained by crosslinking the photocrosslinkable composition according to any one of claims 1 to 11. 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. Use of the photocurable composition of any one of claims 1 to 11 for the preparation of products by 3D printing.