Method of preparation of a thermoplastic polymer by irradiation of a liquid composition

Abstract

The invention relates to a method for preparing a polymer (PA) comprising recurring units (RPA) derived from at least one monomer (M) of formula (I), where: • Z designates a-NH-C(=O)- group where NH is linked to either Alk1 or Alk2; • Alk1 and Alk2 designate independently a linear or branched C1-C15 alkylene group, the method comprising irradiating a composition (C) comprising monomer(s) (M).

Description

Method of preparation of a thermoplastic polymer by irradiation of a liquid compositionThis application claims priority of US provisional application N° 63 / 674,435 filed on 23 July 2024 and European patent application N° 24203792.7 filed on 1 October 2024, the content of which being entirely incorporated herein by reference for all purposes. In case of any incoherency between this application and one of the priority applications that would affect the clarity of a term or expression, it should be made reference to this application only.[TECHNICAL FIELD]

[0001] The present invention belongs to the technical field of photopolymerization, notably for the preparation of a three-dimensional object (hereinafter referred to as “3D object”).[TECHNICAL BACKGROUND]

[0002] Additive manufacturing (AM), also known as 3D printing, is a process used to fabricate a 3D object from a three-dimensional (3D) digital model, typically by laying down and bonding a large number of successive thin layers of material.

[0003] In recent years, 3D printing technologies have been used to produce a large number of items in a short period of time. For example, CN 106186810A discloses a 3D printing building materials and CN 105419306A discloses a 3D printed floor. There are several ways to build three-dimensional articles using photo-curable materials including stereolithography (SLA), digital light process (DLP), continuous liquid interface production (CLIP) and photopolymer jetting (PJ).

[0004] ACS Appl. Polym. Mater. 2019, 1 , 593-611 relates to 3D photopolymerization and discloses the techniques of 3D printing based on photopolymerization.

[0005] Vat photopolymerization (VP) is rapidly growing technology in the world of additive manufacturing. The resolution, print quality, and cost benefits provided by this approach relative to other techniques make it very attractive to commercial additive manufacturers and hobbyists. Currently, the vat photopolymerization (SLA, DLP, etc.) marketplace is dominated by amorphous thermoset materials, leaving a considerable performance gap in the resin offerings (tensile strength, impact strength, ductility, scratch and chemical resistance).

[0006] In a 3D printer using the DLP or SLA technology, the photo-curable material, which is in a liquid form, is layered on a vat or spread on a sheet, and a predetermined area or surface of the photo-curable material is exposed to ultraviolet-visible (UV / Vis) light that is controlled by a digital micro-mirror device or rotating mirror. Inthe DLP technology, additional layers are repeatedly or continuously laid, and each layer is cured until a desired 3D article is formed. The SLA technology is different from the DLP technology in that the liquid material is solidified by a line of radiation beam. Photopolymer jetting technology utilizes inkjet print heads to jet a liquid photopolymer which is immediately cured by a UV lamp and solidified to build layers on top of each other.

[0007] 3D-printing using photo-curable material has been adopted in many applications, e.g. rapid prototyping, manufacturing of hearing aids and other on-demand manufacturing. For example, WO 2014 / 172716A1 discloses the manufacturing of denture base and artificial teeth by using photo-curable liquid compositions and 3D-printing technology.

[0008] WO 2016153711A1 discloses a 3D-printing photo-curable composition comprising a photo-curable urethane acrylate / epoxy-based composition for a flexible materialbased object.

[0009] WO 2012 / 140194 A2 (D1) discloses a process for the production of a thermoplastic polymer containing carbon and sulphur in an atomic ratio of C : S of at least 4 and at most 36, wherein at most 70% of the protons are present as aromatic hydrogen atoms, the process comprising the step of step growth thiol-ene addition polymerization of at least one unsaturated thiol as monomer, thereby forming at least one thio ether function, optionally in a copolymerization with another monomer, pre-polymer or oligomer selected from homo and hetero pre-polymers and oligomers containing vinyl and / or thiol end groups, the unsaturated thiol monomer preferably being aliphatic and more preferably being obtained from a fatty acid. D1 discloses in examples 9-11 the synthesis of N-(2- mercaptoethyl)undec-10-enamide of formulaThe polymerization of this monomer was performed in the presence of LiBr (examples 12 and 13). The polymer prepared in D1 with this monomer thus contains lithium (and LiBr) as an impurity. Therefore, the polymer prepared in this example would require steps for removing Li and / or Br. For some application that requires, this impurity needs to be removed (see EP 0581386).

[0010] US 2022 / 315706 (D2) discloses a photopolymerization technique using a combination of two monomers of formulaand of x as RSBformula . The obtained polymer obtained by the thiol-ene reaction isof general formula: 0 o . See also Mater. Horiz.2020, 7, 835 (doi: 10.1039 / c9mh01336a).

[0011] Macromolecules 2014, 47, 61-69 discloses a polymer obtained by a thiol-ene reaction of formula:

[0012] Mendeleev Commun. 2022, 32, 231-233 discloses a 3D printing based on a UV- initiated thiol-ene polymerization.

[0013] US 2023 / 117061 discloses a photo-curable composition for 3D printing.

[0014] The regioselectivity of the addition of thiols to 1 -alkenes is documented in European Journal of Organic Chemistry 2018, ISSN: 1434-193X online ISSN: 1099-0690.

[0015] US 5,418,112 and US 5,545,367 disclose stereolithography.

[0016] Other printing techniques like selective laser sintering (SLS) and fused filament fabrication (FFF) which are capable of printing thermoplastic resins from intermediate forms (polymer powder & extruded filament) also exist on the market. A significant advantage of vat photopolymerization is that these expensive intermediate forms are not required. In fact, the “pre-resin” supplied for this technique is simply a formulation of photo-reactive monomers in liquid form.

[0017] Typically, these pre-resins are formulated from a moderately diverse set of multifunctional acrylate / methacrylate / epoxy monomers that are chosen and blended in ratios appropriate for the intended properties / application. A reasonably broad property space can be covered by formulating such pre-resins, and for the more high performance oriented products an additional ingredient for a dual-stage cure (UV + Heat) can be included to boost properties. Despite some of the innovative solutions in this space, the limitations of thermosets still exist and 3D printers that need / want thermoplastic properties are limited to SLS and FFF techniques. SLS requires intermediate powder form which creates difficulty and hazards during handling / use, in addition to the higher cost of the printing equipment. FFF, while less expensive on the equipment side, still requires expensive intermediate form and majority of cases does not achieve the near injection-molded equivalency that SLS can.[TECHNICAL PROBLEM]

[0018] The need exists of a photopolymerization technique using a low viscosity monomer in a liquid state to print in a fast way a 3D object made of a semi-crystallinethermoplastic polymer exhibiting good mechanical and dielectric properties and good thermal properties.

[0019] The polymerization should be fast enough to reach a high molecular weight in a short period of time. Moreover, the rate of polymerization should be higher than the rate of crystallization at a given temperature to avoid extinction of the polymerization and to allow printing to occur at a given temperature, before the material begins to crystallize and shrink, which could also lead to some distortion / warpage of the 3D object.

[0020] The composition used for the polymerization should also be fluid enough to be easily manipulated and to freely and quickly flow across the surface of the newly formed polymeric layer.

[0021] The invention aims at solving this technical problem.[BRIEF DISCLOSURE OF THE INVENTION!

[0022] The invention is disclosed in the present application, notably in the appended set of claims.

[0023] The invention relates to a photopolymerizarion process as disclosed in any one of claims 1-21.

[0024] The invention also relates to a polymer (PA) as disclosed in any one of claims 22- 44.

[0025] The invention also relates to a polymer composition (PC) as disclosed in any one of claims 45-46.

[0026] The invention also relates to a 3D object as disclosed in claim 47.

[0027] The invention also relates to a composition (C) as disclosed in any one of claims48-54.

[0028] The invention also relates to the use of composition (C) as disclosed in claim 55.

[0029] The invention also relates to a compound as disclosed in claims 56 or 57.

[0030] The invention also relates to the use of a compound as disclosed in claim 59.

[0031] More precisions and details about these subject-matters are now provided below.

[0032] wt.% is a percentage by weight. Mol.% is a percentage by mole.

[0033] Mn: number-average molecular weight; Mw: weight-average molecular weight.

[0034] When numerical ranges are given herein, unless otherwise expressly indicated, the end-points of the ranges (even in the open-ended ranges such as those comprising "at least", "at most", "lower than", "up to", etc or in ranges comprising “between") are included. The expression "at least" therefore corresponds to themathematical symbol > in the context of the present invention. The expression "at most" therefore corresponds to the mathematical symbol < in the context of the present invention. For clarity then, the ranges comprising the expression “between X and Y” are thus equivalent to “from X to Y”.

[0035] The proportions of recurring units in a polymer are expressed in mol% and given relative to the total amount of recurring units in said polymer.

[0036] In the present application, unless otherwise indicated, any specific embodiment or technical feature relating to one of the subject-matters of the invention is applicable to and interchangeable with another embodiment or technical feature relating also to said subject matter and disclosed elsewhere in the application. Likewise, unless otherwise indicated, any specific embodiment or technical feature relating to one of the subject-matters of the invention (e.g. method) is applicable to or interchangeable with another embodiment or technical feature (i) relating to another subject-matter (e.g. polymer) of the invention and (ii) disclosed elsewhere in the application.

[0037] As used herein, the terminology Cn-Cmin reference to an organic group or molecule, wherein n and m are integers, respectively, indicates that the group or molecule may contain from n carbon atoms to m carbon atoms per group, m and in included.

[0038] The term “alkylene" designates a divalent radical of formula -CnH2n- where n designates an integer > 1. In the context of the present invention, the alkylene is preferably a linear alkylene group. Linear alkylene groups are of formula -(CH2)n- where n designates an integer > 1 and represents the number of carbon atoms of the alkylene group, n is typically from 1 to 15. Examples of specific linear alkylene groups that can form part of the present invention are methylene -CH2-, ethylene -CH2CH2-, propylene -CH2CH2CH2- and butylene -CH2CH2CH2CH2- groups.

[0039] Fig. 1 / 3 represents a1H NMR spectrum of monomer M1 with Alki=-CH2- and Alk2=- (CH2)4-.

[0040] Fig. 2 / 3 represents a1H NMR spectrum of monomer M1 with Alki=-CH2- and Alk2=- (CH2)3-.

[0041] Fig. 3 / 3 represents a1H NMR spectrum of polymer obtained from the polymerization of a composition (C) comprising monomer M1 with Alki=-CH2- and Alk2=-(CH2)3-. After integration, one can calculate the proportion of recurring units RPA* = 9.9 mol% and RPA = 90.1 mol%.[DISCLOSURE OF THE INVENTION!

[0042] As a first aspect, the invention relates to a method for preparing a polymer (PA) comprising recurring units (RPA) derived from at least one monomer (M) of formula (I):where:• Z designates a -NH-C(=O)- group where NH is linked to either Alki or Alk2;• Alki and Alk2 designate independently a linear or branched C1-C15 alkylene group, wherein the method comprises irradiating a composition (C) comprising monomer(s) (M).

[0043] As a second aspect, the invention relates to a method of forming by additive manufacturing (AM) a 3D-object comprising a polymer (PA) comprising recurring units (RPA) derived from at least one monomer (M) of formula (I)where:• Z designates a -NH-C(=O)- group where NH is linked to either Alki or Alk2;• Alki and Alk2 designate independently a linear or branched C1-C15 alkylene group, the method comprising irradiating a composition (C) comprising monomer(s) (M).

[0044] This method includes stereolithography (SLA), digital light processing (DLP) or photopolymer jetting (PPJ) and other technique known by the skilled in the art.

[0045] Composition (C) is typically irradiated with a light having a wavelength between 100 and 700 nm, more particularly between 300 nm and 450 nm.

[0046] The intensity and duration of the light should generally be sufficient to trigger the polymerization of monomer(s) (M) and to reach a molecular weight sufficient for obtaining the requested mechanical properties of the polymer and for the dimensional stability of the 3D object. The intensity of the light is typically between 1.0 and 300.0 mW / cm2.

[0047] The temperature of composition (C) during irradiation is typically between 0°C and 150°C, preferably between 0°C and 100°C. This temperature can be between 0°C and 80°C.

[0048] Preferably, the method of the invention is stereolithography (SLA). Stereolithography is an additive manufacturing (AM) process that works byfocusing the light on a vat of composition (C) where polymerization of monomer (M) from composition (C) is triggered by the local irradiation to form a layer comprising polymer (PA) and the 3D object is prepared in a layer-by-layer fashion.

[0049] The invention also relates to the method for preparing a 3D object comprising polymer (PA) as defined herein, by photopolymerization, notably as defined in any one of claims 2-21 , the method comprising: a step (s) where a beam of light, typically a light having a wavelength from 100 to 700 nm, more particularly from 300 nm to 450 nm, is focused on the surface of a container filled with composition (C) as defined herein, the light beam, moving under computer control, and draws a layer of the 3D object onto the surface of the liquid after polymerization of monomer(s) (M); step (s) being repeated so that the object is built up layer by layer and the position of the object under construction being shifted typically downward in the container.

[0050] The motion of the beam across the surface is generally controlled by a computer.

[0051] When the 3D object is built, it is removed from the container.

[0052] The protocol disclosed in Chem. Mater. 2023, 35, 3825-3834 could be used after replacing the liquid disclosed in this publication by composition (C) according to the invention, notably a composition (C) with a molecule (M) as disclosed herein and a photoinitiator as disclosed herein, notably DPMA. The protocol disclosed in the article is based on a Flashforge Hunter DLP printer.

[0053] About monomer (M)

[0054] More details and embodiments relating to monomer (M) are disclosed below, all applicable to the subject-matters disclosed herein notably in the set of claims.

[0055] Monomer (M) is of formula (I):where:• Z designates a -NH-C(=O)- group where NH is linked to either Alki or Alk2;• Alki and Alk2 designate independently a linear or branched C1-C15 alkylene group, the method comprising irradiating a liquid composition (C) comprising monomer (M).

[0056] Alki and Alk2 designate independently a linear or branched C1-C15 alkylene group, more particularly a linear or branched C1-C10 alkylene group.

[0057] About Alki

[0058] According to an embodiment, Alki is a linear or branched C1-C7 alkylene group.

[0059] Alki is preferably a linear alkylene group.

[0060] According to an embodiment, Alki is -CH2-.

[0061] According to an embodiment, Alki is -CH2- and Alk2 is a C1-C10 linear alkylene group.

[0062] According to an embodiment, notably for (M2), Alki is a C1-C7 linear alkylene group.

[0063] According to an embodiment of the present invention, Alki is a C1-C7 or C9-C15 linear alkylene group, notably for monomer (M2).

[0064] According to an embodiment, Alki is any one of Alki disclosed in Table A below.

[0065] About Alk2

[0066] Alk2 is preferably a linear alkylene group.

[0067] According to an embodiment, Alk2 is any one of Alk2 disclosed in Table A below.

[0068] As mentioned above, the NH present in Z can be linked to either Alki or Alk2. Monomer (M) is therefore selected in the group of monomers (M1), (M2) and combination (M1) + (M2), where (M1) and (M2) are the following:

[0069] According to an embodiment, (M) is selected in the group of monomers (M1).According to an embodiment, (M) is selected in the group of monomers (M2).

[0070] According to an embodiment, (M) is selected in the group of monomers consisting of the monomers of Table A below (where M1 and M2 refer to the formulae above): Table A:

[0071] According to an embodiment, (M) is selected in the group of monomers consistingof monomer of formula monomer of formulaand combination of said two monomers.

[0001] According to an embodiment, monomer M is not monomer of type M2 with Alki=- (CH2)8- and Alk2=-(CH2)2-.

[0002] Preparation of monomers

[0003] Monomers (M1) and (M2) are prepared by a series of chemical reactions, typically involving as chemical product or intermediate a compound with a thiol group, where the thiol group is preferably protected during one or more of the chemical reactions.

[0004] Preparation of monomer (M1)

[0005] (M1) can be prepared by nucleophilic ring-opening reaction of an amine of formula CH2=CH-Alki-NH2with a thiolactone. The examples in the Experimental Section illustrates this chemical route.

[0006] Another general route to (M1) is disclosed in Scheme 1 below where Pr designatesH or a protective group of -SH group.Ml after deprotection if Pr HX= Cl, OH, OMeScheme 1

[0007] Scheme 1 discloses the reaction of a compound bearing an acyl group -C(=O)X with the compound of formula CH2=CH-Alki-NH2. M1 is obtained and if the thiolgroup is protected, the protective group needs to be removed according to well- known techniques of deprotection.

[0008] Preparation of monomer (M2)

[0009] Another general route to (M2) is disclosed in Scheme 2 below where Pr designates H or a protective group of -SH group. after deprotection if Pr HX= Cl, OH, OMeScheme 2

[0010] Scheme 2 discloses the reaction of a compound bearing the acyl group -C(=O)X with the compound of formula H2N-Alk2-SH. M2 is obtained and if the thiol group is protected, the protective group needs to be removed according to well-known techniques of deprotection.

[0011] In Scheme 1 and Scheme 2, X is more particularly Cl.

[0012] More details about polymer (PA) and composition (C) are provided below.

[0013] About polymer (PA)

[0014] More details and embodiments relating to polymer (PA) are disclosed below, all applicable to the subject-matters disclosed herein, notably in the set of claims.

[0015] Polymer (PA) is obtained by polymerization based on a thiol-ene radical addition.

[0016] Polymer (PA) typically comprises amide groups -NHCO- and -S- groups in its backbone.

[0017] Possibility exists that the thiol-ene reaction leads to some defects such as -S-S- bonds in polymer (PA).

[0018] According to an embodiment, polymer (PA) is prepared by the method of the invention, notably as disclosed in the claims.

[0019] Polymer (PA) comprises recurring units (RPA) of formula:where:• Z designates a -NH-C(=O)- group where the NH is linked to either Alki or Alk2;• Alki and Alk2 designate independently a linear or branched C1-C15 alkylene group.

[0020] These recurring units stem from monomer(s) (M).

[0021] According to an embodiment, Z is such that the NH is linked to Alki .

[0022] According to another embodiment, Z is such that the NH is linked to Alk2.

[0023] The proportion of recurring units (RPA) is typically at least 50.0 mol%, preferably at least 60.0 mol%, more preferably at least 70.0 mol%, even more preferably at least 80.0 mol%, even more preferably at least 88.0 mol%, this proportion being relative to the total proportion of recurring units of polymer (PA).

[0024] Polymer (PA) typically further comprises recurring units (RPA*) of formula:where Z is as disclosed herein.

[0025] Recurring units (RPA) and (RPA*) stem from monomer(s) (M). Z, Alki and Alk2 are therefore the same in (RPA) and in (RPA*).

[0026] All details and embodiments disclosed herein for the monomer, notably the details relating to Z, Alki and Alk2, apply similarly to recurring units (RPA) and (RPA*).

[0027] According to an embodiment of the present invention, the group -Alki-Z-Alk2- present in recurring units (RPA) and (RPA*) is selected in the group consisting of the groups disclosed in Table B herein [Alk2 being on the right handside].

[0028] The proportion of recurring units (RPA*) is typically at most 25.0 mol%, more preferably at most 20.0 mol%, even more preferably at most 15.0 mol%, this proportion being relative to the total proportion of recurring units of polymer (PA).

[0029] According to an embodiment, The proportion of recurring units (RPA*) is at most 12.0 mol%.

[0030] According to an embodiment, the proportion of recurring units in polymer (PA) are the following:(RPA); at least 80.0 mol%;(RPA*): at most 20.0 mol%. or the following:(RPA); at least 85.0 mol%;(RPA*): at most 15.0 mol%; or the following:(RPA); at least 88.0 mol%;(RPA*): at most 12.0 mol%.

[0031] Embodiment (E1)

[0032] According to an embodiment (E1), the recurring units of polymer (PA) consist essentially or consist of recurring units (RPA) and (RPA*). The expression “consist essentially" means in relation to the recurring units that the recurring units ofpolymer (PA) consist of recurring units (RPA), (RPA*) and up to 1.5 mol%, preferably up to 1.0 mol%, preferably up to 0.5 mol%, of recurring units other than (RPA) and (RPA*).

[0033] Embodiment (E2)

[0034] According to another embodiment (E2), polymer (PA) further comprises recurring units (RPA**) of formula:(RPA**) where:• R designates an alkylene of formula -CH2CH2- or -CH(Me)-;• G designates a divalent radical different of formula -G1-Z-G2- where Z is a -NH-C(=O)- group where NH is linked to either G1 or G2 and G1 and G2 are selected in the group consisting of (C1-C15) alkylene groups, (C1-C12) arylene groups, (C1-C12) cycloalkylene groups, (C1-C12) heteroarylene groups, (C1-C12) heterocycloalkylene groups with the proviso that at least one of G1 or G2 is a (C1-C15) alkylene group.

[0035] These units stem from a monomer having the following formula: H2C=CH-G-SH where G is as defined above.

[0036] Embodiment (E3)

[0037] According to an embodiment (E3), the recurring units of polymer (PA) consist essentially or consist of recurring units (RPA), (RPA*) and (RPA**). The expression “consist essentially" means in relation to the recurring units that the recurring units of polymer (PA) consist of recurring units (RPA), (RPA*), (RPA**) and up to 1.5 mol%, preferably up to 1.0 mol%, preferably up to 0.5 mol%, of recurring units other than (RPA), (RPA*) and (RPA**).

[0038] According to an embodiment of the present invention, notably applicable to embodiment (E1), (E2) or (E3), Z is such that NH is linked to Alki, Alki is CH2 and Alk2 is a C1-C10 linear alkylene group.

[0039] The recurring units of polymer (PA) disclosed above are preferably linked to one another by bonds linking a sulfur atom and a carbon atom.

[0040] The determination of the proportions of the recurring units in the polymer can be made with1H NMR spectroscopy. Fig. 3 / 3 illustrates the peaks of recurring units (RPA) (repeat unit A) and (RPA*) (repeat unit B) in the polymer obtained from a monomer (M1). The proportions of the repeat units A and B can be calculated after integration of specific peaks belonging to these repeat units [for instance, fromNMR spectrum of Fig. 3 / 3, one can use peak 8 which is linked to the -CH3 of repeat unit B / (RPA*) and peaks 2 and 6],

[0041] The proportions of the recurring units can also be determined after digestion of the polymer (PA), notably through cutting amide bonds -NHC(=O)- present in polymer (PA), and analysis of the mixture resulting from said digestion. Digestion is typically performed through bringing into contact polymer (PA) with a mineral acid such as HCI or HBr. The analysis of the mixture following the digestion is performed by the usual analytical techniques available to the skilled person. Gas chromatography (GO) and / or liquid chromatography (LG) can conveniently be used for this analysis.

[0042] Properties of polymer (PA)

[0043] The weight-average molecular weight (Mw) of polymer (PA) is preferably at least 3,000 g / mol, preferably at least 5,000 g / mol, more preferably at least 10,000 g / mol, more preferably at least 12,000 g / mol, even more preferably at least 20,000 g / mol. According to an embodiment, Mwis between 5,000 and 70,000 g / mol or between 10,000 and 70,000 g / mol or between 10,000 and 40,000 g / mol.

[0044] The number-average molecular weight (Mn) of polymer (PA) is preferably at least 5,000 g / mol, more preferably at least 6,000 g / mol. According to an embodiment, Mnis between 5,000 g / mol and 15,000 g / mol.

[0045] Mnand Mware determined by Size Exclusion Chromatography (SEC) (polymer in solution in 1 ,1 ,1 ,3,3,3-hexafluoropropan-2-ol with 0.05 mol / L sodium trifluoroacetate; standards used: PMMA)

[0046] Polymer (PA) is typically a semi-crystalline polymer.

[0047] Polymer (PA) is typically a linear polymer.

[0048] Glass transition temperature (Tq)

[0049] The glass transition temperature (Tg) of polymer (PA) is typically from -40.0 to 100.0°C, more particularly from -30.0°C to 70.0°C, more particularly from -30.0°C to 50.0°C.

[0050] Polymer (PA) preferably exhibits a glass transition temperature (Tg) of at least 30.0°C.

[0051] Melting temperature (Tm) and heat of fusion (Hm) of polymer (PA)

[0052] The melting temperature (Tm) of polymer (PA) is typically from 40.0 to 200.0°C, more particularly from 40.0°C to 150.0°C.

[0053] The heat of fusion (Hm) of polymer (PA) is typically from 10.0 J / g to 50.0 J / g, preferably from 20.0 J / g to 50.0 J / g, more preferably from 25.0 J / g to 50.0 J / g.

[0054] According to an embodiment, polymer (PA) exhibits the following thermal properties:- a melting temperature (Tm) of at least 100.0°C; and / or- a heat of fusion (Hm) of at least 25.0 J / g.

[0055] Polymer (PA) preferably exhibits the following thermal properties:- a melting temperature (Tm) of at least 130.0°C; and / or- a heat of fusion (Hm) of at least 30.0 J / g.

[0056] Tg, Tm and Hm are determined by Differential Scanning Calorimetry (DSC) according to ASTM D3418, notably according to protocol (p1) provided in the Experimental Section.

[0057] According to an embodiment, Tg, Tm and Hm are determined by Differential Scanning Calorimetry (DSC) according to protocol (p1) provided in the Experimental Section.

[0058] According to an embodiment, polymer (PA) is free of lithium. The expression "free of" in relation to Li means that the proportion of Li in polymer (PA) is lower than or equal to 500.0 ppm (< 500.0 ppm), preferably lower than or equal to 400.0 ppm (< 400.0 ppm), preferably lower than or equal to 300.0 ppm (< 300.0 ppm), preferably lower than or equal to 200.0 ppm (< 200.0 ppm), preferably lower than or equal to 100.0 ppm (< 100.0 ppm), preferably lower than or equal to 50.0 ppm (< 50.0 ppm), preferably lower than or equal to 10.0 ppm (< 10.0 ppm), lower than or equal to 5.0 ppm (< 5.0 ppm). The proportion of Li in polymer (PA) is determined by standard analytical techniques such as ICP-OES, notably on a solution obtained after ashing the sample in a furnace and adding nitric acid to the ashes. The proportion of Li in polymer (PA) can conveniently be determined by the method disclosed in the Experimental Section.

[0059] According to an embodiment of the present invention, polymer (PA) exhibits: a proportion of Li in polymer (PA) lower than or equal to 50.0 ppm; and / or a Mwof at least 3,000 g / mol, preferably at least 5,000 g / mol.

[0060] According to an embodiment of the present invention, polymer (PA) exhibits a proportion of Li < 10.0 ppm or < 5.0 ppm.

[0061] About composition (C)

[0062] The method of the invention is based on the irradiation of a composition (C) as defined herein.

[0063] More details and embodiments relating to composition (C) are disclosed below, all applicable to the subject-matters disclosed in the set of claims.

[0064] The invention also relates to a composition (C) comprising at least one monomer (M) as defined herein.

[0065] Composition (C) typically comprises, consists essentially of or consists of:- (i) at least one monomer (M) as defined herein;- (ii) at least one photoinitiator (P);- (iii) optionally at least one stabilizer (ST);- (iv) optionally at least one diluent (S).- (v) optionally at least one polymer additive (Add), notably selected in the group consisting of fillers, colorants, pigments, antioxidants, UV absorbers and combination thereof, and combination thereof.

[0066] According to an embodiment of the present invention, composition (C) comprises, consists essentially of or consists of:- (i) at least one monomer (M) as defined herein;- (ii) at least one photoinitiator (P);- (iii) at least one stabilizer (ST);- (iv) optionally at least one diluent (S).- (v) optionally at least one polymer additive (Add), notably selected in the group consisting of fillers, colorants, pigments, antioxidants, UV absorbers and combination thereof.

[0067] According to an embodiment, polymer additive (Add) is selected in the group consisting of fillers, colorants, pigments, antioxidants, UV absorbers and combination thereof, more particularly in the group consisiting of fillers, colorants, pigments and combination thereof.

[0068] According to an embodiment, composition (C) is free of lithium bromide. The expression "free of" in relation to LiBr means that the proportion of LiBr in composition (C) is lower than or equal to 0.15 wt% (< 0.15 wt%), preferably lower than or equal to 0.10 wt% (< 0.10 wt%), preferably does not comprise LiBr, this proportion being relative to the total weight of composition (C).

[0069] Details about the components of composition (C) are now disclosed below.

[0070] All details and embodiments disclosed herein and relative to monomer (M) are applicable to composition (C).

[0071] The proportion of monomer(s) (M) in composition (C) is typically at least 50.0 wt%, this proportion being relative to the total weight of composition (C). According to an embodiment of the present invention, this proportion is at least 75.0 wt% or at least 90.0 wt%.

[0072] Composition (C) is typically liquid.

[0073] Photoinitiator (P)

[0074] At least one photoinitiator (P) is typically present in the composition (C). A photoinitiator refers to a compound that converts the photolytic energy of the radiation used into reactive species, such as radical species.

[0075] Photoinitiator (P) is typically a free radical photoinitiator.

[0076] Photoinitiator (P) is generally selected from the group consisting of phosphine oxides, organometallics, benzophenones, thioxanthones, phosphinates, hydroxy ketones and combinations thereof.

[0077] In the context of the present invention, photoinitiator (P) is more particularly selected in the group consisting of acetophenone, anisoin, anthraquinone, anthraquinone-2-sulfonic acid, sodium salt monohydrate (benzene) tricarbonylchromium, benzil, benzoin, benzoin ethyl ether, benzoin isobutyl ether, benzoin methyl ether and benzophenone 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4-benzoylbiphenyl, 2-benzyl-2-(dimethylamino)-4'- morpholinobutyrophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'- bis(dimethylamino)benzophenone, camphorquinone, 2-chlorothioxanthen-9-one, (cumene)cyclopentadienyl iron(ll) hexafluorophosphate, dibenzosuberenone, 2,2- diethoxyacetophenone, 4,4'-dihydroxybenzophenone; 2,2-dimethoxy-2- phenylacetophenone, 4-(dimethylamino)benzophenone, 4,4'-dimethylbenzil, 2,5- dimethylbenzophenone, 3,4-dimethylbenzophenone, diphenyl(2,4,6- trimethylbenzoyl)phosphine oxide, 2-hydroxy-2-methylpropiophenone, blends of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and 2-hydroxy-2-methyl-1- phenyl-propan-1-one, blends of ethyl phenyl(2,4,6- trimethylbenzoyl)phosphinate and phenyl bis(2,4,6-trimethylbenzoyl)-phosphine oxide, 4'-ethoxyacetophenone, 2-ethylanthraquinone, ferrocene, 3'-hydroxyacetophenone, 4'- hydroxyacetophenone, 3-hydroxybenzophenone, 4-hydroxybenzophenone, 1- hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2- methylbenzophenone, 3-methylbenzophenone, methybenzoylformate, 2-methyl- 4'-(methylthio)-2-morpholinopropiophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2- methylpropiophenone, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, phenanthrenequinone, 4'-phenoxyacetophenone, phenylbis(2,4,6- trimethylbenzoyl)phosphine oxide, thioxanthen-9-one, 2-isopropylthioxanthone, triarylsulfonium hexafluoroantimonate salts, triarylsulfonium hexafluorophosphate salts, 2,4,5,7-tetraiodo-3-hydroxy-9-cyano-6-fluorone, 2,4,5,7-tetraiodo-3- hydroxy-6-fluorone, 5,7-diiodo-3-butoxy-6-fluorone and mixtures thereof.

[0078] Photoinitiator (P) is more particularly selected in the group consisting of benzoin methyl ether, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, benzil dimethyl ketal, 1 -hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2- morpholinopropan-1-one, ethyl 2,4,6-trimethylbenzoylphenylphosphinate, camphorquinone and methylene blue.

[0079] Photoinitiator (P) is preferably a molecule which does not comprise at least one element selected in the group consisting of Cr and Fe.

[0080] According to an embodiment, photoinitiator (P) is any one of the photoinitiators disclosed herein.

[0081] According to an embodiment, photoinitiator (P) is 2,2-dimethoxy-2- phenylacetophenone (DPMA).

[0082] According to an embodiment of the present invention, composition (C) comprises only one photoinitiator (P).

[0083] Photoinitiator (P) preferably exhibits a maximum wavelength absorbance between 200 nm and 400 nm, preferably between 300 and 400 nm.

[0084] The proportion of photoinitiator(s) (P) in composition (C) is preferably between 0.1 and 5.0 mol%, this proportion being expressed relative to the total proportion of monomer(s) (M).This proportion is typically between 0.5 and 3.0 mol% or between 0.7 and 1.3 mol%, this proportion being expressed relative to the total proportion of monomer(s) (M).

[0085] Stabilizer (ST)

[0086] At least one stabilizer (ST) may also be present in composition (C). A stabilizer is a compound used to prevent auto-reaction of the monomer(s) in the composition (C). For instance, the presence of (hydro) peroxide impurities may be responsible for such auto-reaction of the monomer(s).

[0087] The stabilizer (ST) may be present in the monomer (M) to stabilize it.

[0088] The stabilizer (ST) may be selected in the group consisting of the following compounds:

[0089] The stabilizer (ST) may be combined with an acidic compound to increase its efficiency. The acidic compound may be selected in the group of BSA, BA and PPA:PP* A = PO3H2

[0090] The stabilizer (ST) is more particularly pyrogallol, optionally combined with phenylphosphonic acid as an acidic compound.

[0091] The proportion of stabilizer(s) (ST) in composition (C) is preferably between 0.1 and 5.0 mol% relative to the monomer(s). This proportion is typically between 0.5and 3.0 mol% relative to the monomer(s). This proportion does not takes into account only the proportion of acidic compound(s) that may be used in combination with the stabilizer(s).

[0092] Composition (C) may also comprise at least one diluent (S). The function of the diluent is to dissolve a component of the composition (C) and / or to decrease the viscosity of composition (C). The diluent may be selected in the group consisting of dimethyl sulfoxide, dimethylformamide, dimethylacetamide, molecule of formula MeOOC-A1-CONMe2 where A1 is -CHMe-CH2CH2- linked to the ester and / or amide group, acetonitrile, sulfolane, N-methyl pyrrolidone, an alcohol, a ketone or a mixture thereof.

[0093] Composition (C) may also comprise at least one polymer additive (Add). After the photopolymerization, the additive(s) remain(s) partly or totally in polymer (PA)

[0094] To be noted, composition (C) may further comprise other components to modify the physico-chemical properties of the composition (C) or of the polymer (PA). For instance, composition (C) may comprise a viscosity modifier to modify the viscosity of the composition. As another example, composition (C) may comprise a crosslinker.

[0095] Polymer composition (PC)

[0096] As a third aspect, the invention also relates to a polymer composition (PC) comprising or consisting of:- at least one polymer (PA) as disclosed herein;- optionally at least one polymer additive (Add), notably selected in the group consisting of fillers, colorants, pigments, antioxidants, UV absorbers and combination thereof.

[0097] The proportion of polymer(s) (PA) is typically at least 30.0 wt%, this proportion being relative to the total weight of composition (PC). This proportion is typically from 30.0 to 100 wt%.

[0098] Polymer composition (PC) can be prepared by the method of the invention.

[0099] Polymer composition (PC) may also be prepared by a method comprising a step in which the components of the polymer composition (PC) are introduced into a mixer, such as single screw extruder or twin screw extruder, agitator, single screw or twin screw kneader or an internal mixer that comprises two rotors enclosed in a mixing chamber (e.g. a Banbury mixer) wherein the polymeric component of the polymer composition (PC) is in the molten form. The mixer is conveniently an extruder.

[0100] 3D object

[0101] As another aspect, the invention also relates to a 3D object prepared by the method of the invention and / or comprising the polymer (PA) of the invention.

[0102] Use

[0103] As another aspect, the invention also relates to the use of the composition (C) of the invention in a photopolymerization process.

[0104] Compound

[0105] As another aspect, the invention also relates to a compound of formula (I) (or monomer M)) as disclosed herein. All details and embodiments disclosed herein

[0106] As another aspect, the invention also to the use of compound of formula (I) (or monomer M)) as disclosed herein for the preparation of a polymer by a photopolymerization process, notably a 3D photopolymerization process, the polymer being notably polymer (PA) as disclosed herein.[Experimental section]

[0107] The disclosure is further described in detail by reference to the following experimental examples. These examples are provided for purposes of illustration only and are not intended to be limiting unless otherwise specified. Thus, the disclosure should in no way be construed as being limited to the following examples, but rather, should be construed to encompass any and all variations which become evident as a result of the teaching provided herein.

[0108] Chemical products used

[0109] Conditions of DSC for determining the thermal properties of the polymer protocol (p1)

[0110] Conditions of size exclusion chromatography (SEC)

[0111] Mobile Phase: hexafluoroisopropanol with 0.05 mol / l sodium trifluoroacetate.

[0112] Calibration: standard calibration using PMMA standards.

[0113] Measurement of lithium and LiBr content by ICP-OES (Inductively Coupled Plasma - Optical Emission Spectroscopy)

[0114] Desired amount of sample is placed into a platinum crucible and ashed in a muffle furnace, ramping up to 525 °C and sitting for 10 hours. 10-mL of water and 1-mL of nitric acid are added to the crucible once ashing is complete. Sample is then extracted into a 25-mL volumetric flask and inverted. Sample is transferred to a centrifuge tube and placed in the ICP-OES autosampler for analysis. The lithium method for ICP-OES analysis is as follows: calibration curve is generated by using blank, 1 ppm, 5 ppm, and 20 ppm standards. Lithium 670.784 nm wavelength is used for analysis on radial viewing mode.[00115

[0116] To an oven dried single-neck 25 mL round bottom flask equipped with a magnetic stir bar is added gamma-butyrothiolactone (10.00 g, 0.097 mol, 1.00 equivalent), allylamine (6.43 g, 0.113 mol, 1.15 equivalents) and pyrogallol (61.7 mg, 0.489 mmol, 0.05 equivalents. The flask is sealed with a rubber septum and positioned above a magnetic stir plate and stirring is commenced. At this time a nitrogen purge is introduced via a needle through the septum and allowed purge for 1 minute before removing the needle and leaving the flask with a nitrogen atmosphere. The resulting clear colorless solution is allowed to stir for 3 hours at room temperature during which the flask is wrapped with aluminum foil to protect from light. After 3 hours of stirring, the flask is assembled into a short-path distillation there theexcess reactant is removed at room temperature using high vacuum (0.1 mBar) for approximately 12 hours. Following the overnight distillation, phenylphosphonic acid (78.3 mg, 0.489 mmol, 0.05 equivalents) is added to the resulting oil and swirled to dissolve over a 10 minute period. The final product is a clear colorless oil (15.496 g, 99% yield). Melting point: -7 °C. Viscosity: 30 cP at 25 °C, measured using Brookfield rotational viscometer. As can be seen, this monomer exhibits a low viscosity.

[0117] Preparation of monomer type M1 with Alki=-CH2- and Alk2=-(CH2)4-

[0118] To an oven dried single-neck 25 mL round bottom flask equipped with a magnetic stir bar is added tetrahydro-2H-thiopyran-2-one (5.00 g, 0.043 mol, 1.00 equivalent), allylamine (2.826 g, 0.050 mol, 1.15 equivalents), and pyrogallol (27.1 mg, 0.215 mmol, 0.05 equivalents. The flask is sealed with a rubber septum and positioned above a magnetic stir plate and stirring is commenced. At this time a nitrogen purge is introduced via a needle through the septum and allowed purge for 1 minute before removing the needle and leaving the flask with a nitrogen atmosphere. The resulting clear colorless solution is allowed to stir for 3 hours at room temperature during which the flask is wrapped with aluminum foil to protect from light. After 3 hours of stirring, the flask is assembled into a short-path distillation there the excess reactant is removed at room temperature using high vacuum (0.1 mBar) for approximately 12 hours. Following the overnight distillation, phenylphosphonic acid (34.4 mg, 0.215 mmol, 0.05 equivalents) is added to the resulting oil and swirled to dissolve over a 10 minute period. The final product is a clear colorless oil (6.802 g, 91% yield). Melting point: 8 °C. Viscosity: 45 cP at 25 °C, measured using a Brookfield rotational viscometer. As can be seen, this monomer exhibits a low viscosity.

[0119] Preparation of undec- 10-enoyl chloride

[0120] To an oven dried three-neck round bottom flask equipped with a magnetic stir bar is added undec- 10-enoic acid (5.0285 g, 27.287 mmol, 1.00 equivalent). The flask is sealed with a rubber septum, a condenser with 5 °C water flow is added to the second neck, and an addition funnel is added to the final neck. The condenser and addition funnel are also capped with rubber septa. The apparatus was cycled between dry N2 and vacuum 4 times and was left under N2. A needle connected toan oil bubbler was added to the septa above the condenser and the flask was lowered into an oil bath at 75 °C. Once the mixture was molten vigorous stirring was applied using a magnetic stir plate. Dimethylformamide (100 pL) was added via syringe into the undec- 10-enoic acid while oxalyl chloride (14 mL, 163 mmol, 6 equivalents) was added to the addition funnel. Oxalyl chloride was then added to the undec- 10-enoic acid dropwise over the course of 45 minutes. The solution was then brought to reflux and held for two hours. Once complete, the flask was removed from the oil bath but stirring was maintained. The flask was then placed under vacuum to remove the excess of oxalyl chloride and was held under vacuum for 2 hours. Remaining in the flask was an orange-brown solution with some tar precipitate that consisted of undec- 10-enoyl chloride, which was used without further purification.

[0121] Preparation of monomer type M2 with Alki=-(CH2)s- and Alk2=-(CH2)2-

[0122] To prepare the N-(2-mercaptoethyl)undec-10-enamide, cysteamine (3.273 g, 42.43 mmol, 1 .55 equivalents) and a magnetic stir bar was added to an oven-dried two-neck round bottom flask with water jacket under inert conditions. A rubber septum was placed on one of the two necks and a capped addition funnel was placed on the second. The flask was then cycled 4x between dry N2and vacuum, leaving under N2atmosphere. A needle connected to an oil bubbler was then added to the septa and the jacket was connected to 0°C recirculating water. The cysteamine was then dissolved in 380 mL of dry dichloromethane with vigorous stirring. Dry triethylamine (6 mL, 43 mmol, 1.58 equivalents) was added to the flask via syringe and was rinsed with additional dry DCM. The undec-10-enoyl chloride was added to the addition funnel and the reaction flask was washed 2x with additional dry dichloromethane (DCM). The undec- 10-enoyl chloride was added dropwise to the cysteamine solution over the course of 1 hour, and the addition funnel was rinsed with additional dry DCM. After addition, the flask was allowed to stir for an additional hour before the apparatus was disassembled. The solution was a bright yellow coloration with no precipitate. The reaction mixture was then washed twice with 1 N aqueous HCI, dried with sodium sulfate, and evaporated to dryness. Remaining in the flask was a yellow waxy substance, the impure N-(2- mercaptoethyl)undec-10-enamide. The impure N-(2-mercaptoethyl)undec-10- enamide was purified by recrystallization from methanol. The crude mixture was dissolved in minimal boiling methanol before wrapping in insulation to slowly cool. Once the solution reached room temperature, the flask was placed in a lab fridgeat 36 °F for one hour. Afterwards the crystals were isolated from the solution by vacuum filtration, yielding pure N-(2-mercaptoethyl)undec-10-enamide.

[0123] Conversion of °F into °C: (32 °F - 32) x 5 / 9

[0124] Examples of polymerization according to the invention

[0125] Table I: E1 and E2 are based on monomer M1 with Alki=-CH2- and Alk2=-(CH2)3-. E3 and E4 are based on monomer M1 with Alki=-CH2- and Alk2=-(CH2)4-. E5 and E6 are based on a mixture of two monomers M1 with Alki=-CH2- and Alk2=-(CH2)3- and with Alki=-CH2- and Alk2=-(CH2)4-.

[0126] Table II: E7-E9 are based on monomer M2 with Alki=-(CH2)s- and Alk2=-(CH2)2- with or without presence of LiBr.

[0127] Table III: E10-E12 are based on monomer M2 with Alki=-(CH2)2- and Alk2=-(CH2)2.

[0128] Example E1 :

[0129] To a 20 mL dram vial was added “AB Monomer” N-allyl-4-mercaptobutanamide (1.000 g, 6.28 mmol, 1.00 equivalent), and “DMPA” 2,2-dimethoxy-2- phenylacetophenone (16.1 mg, 0.063 mmol, 0.01 equivalents). The vial was swirled at room temperature to dissolve for approximately 10 minutes. The clear colorless oil was pipetted atop a flat surface at room temperature where it was irradiated for 5 minutes with 90 mW / cm2of unfiltered UV light from an OmniCure S2000 light source (this sources emits in a range of wavelengths between 250 and 600 nm). The resulting solid / flexible disc was delaminated from the surface.

[0130] Examples E2-E6

[0131] A similar method to that described in Example 1 was applied to examples 2 through 6, with the exception that Examples E2, E4, and E6 were heated to 70 °C.

[0132] The proportion of photoinitiator (DMPA) is around 1 mol%.

[0133] As can be seen, it is possible to photopolymerize monomers M1 and / or M2 in order to prepare a thermoplastic polymer (PA). The copolymerization induces a lowering of the melting temperature and of the crystallinity. Moreover, it is observed that increasing the temperature from 0°C to 70°C leads to higher molecular weights without deteriorating the thermal properties.

[0134] Example E7:

[0135] To a 20 mL dram vial was added N-(2-mercaptoethyl)undec-10-enamide (180 mg, 0.74 mmol, 1.00 equivalents), and “DMPA” 2,2-dimethoxy-2-phenylacetophenone (7.6 mg, 0.030 mmol, 4 mol%). The mixture was dissolved in dry diethyl ether and allowed to mix for 10 minutes. After dissolution the ether was removed by placing under high vacuum for ~12 hours. The monomer powder was placed atop a flat surface at 100°C to melt. Once fully molten it was irradiated for 10 minutes with 20-25 mW / cm2of UV light from an Analytik jena UVP BLAK-RAY B-100AP LAMP(100W365 nm longwave) lamp. The material was cooled before delaminating from the surface for analysis.

[0136] Example E8:

[0137] A flat-bottom test tube with ground glass joint was suspended above a magnetic stir plate and a UV lamp (Analytik jena UVP BLAK-RAY B-100AP LAMP (100W 365 nm longwave)) was aimed at the base of the tube. The light intensity was calibrated by measurement (Silver Line UV Radiometer (230 - 410 nm)) through the test tube to ensure sufficient intensity was achieved in the solution. Light intensity was determined to be 12-20 mW / cm2after passing through the tube. A solution of N-(2-mercaptoethyl)undec-10-enamide, “DM PA” 2,2-dimethoxy-2- phenylacetophenone (4 mol%), and lithium bromide (5 wt% of monomer) was prepared by dissolving in minimal dry, degassed THF. After full dissolution and time to allow the lamp to warm up, the solution was transferred to the test tube with a magnetic stir bar set to vigorous stirring. The test tube was capped, and the solution was allowed to polymerize for 2 hours, yielding a viscous polymer solution. The polymer was then precipitated from methanol. The white, crystalline polymer was then isolated by vacuum filtration and dried under vacuum before additional analysis.

[0138] Example E9:

[0139] A flat-bottom test tube with ground glass joint was suspended above a magnetic stir plate and a UV lamp (Analytik jena UVP BLAK-RAY B-100AP LAMP (100 W 365 nm longwave)) was aimed at the base of the tube. The light intensity was calibrated by measurement (Silver Line UV Radiometer (230 - 410 nm)) through the test tube to ensure sufficient intensity was achieved in the solution. Light intensity was determined to be 12-20 mW / cm2after passing through the tube. A solution of N-(2-mercaptoethyl)undec-10-enamide, “DM PA” 2,2-dimethoxy-2- phenylacetophenone (4 mol%), and lithium bromide (5 wt% of total solution including THF) was created by dissolving in minimal dry, degassed THF. After full dissolution and time to allow the lamp to warm up, the solution was transferred to the test tube with a magnetic stir bar set to vigorous stirring. The test tube was capped, and the solution was allowed to polymerize for 2 hours, yielding a viscous polymer solution. The polymer was then precipitated from methanol. The white, crystalline polymer was then isolated by vacuum filtration and dried under vacuum before additional analysis.

[0140] Polymerizations with lithium bromide as an additive (E8 & E9) require additional steps to remove lithium / lithium bromide from the polymer (PA). Moreover, polymer prepared in a neat system without LiBr (E7), a loss of crystallinity was observed.

[0141] Example E10-E12

[0142] These examples are summarized in Table III.Table IIITableTable

Claims

ClaimsClaim 1. A method for preparing a polymer (PA) comprising recurring units (RPA) derived from at least one monomer (M) of formula (I):where:• Z designates a -NH-C(=O)- group where NH is linked to either Alki or Alk2;• Alki and Alk2 designate independently a linear or branched C1-C15 alkylene group, the method comprising irradiating a composition (C) comprising monomer(s) (M), composition (C) being preferably irradiated with a light having a wavelength between 100 and 700 nm, more particularly between 300 nm and 450 nm.Claim 2. A method of forming by additive manufacturing (AM) a 3D-object comprising a polymer (PA) comprising recurring units (RPA) derived from at least one monomer (M) of formula (I)where:• Z designates a -NH-C(=O)- group where NH is linked to either Alki or Alk2;• Alki and Alk2 designate independently a linear or branched C1-C15 alkylene group, the method comprising irradiating a composition (C) comprising monomer(s) (M), composition (C) being preferably irradiated with a light having a wavelength between 100 and 700 nm, more particularly between 300 nm and 450 nm.Claim 3. Method according to any one of the preceding claims, wherein monomer (M) is selected in the group of monomers (M1), (M2) and combination (M1) + (M2), where (M1) and (M2) are the following:Claim 4. Method according to any one of the preceding claims, wherein polymer (PA) comprises recurring units (RPA) of formula:where Z, Alki and Alk2 are as defined in any one of the preceding claims, the proportion of recurring units (RPA) being preferably at least 50.0 mol%, preferably at least 60.0 mol%, more preferably at least 70.0 mol%, even more preferably at least 80.0 mol%, this proportion being relative to the total proportion of recurring units of polymer (PA).Claim 5. Method according to claim 4, wherein the proportion of (RPA) is at least 88.0 mol%.Claim 6. Method according to claim 4 or 5, wherein polymer (PA) further comprises recurring units (RPA*) of formula:where Z, Alki and Alk2 are as in (RPA), the proportion of which being preferably at most 25.0 mol%, preferably at most 20.0 mol%, more preferably at most 15.0 mol%, this proportion being relative to the total proportion of recurring units of polymer (PA).Claim 7. Method according to claim 6, wherein the proportion of (RPA*) is at most 12.0 mol%.Claim 8. Method according to claim 6, wherein the proportion of recurring units in polymer (PA) are the following:(RPA); at least 80.0 mol%;(RPA*): at most 20.0 mol%. or the following:(RPA); at least 85.0 mol%;(RPA*): at most 15.0 mol%; or the following:(RPA); at least 88.0 mol%;(RPA*): at most 12.0 mol%.Claim 9. Method according to any one of claims 6-8, wherein the recurring units of polymer (PA) consist of or consists essentially of recurring units (RPA) and (RPA*), where the expression “consist essentially" means in relation to the recurring units that the recurring units of polymer (PA) consist of recurring units (RPA), (RPA*) and up to 1.5 mol%, preferably up to 1.0 mol%, preferably up to 0.5 mol%, of recurring units other than (RPA) and (RPA*).Claim 10. Method of any one of claims 4-9, wherein polymer (PA) further comprises recurring units (RPA**) of formula:(RPA**) where:• R designates an alkylene group of formula -CH2CH2- or -CH(Me)-;• G designates a divalent radical of formula -G1-Z-G2- where Z is a -NH- C(=O)- group where NH is linked to either G1 or G2 and G1 and G2 are selected in the group consisting of (C1-C15) alkylene groups, (C1-C12) arylene groups, (C1-C12) cycloalkylene groups, (C1-C12) heteroarylene groups, (C1-C12) heterocycloalkylene groups with the proviso that at least one of G1 or G2 is a (C1-C15) alkylene group.Claim 11. Method according to any one of the preceding claims, wherein polymer (PA) is a semi-crystalline polymer, notably exhibiting the following thermal properties:- a melting temperature (Tm) of at least 100.0°C; and / or- a heat of fusion (Hm) of at least 25.0 J / g; or the following ones:- a melting temperature (Tm) of at least 130°C; and / or- a heat of fusion (Hm) of at least 30.0 J / g; these properties being measured according to ASTM D3418 or as measured in protocol (p1) of the Experimental Section.Claim 12. Method according to any one of the preceding claims, wherein composition (C) comprises, consists essentially of or consists of:- (i) at least one monomer (M);- (ii) at least one photoinitiator (P), notably selected in the group consisting of phosphine oxides, benzophenones, thioxanthones, phosphinates, hydroxyketones and combinations thereof; (P) being more particularly selected in the group consisting of acetophenone, anisoin, anthraquinone, anthraquinone-2- sulfonic acid, sodium salt monohydrate (benzene) tricarbonylchromium, benzil, benzoin, benzoin ethyl ether, benzoin isobutyl ether, benzoin methyl ether and benzophenone 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4- benzoylbiphenyl, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, 4,4'- bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, camphorquinone, 2-chlorothioxanthen-9-one, (cumene)cyclopentadienyl iron(ll) hexafluorophosphate, dibenzosuberenone, 2,2-diethoxyacetophenone, 4,4'- dihydroxybenzophenone; 2,2-dimethoxy-2-phenylacetophenone, 4- (dimethylamino)benzophenone, 4,4'-dimethylbenzil, 2,5-dimethylbenzophenone, 3,4-dimethylbenzophenone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 2- hydroxy-2-methylpropiophenone, blends of bis(2,4,6-trimethylbenzoyl)- phenylphosphine oxide and 2-hydroxy-2-methyl-1- phenyl-propan-1-one, blends of ethyl phenyl(2,4,6- trimethylbenzoyl)phosphinate and phenyl bis(2,4,6- trimethylbenzoyl)-phosphine oxide, 4'-ethoxyacetophenone, 2- ethylanthraquinone, ferrocene, 3'-hydroxyacetophenone, 4'- hydroxyacetophenone, 3-hydroxybenzophenone, 4-hydroxybenzophenone, 1- hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2- methylbenzophenone, 3-methylbenzophenone, methybenzoylformate, 2-methyl- 4'-(methylthio)-2-morpholinopropiophenone, 2-hydroxy-4'-(2-hydroxyethoxy)-2- methylpropiophenone, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, phenanthrenequinone, 4'-phenoxyacetophenone, phenylbis(2,4,6- trimethylbenzoyl)phosphine oxide, thioxanthen-9-one, 2-isopropylthioxanthone, triarylsulfonium hexafluoroantimonate salts, triarylsulfonium hexafluorophosphate salts, 2,4,5,7-tetraiodo-3-hydroxy-9-cyano-6-fluorone, 2,4,5,7-tetraiodo-3- hydroxy-6-fluorone, 5,7-diiodo-3-butoxy-6-fluorone and mixtures thereof;- (iii) optionally at least one stabilizer (ST), notably being any one of the stabilizers disclosed herein, optionally in combination with at least one acidic compound;- (iv) optionally at least one diluent (S);- (v) optionally at least one polymer additive (Add), notably selected in the group consisting of fillers, colorants, pigments, antioxidants, UV absorbers and combination thereof.Claim 13. Method according to claim 12, wherein photoinitiator (P) is selected in the group consisting of benzoin methyl ether, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, benzil dimethyl ketal, 1 -hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, ethyl 2,4,6-trimethylbenzoylphenylphosphinate, camphorquinone and methylene blue; more particularly photoinitiator (P) is 2,2-dimethoxy-2- phenylacetophenone (DPMA).Claim 14. Method according to claim 12 or 13, wherein composition (C) comprises only one photoinitiator (P).Claim 15. Method according to any one of claims 12-14, wherein polymer additive (Add) is selected in the group consisting of fillers, colorants, pigments and combination thereof.Claim 16. Method according to any one of the preceding claims, wherein composition (C) is free of lithium bromide, the expression "free of" meaning that the proportion of LiBr in composition (C) is lower than or equal to 0.15 wt% (< 0.15 wt%), preferably lower than or equal to 0.10 wt% (< 0.10 wt%), preferably does not comprise LiBr, this proportion being relative to the total weight of composition (C).Claim 17. Method according to any one of the preceding claims, wherein the proportion of monomer(s) (M) in composition (C) is: at least 50.0 wt%; or at least 75.0 wt%; or at least 90.0 wt%; this proportion being relative to the total weight of composition (C).Claim 18. Method according to any one of the preceding claims, wherein Alki and Alk2 designate independently: a linear or branched C1-C10 alkylene group; or a linear or branched C1-C7 alkylene group.Claim 19. Method according to any one of the preceding claims, wherein Alki is -CH2- and Alk2 is:- a C1-C10 linear alkylene group; or- a C1-C7 linear alkylene group.Claim 20. Method according to any one of the preceding claims, wherein monomer (M) is selected in the group consisting of the molecules of Table A below:Table A:where M1 and M2 are as defined in claim 3.Claim 21. Method according to any one of the preceding claims, wherein monomer (M) is not monomer of type M2 with Alki=-(CH2)s- and Alk2=-(CH2)2-, where M2 is as defined in claim 3.Claim 22. Polymer (PA) prepared by the method of any one of claims 1-21 , this polymer notably comprising comprises amide groups -NHCO- and -S- groups in its back-bone. Claim 23. Polymer (PA), notably according to claim 22, comprising at least 50.0 mol%, preferably at least 60.0 mol%, preferably at least 70.0 mol%, preferably at least 80.0 mol%, this proportion being relative to the total proportion of recurring units of polymer (PA).where:Z designates a -NH-C(=O)- group where NH is linked to either Alki or Alk2;• Alki and Alk2 designate independently a linear or branched C1-C15 alkylene group.Claim 24. Polymer (PA) according to claim 23, wherein the proportion of (RPA) is at least 88.0 mol%.Claim 25. Polymer (PA) according to claim 22 or 23, wherein polymer (PA) further comprises recurring units (RPA*) of formula:where Z, Alki and Alk2 are as in (RPA), the proportion of which being preferably at most 25.0 mol%, preferably at most 20.0 mol%, more preferably at most 15.0 mol%, this proportion being relative to the total proportion of recurring units of polymer (PA).Claim 26. Polymer (PA) according to claim 25, wherein wherein the proportion of (RPA*) is at most 12.0 mol%.Claim 27. Polymer (PA) according to claim 25 or 26, wherein the proportion of recurring units in polymer (PA) are the following:(RPA); at least 80.0 mol%;(RPA*): at most 20.0 mol%. or the following:(RPA); at least 85.0 mol%;(RPA*): at most 15.0 mol%.Claim 28. Polymer (PA) according to any one of claims 25-27, wherein the recurring units of polymer (PA) consist of or consists essentially of recurring units (RPA) and (RPA*), where the expression “consist essentially" means in relation to the recurring units that the recurring units of polymer (PA) consist of recurring units (RPA), (RPA*) and up to 1.5 mol%, preferably up to 1 .0 mol%, preferably up to 0.5 mol%, of recurring units other than (RPA) and (RPA*).Claim 29. Polymer (PA) according to any one of claims 22-28, wherein polymer (PA) further comprises recurring units (RPA**) of formula:(RPA**)where:• R designates an alkylene group of formula -CH2CH2- or -CH(Me)-;• G designates a divalent radical of formula -G1-Z-G2- where Z is a -NH- C(=O)- group where NH is linked to either G1 or G2 and G1 and G2 are selected in the group consisting of (C1-C15) alkylene groups, (C1-C12) arylene groups, (C1-C12) cycloalkylene groups, (C1-C12) heteroarylene groups, (C1-C12) heterocycloalkylene groups with the proviso that at least one of G1 or G2 is a (C1-C15) alkylene group.Claim 30. Polymer (PA) according to any one of claims 23-29, wherein Alki and Alk2 designate independently: a linear or branched C1-C10 alkylene group; or a linear or branched C1-C7 alkylene group.Claim 31. Polymer (PA) according to any one of claims 23-30, wherein wherein Alki is - CH2- and Alk2 is:- a C1-C10 linear alkylene group; or- a C1-C7 linear alkylene group.Claim 32. Polymer (PA) according to any one of claims 23-30, wherein Alki is a C1-C7 or C9-C15 linear alkylene group, notably for monomer (M2).Claim 33. Polymer (PA) according to any one of claims 23-32, wherein recurring units (RPA) and (RPA*) are characterized by one of the groups -Alki-Z-Alk2- as disclosed in Table B below [Alk2 being on the right handside]:Table B:Claim 34. Polymer (PA) according to any one of claims 23-33, wherein:- Alki is a linear alkylene group; and / or- Alk2is a linear alkylene group.Claim 35. Polymer (PA) according to any one of claims 23-34, wherein Alki is -CH2-.Claim 36. Polymer (PA) according to any one of claims 22-35, wherein polymer (PA) is a semi-crystalline polymer, notably exhibiting the following thermal properties:- a melting temperature (Tm) of at least 100.0°C; and / or- a heat of fusion (Hm) of at least 25.0 J / g; or the following ones:- a melting temperature (Tm) of at least 130°C; and / or- a heat of fusion (Hm) of at least 30.0 J / g; these properties being measured according to ASTM D3418 or as measured in protocol (p1) of the Experimental Section.Claim 37. Polymer (PA) according to any one of claims 22-36, wherein the melting temperature (Tm) of polymer (PA) is from 40.0 to 200.0°C, more particularly from 40.0°C to 150.0°C, Tm being measured according to ASTM D3418 or as measured in protocol (p1) of the Experimental Section.Claim 38. Polymer (PA) according to any one of claims 22-37, wherein the heat of fusion (Hm) of polymer (PA) is from 10.0 J / g to 50.0 J / g, preferably from 20.0 J / g to 50.0 J / g, more preferably from 25.0 J / g to 50.0 J / g, Hm being measured according to ASTM D3418 or as measured in protocol (p1) of the Experimental Section.Claim 39. Polymer (PA) according to any one of claims 22-38, wherein the glass transition temperature (Tg) of polymer (PA) is t from -40.0 to 100.0°C, more particularly from -30.0°C to 70.0°C, more particularly from -30.0°C to 50.0°C, Tg being measured according to ASTM D3418 or as measured in protocol (p1) of the Experimental Section.Claim 40. Polymer (PA) according to any one of claims 22-39, wherein polymer (PA) is free of lithium, the expression "free of" meaning that the proportion of Li in polymer (PA) is lower than or equal to 500.0 ppm (< 500.0 ppm), preferably lower than or equal to 400.0 ppm (< 400.0 ppm), preferably lower than or equal to 300.0 ppm (< 300.0 ppm), preferably lower than or equal to 200.0 ppm (< 200.0 ppm), preferably lower than or equal to 100.0 ppm (< 100.0 ppm), preferably lower than or equal to 50.0 ppm (< 50.0 ppm), preferably lower than or equal to 10.0 ppm (< 10.0 ppm), preferably lower than or equal to 5.0 ppm (< 5.0 ppm), the proportion of Li in polymer (PA) being notably determined by ICP-OES, notably on a solution obtained after ashing the sample in a furnace and adding nitric acid to the ashes.Claim 41. Polymer (PA) of any one of claims 22-40, exhibiting:- a weight-average molecular weight (Mw) of at least 3,000 g / mol, preferably at least 5,000 g / mol, more preferably at least 10,000 g / mol, more preferably at least 12,000 g / mol, even more preferably at least 20,000 g / mol; and / or- a number-average molecular weight (Mn) of at least 5,000 g / mol, more preferably at least 6,000 g / mol;Mnand Mwbeing determined by Size Exclusion Chromatography (SEC) (polymer in solution in 1 ,1 ,1 ,3,3,3-hexafluoropropan-2-ol with 0.05 mol / L sodium trifluoroacetate; standards used: PMMA).Claim 42. Polymer (PA) of any one of claims 22-41 , exhibiting: a weight-average molecular weight (Mw) between 10,000 and 70,000 g / mol or between 10,000 and 40,000 g / mol; and / or a number-average molecular weight (Mn) between 5,000 and 15,000 g / mol;Mnand Mwbeing determined by Size Exclusion Chromatography (SEC) (polymer in solution in 1 ,1 ,1 ,3,3,3-hexafluoropropan-2-ol with 0.05 mol / L sodium trifluoroacetate; standards used: PMMA).Claim 43. Polymer (PA) according to any one of claims 22-42, exhibiting: a proportion of Li in polymer (PA) lower than or equal to 50.0 ppm; and / or a Mwof at least 3,000 g / mol, preferably at least 5,000 g / mol;the proportion of Li in polymer (PA) being notably determined by ICP-OES, notably on a solution obtained after ashing the sample in a furnace and adding nitric acid to the ashes and Mwbeing determined by Size Exclusion Chromatography (SEC) (polymer in solution in 1 ,1 ,1 ,3,3,3-hexafluoropropan-2-ol with 0.05 mol / L sodium trifluoroacetate; standards used: PMMA).Claim 44. Polymer (PA) according to claim 43, wherein polymer (PA) exhibits a proportion of Li < 10.0 ppm or < 5.0 ppm.Claim 45. Polymer composition (PC) comprising or consisting of:- at least one polymer (PA) as defined in any one of claims 22-44;- optionally at least one polymer additive (Add), notably selected in the group consisting of fillers, colorants, pigments, antioxidants, UV absorbers and combination thereof.Claim 46. Polymer composition (PC) according to claim 45, wherein the proportion of polymer (PA) is at least 30.0 wt%, this proportion being relative to the total weight of composition (PC).Claim 47. A 3D object prepared by the method of claim 2 or any one of claims 3-21 in combination with claim 2 and / or comprising polymer (PA) as defined in any one of claims 22-44.Claim 48. Composition (C) comprising, consisting essentially of or consisting of:- (i) at least one monomer (M) of formula (I):where:• Z designates a -NH-C(=O)- group where NH is linked to either Alki or Alk2;• Alki and Alk2 designate independently a linear or branched C1-C15 alkylene group;- (ii) at least one photoinitiator (P), notably as defined in claim 12 or 13 or 14;- (iii) optionally at least one stabilizer (ST), notably as disclosed herein;- (iv) optionally at least one diluent (S), notably as disclosed herein;- (v) optionally at least one polymer additive (Add), notably selected in the group consisting of fillers, colorants, pigments, antioxidants, UV absorbers and combination thereof.Claim 49. Composition (C) according to claim 48, where monomer (M) is selected in the group of monomers (M1), (M2) and combination (M1) + (M2), where (M1) and (M2) are the following:Claim 50. Composition (C) according to claim 48 or 49, wherein the proportion of monomer(s) (M) in composition (C) is: at least 50.0 wt%; or at least 75.0 wt%; or at least 90.0 wt%; this proportion being relative to the total weight of composition (C).Claim 51. Composition (C) according to any one of claims 48-50, wherein monomer (M) is as defined in any one of the preceding claims, notably in claim 20.Claim 52. Composition (C) according to any one of claims 48-51, wherein monomer (M) isor a combination of these two monomers.Claim 53. Composition (C) according to any one of claims 48-52, wherein photoinitiator (P) is selected from the group consisting of phosphine oxides, benzophenones, thioxanthones, phosphinates, hydroxy ketones and combinations thereof.Claim 54. Composition (C) according to any one of claims 48-53, wherein the proportion of photoinitiator(s) (P) in composition (C) is preferably between 0.1 and 5.0 mol%, this proportion being expressed relative to the total proportion of monomer(s) (M).Claim 55. Use of a composition (C) as defined in any one of claims 48-54 in a photopolymerization process, notably a 3D photopolymerization process, notably such as SLA, DLP, CLIP, PJ or VP.Claim 56. Compound of formulawhere:• Z designates a -NH-C(=O)- group where NH is linked to either Alki or Alk2;• Alki and Alk2 designate independently a linear or branched C1-C15 alkylene group; where Z, Alk1 and Alk2 are notably as defined in any one of the preceding claims.Claim 57. Compound according to claim 56, as defined in Table A below:Table A:where M1 and M2 are as defined in claim 3.Claim 58. Compound according to claim 57, of formula or of formulaClaim 59. Use of a compound as defined in any one of claims 56-58, for the preparation of a polymer by a photopolymerization process, notably a 3D photopolymerization process, notably such as SLA, DLP, CLIP, PJ or VP, the polymer being notably polymer (PA) as disclosed in any one of the preceding claims.

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