Borate ester-based crosslinked polymers with

Abstract

The invention relates to a method for preparing a cross-linked polymer composition containing exchangeable pendant linkers and exchangeable cross-linking groups by a borate metathesis reaction, said method employing a thermoplastic polymer comprising pendant borate groups, and an additive as cross-linking agent, the additive melts in the polymer matrix at a temperature above the processing temperature, referred to as dissociation temperature, thereby cross-linking. The dissociation temperature is achieved only in the subsequent curing step.

Description

Technical Field

[0001] The present invention relates to a process for preparing crosslinked polymers, in particular vitrimers, having improved processability. Background Art

[0002] Like thermosetting polymers, vitrimers have a cross-linked structure that gives them favorable mechanical properties, but they have the ability to flow at high temperatures and can therefore be recycled as thermoplastic polymers.

[0003] In the invention described in applications WO2017 / 029413 and WO2017 / 029412, vitrimers comprising exchangeable boronate linkers have been developed. As fully explained in WO2017 / 029413 and WO2017 / 029412, in particular on pages 2 to 4 of WO2017 / 029413, the metathesis reaction of boronate esters enables exchange reactions between substituents on the boronate ring and can be represented as follows:

[0004]

[0005] Cross-linked polymers, such as vitrimer, can be used to prepare recyclable materials that can be heated to a temperature at which they become liquid without suffering damage or degradation of their structure. However, compared to thermoplastics, the melt viscosity of such cross-linked polymers can decrease slowly with temperature, thus requiring higher temperatures and / or shear forces and / or processing times.

[0006] Therefore, there is a need for a method to improve the processing properties of crosslinked polymers, particularly vitrimer. Summary of the invention

[0007] Surprisingly, the inventors of the present invention have developed a method for preparing crosslinked polymers, wherein the crosslinking is achieved by a post-processing curing step. This method allows the polymer to be processed into a thermoplastic, which is easier to shape, optionally store and transport, and then converted to a crosslinked polymer with exchangeable linking groups, in particular a vitrimer, at a later time when it is suitable for use. The process uses an additive as a crosslinking agent, which melts in the polymer matrix at a temperature above the processing temperature, called the dissociation temperature, thereby crosslinking. The dissociation temperature is only reached in the subsequent curing step.

[0008] The present invention relates to a method for preparing a crosslinked polymer composition containing exchangeable pendant links and exchangeable crosslinks by borate metathesis reaction, the method comprising the following steps:

[0009] (a) Heat the mixture M to temperature T mix , the mixture M comprises:

[0010] - a thermoplastic polymer comprising pendant borate groups independently selected from the group consisting of dioxaborolanes of the following formula EB-1 and dioxaborinanes of the following formula EB-2,

[0011]

[0012] in

[0013] Rx, Rv and Rw are the same or different and each represents a hydrogen atom or a carbon-containing group or form an aliphatic ring or an aromatic ring together in pairs.

[0014] Ry is a carbon-containing group, and Ry is covalently bonded to the boron atom of the dioxaborolane ring or the dioxaborinane ring through the carbon atom;

[0015] o Ry is further linked to the polymer directly via a covalent bond or via a functional group G covalently linked to the polymer; or

[0016] o a substituent selected from Rx, Rw, Rv, {Rx, Rw} or {Rx, Rv} is attached to the polymer via a covalent bond or via a functional group G covalently attached to the polymer,

[0017] - a plurality of molecules of additive A, which are capable of reacting with the pendant borate groups of the thermoplastic polymer to form a crosslinked polymer composition containing pendant linking groups and crosslinking groups exchangeable by borate metathesis reaction, and are capable of forming intermolecular non-covalent interactions with other molecules of additive A and / or with the thermoplastic polymer, such that at temperature T mix In the embodiment of the present invention, the plurality of additive A molecules are associated together and / or with the thermoplastic polymer by non-covalent interactions, and each additive A molecule independently comprises:

[0018] two borate functional groups capable of reacting with pendant borate groups of the thermoplastic polymer, and

[0019] two or more identical or different functional groups F selected from the group consisting of an amide functional group of the formula -NH-C(O)-, a urea functional group of the formula -NH-C(O)-NH- and a carbamate functional group of the formula -OC(O)-NH-,

[0020] Where T mixThe crosslinking agent in the mixture of step (a) has a temperature higher than the glass transition temperature or melting temperature of the thermoplastic polymer used in step (a) and is equal to or lower than the initial dissociation temperature T of the crosslinking agent in the mixture of step (a). dis(i) ,

[0021] (b) recovering a composition comprising the uncrosslinked polymer of step (a) and additive A, and,

[0022] (c) At temperature T c curing the uncrosslinked composition of step (b) to provide a crosslinked polymer composition,

[0023] Where T c Satisfy the following formula:

[0024] T c ≥(T dis(i) +T dis(f) ) / 2, where T dis(i) is the initial dissociation temperature in step (a), T dis(f) is the final dissociation temperature of additive A in the mixture of step (c),

[0025] Initial dissociation temperature T dis(i) is the temperature at which the intermolecular non-covalent interactions formed by multiple molecules of additive A in the mixture of step (A) begin to break,

[0026] and

[0027] Final dissociation temperature T dis(f) It is the temperature at which the intermolecular non-covalent interactions formed by the plurality of additive A molecules in the mixture of step (c) are completely broken.

[0028] According to some embodiments, each additive A molecule comprises two identical borate functional groups.

[0029] According to some embodiments, the plurality of additive A molecules are identical and have formula (IA):

[0030]

[0031] in

[0032] Ar1 is an aromatic group; F1 and F2 are the same or different and are selected from the group consisting of -NH-C(O)-, -C(O)-NH-, -NH-C(O)-NH-, -OC(O)-NH- and -NH-C(O)-O-;

[0033] a, b, i and j are the same or different and are natural integers equal to 0 or 1;

[0034] When a is 1:

[0035] - R2 is C1-C4 alkanediyl or C1-C4 alkenediyl, said alkanediyl or alkenediyl being optionally substituted by one or more halogens, R3 is H, or

[0036] - R2 further forms an aromatic group with R3, provided that i=0, said aromatic group is optionally substituted with one or more halogens;

[0037] When a is 0: the group F1 is directly attached to the carbon atom of the borate ester, and R3 is H;

[0038] When b is 1:

[0039] - R4 is C1-C4 alkanediyl or C1-C4 alkenediyl, the alkanediyl or alkenediyl being optionally substituted by one or more halogens, R5 is H, or

[0040] - R4 further forms an aromatic group with R5, provided that j=0, said aromatic group is optionally substituted by one or more halogens;

[0041] When b is 0: the group F2 is directly attached to the carbon atom of the borate ester, and R5 is H;

[0042] R1 and R6 are the same or different and are each a carbon-containing group.

[0043] According to some embodiments, the plurality of additive A molecules are identical and have formula (IB):

[0044]

[0045] in

[0046] Ar2 and Ar3 are the same or different and are aromatic groups;

[0047] F'1 and F'2 are the same or different and are selected from the group consisting of -NH-C(O)-, -C(O)-NH-, -NH-C(O)-NH-, -OC(O)-NH- and -NH-C(O)-O-;

[0048] a, b, i and j are the same or different and are natural integers equal to 0 or 1;

[0049] When a is 1:

[0050] - R'2 is C1-C4 alkanediyl or C1-C4 alkenediyl, said alkanediyl or alkenediyl being optionally substituted by one or more halogens, R'3 is H, or

[0051] - R'2 further forms an aromatic group with R'3, provided that i=0, said aromatic group is optionally substituted with one or more halogens;

[0052] When a is 0: the group F'1 is directly attached to the carbon atom of the borate ester, and R'3 is H;

[0053] When b is 1:

[0054] - R'4 is C1-C4 alkanediyl or C1-C4 alkenediyl, said alkanediyl or alkenediyl being optionally substituted by one or more halogens, R'5 is H, or

[0055] - R'4 further forms an aromatic group with R'5, provided that j=0, said aromatic group is optionally substituted with one or more halogens;

[0056] When b is 0: the group F'2 is directly attached to the carbon atom of the borate ester, and R'5 is H;

[0057] R7 is a carbon-containing group.

[0058] According to some embodiments, step (b) comprises shaping of the uncrosslinked polymer composition, for example by extrusion, injection, compression, molding or thermoforming.

[0059] According to some embodiments, steps (a) and (b) are achieved simultaneously by extrusion.

[0060] According to some embodiments, step (c) is performed for a period of 1 minute to 1 hour, preferably 2 minutes to 30 minutes, even more preferably 5 minutes to 20 minutes.

[0061] According to some embodiments, the mixture of step (a) comprises 0.05 to 10 wt. %, preferably 0.1 to 3.5 wt. %, more preferably 0.5 to 1.5 wt. % of additive A relative to the weight of the thermoplastic polymer or its blend.

[0062] According to some embodiments, step (c) is performed by compression molding, injection molding and oven curing.

[0063] According to some embodiments, a thermoplastic polymer without any pendant borate groups is further added during step (a).

[0064] According to some embodiments, step (a) comprises the following sub-steps:

[0065] (a1) providing a thermoplastic polymer comprising pendant borate groups as defined in any one of claims 1 to 9, optionally a thermoplastic polymer without any pendant borate groups, or a blend thereof,

[0066] (a2) providing an additive A as defined in any one of claims 1 to 9;

[0067] (a3) At processing temperature T mixThe thermoplastic polymer of step (a1) and the additive A of step (a2) are mixed,

[0068] Where T mix The temperature of the mixture is higher than the glass transition temperature or melting temperature of the thermoplastic polymer provided in step (a1) and is equal to or lower than the initial dissociation temperature T of the crosslinking agent in the mixture of step (a3). dis(i) .

[0069] definition

[0070] The terms "polymer", "linear polymer" and "branched polymer" have the definitions given in WO2017 / 0294123, page 15, line 18 to page 16, line 7, the teaching of which is incorporated herein by reference. According to the present invention, polymers represent linear polymer chains and branched polymer chains.

[0071] "Borate" according to the present invention means a group comprising a dioxaborolane or dioxaborinane moiety.

[0072] The "dioxaborolane moiety" according to the present invention has the following formula:

[0073]

[0074] The "dioxaborinane moiety" according to the present invention has the following formula:

[0075]

[0076] The borate ester group according to the invention is a dioxaborolane or a dioxaborinane:

[0077]

[0078] wherein Ry, Rx, Rw and Rv are as defined below.

[0079] The term "pendant group" as used herein means a side group of a polymer chain, i.e. a substituent that is neither an oligomer nor a polymer. The side group is not integrated into the main chain of the polymer. The term "pendant borate group" as used herein means a borate group (EB1) or (EB2) that is directly attached to a polymer structural unit by a covalent bond or by a functional group G with one and only one of its substituents Ry, Rx, Rw, Rz, {Rx, Rw} or {Rx, Rv}.

[0080] The substituent attached to the polymer chain may be Ry, as defined hereinafter, and the boronate group is then said to be attached to the polymer via the boron atom of the dioxaborolane or dioxaborinane group.

[0081] If they together form an aliphatic or aromatic ring, the substituents attached to the polymer chain may be Rx, Rw, Rv or {Rx, Rw} or {Rx, Rv}, as defined below, and the borate group is said to be attached to the polymer via a carbon atom of the dioxaborolane or dioxaborinane group.

[0082] "Crosslinking" or crosslinking of polymer chains has the definition given in WO2017 / 029413, page 18, line 6 to page 19, line 9, the teaching of which is incorporated herein by reference. It includes the production of covalent chemical bonds between polymer chains that were not initially connected to other chains by covalent bonds. Crosslinking is accompanied by an increase in the connectivity of the various chains that constitute the polymer by covalent bonds. The crosslinking of linear or branched polymer chains is accompanied by an increase in the molecular size of the chain, in particular an increase in the molar mass, and can lead to the acquisition of a network of crosslinked polymers. According to the definition given in WO2017 / 029413, the crosslinking of the crosslinked polymer network is accompanied by an increase in the mass fraction of substances that are insoluble in a non-reactive good solvent.

[0083] The crosslinking of the composition can be evaluated by using dynamic mechanical analysis (DMA). Crosslinking is evaluated by the appearance of a rubbery plateau above the glass transition temperature or melting temperature of the thermoplastic polymer at a frequency of 1 Hz.

[0084] “Glass transition temperature”, T g , defined as the temperature at which the damping factor or loss factor tan δ is maximum by dynamic mechanical analysis at 1 Hz. The damping factor or loss factor tan δ is defined as the ratio of the loss modulus E" to the storage modulus E' (Mechanical Properties of Solid Polymers, Author: I. M. Ward, J. Sweeney; Editor: Wiley-Blackwell; Edition: 3rd Edition; Print ISBN: 9781444319507; DOI: 10.1002 / 9781119967125).

[0085] When a blend of thermoplastic polymers is used in step (a), the relevant glass transition temperature (T g ) or melting temperature (T m ) is the highest T of all thermoplastic polymers present in the blend in a content of at least 8% by weight, in particular at least 4% by weight, especially at least 2% by weight, relative to the total weight of the blend. g or T m It should be understood that it refers to the glass transition temperature (T g ) and the melting temperature when the polymer is semi-crystalline.

[0086] The “initial dissociation temperature” T of the additive A dis(i) is the temperature at which some intermolecular non-covalent bonds formed by a plurality of molecules of additive A with other molecules of additive A or with the thermoplastic polymer in the mixture under consideration begin to break, the mixture may be the mixture of step (a), in particular the mixture of step (a3), the composition of step (b) or the composition of step (c). In other words, the aggregation of the plurality of molecules of additive A with other molecules of additive A or with the thermoplastic polymer at temperature T dis(i) Dissociation begins.

[0087] T dis(i) It will therefore depend on the nature of the thermoplastic polymer or polymers provided in step (a) for mixing with additive A and on the amount of said additive A.

[0088] T dis(i) It is preferably determined by VT-FTIR experiment according to the method described in the "Methods" section below. When VT-FTIR experiment is not available, the temperature T dis(i) It can be determined by rheology using a temperature sweep experiment according to the method described in the "Methods" section below.

[0089] The final dissociation temperature of additive A is T dis(f) is the temperature at which all intermolecular non-covalent bonds formed by the plurality of molecules of additive A with other molecules of additive A or with the thermoplastic polymer in the mixture under consideration are completely broken, the mixture being the mixture of step (a), in particular the mixture of step (a3), the composition resulting from step (b), or the composition of step (c). In other words, the aggregation of the plurality of molecules of additive A with other molecules of additive A or with the thermoplastic polymer at temperature T dis(f) Complete dissociation.

[0090] T dis(f) It will therefore depend on the nature of the thermoplastic polymer or polymers provided in step (a) for mixing with additive A and on the amount of said additive A.

[0091] T dis(f) It is usually determined by VT-FTIR experiments according to the method described in the "Methods" section below. When VT-FTIR experiments are not available, the temperature T dis(f) It can be determined by rheology using a temperature sweep experiment according to the method described in the "Methods" section below.

[0092] By definition, for an additive A in a mixture M, the final dissociation temperature T dis(f) Strictly above the initial dissociation temperature T dis(i) .

[0093] According to the present invention, a "carbon-containing group" is a hydrocarbon-based group, which is therefore mainly composed of carbon and hydrogen atoms, which may also include one or more heteroatoms and / or be substituted by one or more halogens. The group preferably includes 1-50, more preferably 1-18, and even more preferably 1-12 carbon atoms.

[0094] According to the present invention, "heteroatom" means sulfur, nitrogen, oxygen, boron, phosphorus or silicon atom. When it replaces a carbon atom, such as methylene, the nitrogen is in the form of -NH- or -N(C1-C6 alkyl)-, and the sulfur is in the form of -S-, -SO- or -SO2-.

[0095] "Halogen" according to the present invention denotes a fluorine, chlorine, bromine or iodine atom.

[0096] The carbon-containing groups may be aliphatic or aromatic.

[0097] "Aliphatic" according to the present invention means an "alkyl", "alkenyl", "alkanediyl", "alkenediyl" or "cycloalkyl" group. The valence of the group will be determined as appropriate.

[0098] In the context of the present invention, an aliphatic group may include heteroatoms. In particular, it may include an ester, amide, ether, thioether, secondary or tertiary amine, carbonate, urethane, urea or anhydride functional group. If applicable, the aliphatic groups may in particular be substituted by halogen, -Rz, -OH, -NH2, -NHRz, -NRzR'z, -C(O)-H, -C(O)-Rz, -C(O)-OH, -C(O)-NRzR'z, -C(O)-O-Rz, -OC(O)-Rz, -OC(O)-O-Rz, -OC(O)-N(H)-Rz, -N(H)-C(O)-O-Rz, -O-Rz, -SH, -S-Rz, -SS-Rz, -C(O)-N(H)-Rz, -N(H)-C(O)-Rz groups, in which Rz, R'z are identical or different and represent C1-C 50 alkyl.

[0099] "Alkyl" according to the present invention means a saturated linear or branched hydrocarbon chain, preferably containing 1 to 50 carbon atoms, more preferably 1 to 18 carbon atoms, and even more preferably 1 to 12 carbon atoms. According to the present invention, ignoring the conventional meaning of the term, "alkyl" may include one or more heteroatoms. Thus, in the context of the present invention, the term "alkyl" also includes "heteroalkyl", i.e. an alkyl group as described above that contains one or more heteroatoms.

[0100] "Alkenyl" according to the present invention means an unsaturated linear or branched hydrocarbon chain, preferably comprising 1 to 50 carbon atoms, more preferably 1 to 18 carbon atoms, still more preferably 1 to 12 carbon atoms. According to the present invention, ignoring the conventional meaning of the term, "alkenyl" may include one or more heteroatoms. Thus, in the context of the present invention, the term "alkenyl" also includes "heteroalkenyl", i.e. an alkenyl as described above that comprises one or more heteroatoms.

[0101] "Alkanediyl" according to the present invention means a divalent saturated linear or branched hydrocarbon chain, preferably comprising 1 to 50 carbon atoms, more preferably 1 to 18 carbon atoms, still more preferably 1 to 12 carbon atoms. According to the present invention, ignoring the strict meaning of the term, "alkanediyl" may also include one or more heteroatoms. Thus, in the context of the present invention, the term "alkanediyl" also includes "heteroalkanediyl", i.e. an alkanediyl as described above comprising one or more heteroatoms.

[0102] "Alkenediyl" according to the present invention means a divalent unsaturated linear or branched hydrocarbon chain, preferably containing 1 to 50 carbon atoms, more preferably 1 to 18 carbon atoms, still more preferably 1 to 12 carbon atoms, such as vinylene (ethylene) or propenylene. According to the present invention, ignoring the strict meaning of the term, "alkenediyl" may also include one or more heteroatoms. Thus, in the context of the present invention, the term "alkenediyl" also includes "heteroalkenediyl", i.e., alkenediyl as described above containing one or more heteroatoms.

[0103] "Cycloalkyl" according to the present invention means a cyclic alkyl chain which may be saturated or partially unsaturated but not aromatic, preferably containing 3-10 carbon atoms in the ring. The cyclic alkyl chain may include one or more heteroatoms; in this case it will be specifically referred to as "heterocycloalkyl". The group may include more than one ring and so include fused, linked or spiro rings. Examples include cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, pyrrolidinyl, piperidinyl, piperazinyl or morpholinyl. If applicable, the cycloalkyl radicals may in particular be substituted by halogen, -Rz, -OH, -NH2, -NHRz, -NRzR'z, -C(O)-H, -C(O)-Rz, -C(O)-OH, -C(O)-NRzR'z, -C(O)-O-Rz, -OC(O)-Rz, -OC(O)-O-Rz, -OC(O)-N(H)-Rz, -N(H)-C(O)-O-Rz, -O-Rz, -SH, -S-Rz, -SS-Rz, -C(O)-N(H)-Rz, -N(H)-C(O)-Rz radicals, wherein Rz, R'z are identical or different and represent C1-C 50 Alkyl. A cycloalkyl group may, if applicable, be divalent; in this case it is preferably referred to as a "cycloaliphatic" group.

[0104] "Aromatic" according to the present invention means a monovalent or polyvalent group containing an aromatic hydrocarbon group. The valence of the group will be determined on a case-by-case basis.

[0105] The aromatic group may include heteroatoms; in this case it is referred to as a "heteroaromatic" group. In particular, it may include ester, amide, ether, thioether, secondary or tertiary amine, carbonate, urethane, urea or anhydride functional groups. The aromatic group may include one or more fused or covalently linked rings. If applicable, the aromatic groups may be substituted in particular by halogen, Rz, OH, NH2, NHRz, NRzR'z, -C(O)-H, -C(O)-Rz, -C(O)-OH, -C(O)-NRzR'z, C(O)-O-Rz, -OC(O)-Rz, -OC(O)-O-Rz, -OC(O)-N(H)-Rz, -N(H)-C(O)-O-Rz, -O-Rz, -SH, -S-Rz, -SS-Rz, -C(O)-N(H)-Rz, -N(H)-C(O)-Rz groups, in which Rz, R'z are identical or different and represent C1-C 50 An alkyl group may be substituted with a functional group selected from polymerizable functional groups.

[0106] The term "aromatic" includes "aromatic aromatic" groups, i.e. groups comprising at least one aromatic group and at least one aliphatic group as defined. The aliphatic group may be attached to one part of the molecule and the aromatic group to another part of the molecule. The group may include two aromatic groups, each attached to one part of the molecule and connected by an aliphatic chain.

[0107] According to the invention, "aromatic" means an aromatic hydrocarbon group. The term "aromatic" includes aromatic alkyl and alkyl-aromatic groups. The aromatic hydrocarbon group may be substituted one or more times by halogen, -Rz, -OH, -NH2, -NHRz, -NRzR'z, -C(O)-H, -C(O)-Rz, -C(O)-OH, -C(O)-NRzR'z, -C(O)-O-Rz, -OC(O)-Rz, -OC(O)-O-Rz, -OC(O)-N(H)-Rz, -N(H)-C(O)-O-Rz, -O-Rz, -SH, -S-Rz, -SS-Rz, -C(O)-N(H)-Rz, -N(H)-C(O)-Rz groups, wherein Rz, R'z are identical or different and represent C1-C 50 alkyl.

[0108] "Alkyl-aryl" according to the invention denotes an alkyl group as defined above which is linked to the rest of the molecule via an aromatic group as defined above.

[0109] "Arylalkyl" according to the invention denotes an aryl group as defined above which is linked to the rest of the molecule via an aliphatic group as defined above.

[0110] "Heteroaromatic" according to the invention means an aromatic group in which at least one of the atoms of the aromatic ring is a heteroatom. "Heteroalkyl-aryl" according to the invention means an alkyl-aryl group as defined substituted by at least one heteroatom. "Heteroaralkyl" according to the invention means an aralkyl group as defined substituted by at least one heteroatom. BRIEF DESCRIPTION OF THE DRAWINGS

[0111] Figure 1 A. VT-FTIR heating of 1 wt% P / 1 mixture as defined in the Examples, 3 min isotherms per 5 °C, α is 3292 cm -1 Normalized intensity of the hydrogen bond NH stretching band at .

[0112] Figure 1 B. Rheological temperature sweep experiment at 1 rad / s: 1 wt% of the P / 1 mixture, as defined in the examples, was heated at a rate of 10°C / min.

[0113] Figure 1 C. DSC of the first heat of neat 1, as defined in the Examples.

[0114] Figure 1 D. DSC of the first heating of 1 wt% P / 1 mixture, as defined in the examples. Both DSC experiments were performed at a ramp rate of 10°C / min.

[0115] Figure 2 A. Force required to keep the screw speed rotating constant as a function of extrusion time for mixtures of 1 and 2 with P as defined in the examples (solid and dashed lines, respectively). Both extrusions were carried out at 100°C.

[0116] Figure 2 B. Normalized stress relaxation (normalized relaxation modulus as a function of time) at 100°C after extrusion of polymer P with 1 wt% of 1 and 2 at 100°C (solid and dashed lines, respectively), as defined in the Examples, and after extrusion and compression molding of polymer P with 1 wt% of 1 at 220°C for 10 minutes (dashed line).

[0117] Figure 3DMA of the material obtained after extrusion of polymer P with 1 wt% of 1 (i.e. after steps (a) and (b)), as defined in the examples (black solid line), of the material obtained after extrusion of polymer P with 1 wt% of 1 and compression molding (at 220°C for 10 minutes, black dashed line) (i.e. after steps (a), (b) and (c)) and of the recovered material (light grey dashed line). The frequency is 1 Hz. DETAILED DESCRIPTION

[0118] The method of the present invention comprises the following steps:

[0119] (a) Heat the mixture M to temperature T mix , the mixture M comprises:

[0120] - a thermoplastic polymer as defined herein, and

[0121] - an additive A as defined herein,

[0122] Where T mix is higher than the glass transition temperature or melting temperature of the thermoplastic polymer used in step (a), and

[0123] T mix is equal to or lower than the initial dissociation temperature T of the additive A in the mixture of step (a) dis(i) ,

[0124] (b) recovering a composition comprising the uncrosslinked polymer of step (a) and additive A, and

[0125] (c) At temperature T c curing the non-crosslinked composition of step (b) to provide a crosslinked polymer composition,

[0126] Where T c Satisfy the following formula:

[0127] T c ≥(T dis(i) +T dis(f) ) / 2, where T dis(i) is the initial dissociation temperature of additive A in the mixture of step (a), T dis(f) is the final dissociation temperature of additive A in the composition of step (c).

[0128] Thermoplastic polymers

[0129] The thermoplastic polymer used in step (a) comprises pendant borate ester groups independently selected from the group consisting of dioxaborolanes of the following formula EB-1 and dioxaborinanes of the following formula EB-2:

[0130]

[0131] in

[0132] Rx, Rv and Rw are the same or different and each represents a hydrogen atom or a carbon-containing group or together form an aliphatic ring or an aromatic ring in pairs, and

[0133] Ry is a carbon-containing group, and Ry is covalently bonded to the boron atom of the dioxaborolane ring or the dioxaborinane ring through the carbon atom.

[0134] When Rx and Rv together form an aliphatic or aromatic ring, the corresponding group is referred to as {Rx, Rv}. The same applies to the group formed by Rx and Rw.

[0135] Each pendant boronate group is linked to the polymer via one or more carbon atoms of the dioxaborolane or dioxaborinane ring, i.e. via Rx, Rw and / or Rv (if applicable), or via a boron atom of the dioxaborolane or dioxaborinane ring, i.e. via Ry. Accordingly:

[0136] - Ry is further linked to the polymer directly via a covalent bond or via a functional group G covalently linked to the polymer; or

[0137] - A substituent selected from Rx, Rw, Rv, {Rx, Rw} or {Rx, Rv} is linked to the polymer via a covalent bond or via a functional group G covalently linked to the polymer.

[0138] Preferably, Rx, Rw and Rv are identical or different, and represent alkyl, alkenyl, aryl, aralkyl, alkyl-aryl or cycloalkyl separately.Described alkyl, alkenyl, aryl, aralkyl, alkyl-aryl or cycloalkyl can contain the heteroatom that is particularly selected from O, N, S or Si, and / or can be substituted.Described alkyl, alkenyl, aryl, aralkyl, alkyl-aryl or cycloalkyl one or more, preferably one to four methylene units are optionally replaced by-O-,-S-,-C (O)-,-SO2-,-NH- or-N (C1-C6 alkyl)-.Especially, Rx and / or Rw and / or Rv form aliphatic ring or aromatic ring together in pairs.

[0139] In particular, these radicals Rx, Rw and Rv may be substituted by functional groups selected in particular from the group consisting of halogen, -Rz, -OH, -NH2, -NHRz, -NRzR'z, -C(O)-H, -C(O)-Rz, -C(O)-OH, -C(O)-NRzR'z, -C(O)-O-Rz, -OC(O)-Rz, -OC(O)-O-Rz, -OC(O)-N(H)-Rz, -N(H)-C(O)-O-Rz, -O-Rz, -SH, -S-Rz, -SS-Rz, -C(O)-N(H)-Rz, -N(H)-C(O)-Rz radicals, wherein Rz, R'z are identical or different and represent C1-C 50 alkyl.

[0140] In particular, these groups Rx, Rw and Rv may include ester, amide, carbamate, ether, thioether, secondary or tertiary amine, carbonate, urethane, urea (ie a urea function of the formula -NH-C(O)-NH-) or anhydride functions.

[0141] Preferably, Ry represents alkyl, alkenyl, aryl, aralkyl, alkyl-aryl or cycloalkyl. The alkyl, alkenyl, aryl, aralkyl, alkyl-aryl or cycloalkyl may contain heteroatoms particularly selected from O, N, S or Si, and / or may be substituted. One or more, preferably one to four methylene units in the alkyl, alkenyl, aryl, aralkyl, alkyl-aryl or cycloalkyl are optionally substituted by-O-,-S-,-C(O)-,-SO2-,-NH- or-N(C1-C6 alkyl)-. In particular, this group Ry may be substituted by a functional group selected in particular from the group consisting of halogen, -Rz, -OH, -NH2, -NHRz, -NRzR'z, -C(O)-H, -C(O)-Rz, -C(O)-OH, -C(O)-NRzR'z, -C(O)-O-Rz, -OC(O)-Rz, -OC(O)-O-Rz, -OC(O)-N(H)-Rz, -N(H)-C(O)-O-Rz, -O-Rz, -SH, -S-Rz, -SS-Rz, -C(O)-N(H)-Rz, -N(H)-C(O)-Rz, wherein Rz, R'z are identical or different and represent a C1-C 50 In particular, this group Ry may include an ester, an amide, a carbamate, an ether, a thioether, a secondary or tertiary amine, a carbonate, a urethane, a urea (ie a urea functional group of the formula -NH-C(O)-NH-) or an anhydride functional group.

[0142] Each pendant borate group is preferably linked to the polymer chain or to a functional group G covalently attached to the polymer via Rx and / or Ry, as defined below. When their substituents {Rx, Rw} or {Rx, Rv} together form an aliphatic ring or an aromatic ring, the pendant borate group may be linked to the polymer chain or to a functional group G covalently attached to the polymer chain via its substituents {Rx, Rw} or {Rx, Rv} and / or Ry, as defined below.

[0143] The one or more pendant boronate groups may in particular be selected from the boronate groups described in Example 1 of WO 2017 / 029413, the contents of which are incorporated herein by reference.

[0144] According to some embodiments, EB-1 and EB-2 are selected from the group consisting of:

[0145]

[0146] The wavy line indicates the connection point with the functional group G, and the functional group G is directly connected to the polymer through a covalent bond.

[0147] As a non-limiting example, the functional group G can be the result of the reaction of a thiol functional group with an olefinic bond of a polydiene, such as polybutadiene, polyisoprene and copolymers thereof, vinyl copolymers with pendant olefin groups, or polyolefins obtained by ring-opening metathesis polymerization (ROMP) or acyclic diene metathesis (ADMET) (Charles E. Hoyle, Christopher N. Bowman, Angew. Chem. Int. Ed. 2010, 49, 1540-1573; Kemal Arda Günay, Patrick Theato, Harm-Anton Klok, Journal of Polymer Science Part A: Polymer Chemistry 2013, 51, 1-28). The functional group G may also be the result of free radical grafting of maleimide or methacrylic acid, acrylic acid, styrene or maleate functional groups onto, for example, polyethylene and polypropylene (G. Moad, Prog. Polym. Sci. 1999, 24, 81-142; Elisa Passagliaa, Serena Coiai, Sylvain Augier, Prog. Polym. Sci. 2009, 34, 911-947). The functional group G can be the result of the reaction of an isocyanate functional group on the polymer with a pendant alcohol, amine or thiol group (Kemal Arda Günay, Patrick Theato, Harm-Anton Klok, Journal of Polymer Science Part A: Polymer Chemistry 2013, 51, 1-28; Charles E. Hoyle, Andrew B. Lowe, Christopher N. Bowman, Chem. Soc. Rev., 2010, 39, 1355-1387). The functional group G can also be the result of Michael addition of an electrophilic olefin group with a nucleophilic reagent such as a thiol, a primary or secondary amine or a phosphine (Brian D. Mather, Kalpana Viswanathan, Kevin M. Miller, Timothy E. Long, Prog. Polym. Sci. 2006, 31, 487-531). Among the electrophilic olefin groups, non-limiting examples include acrylates, acrylamides, maleimides, methacrylates, and vinyl sulfones.The functional group G can also be the result of a nucleophilic substitution or ring-opening reaction with a nucleophilic functional group such as an alcohol, thiol, amine or carboxylic acid (Kemal Arda Günay, Patrick Theato, Harm Anton Klok, Journal of Polymer Science Part a: Polymer Chemistry 2013, 51, 1-28). For example, these nucleophilic functional groups can open epoxides present in the polymer backbone, as found in epoxidized natural rubber, or open pendant epoxide functional groups, as found in vinyl copolymers prepared with glycidyl methacrylate. The functional group G can also be an ester, thioester or amide functional group produced by the reaction of an alcohol, thiol or amine functional group with a pendant ester or activated ester functional group. The method is particularly useful for vinyl polymers functionalized with pendant ester functional groups, such as polymethyl methacrylate. The functional groups that enable the covalent attachment of the molecule containing the borate functional group to the polymer are therefore diverse, and a person skilled in the art knows how to select the functional group of choice depending on the functional groups present on the polymer and the grafting conditions (temperature, reaction medium (molten or in solution), kinetics, use of catalysts, etc.).

[0148] According to some embodiments, the thermoplastic polymer comprising two or more pendant borate groups used in step (a) is as defined in WO2017 / 029413 for thermoplastic polymers carrying borate functional groups P1, in particular on page 26, line 10 to page 30, line 2 and page 37, line 30 to page 38, line 17, the contents of which are incorporated herein by reference.

[0149] The thermoplastic polymer and additive A are prepared under the processing conditions described below by, for example, WO2017 / 029413, page 28, line 27 to page 29, line 9, page 30, line 4 to page 32, line 33, page 39, line 19 to page 40, line 19 and Figure 2 The borate metathesis reaction described herein is incorporated herein by reference to react together to form crosslinks. In particular, the molar ratio of [repeat units of polymers without pendant borate functional groups] / [repeat units of polymers with pendant borate functional groups] is preferably 0.01-1000, more preferably 0.1-250, and even more preferably 1-100. The crosslinking groups obtained can be exchanged by borate metathesis reactions. The inventors believe that exchange reactions between borate esters enable crosslinking connections to be cyclic and can explain the thermoplastic behavior when the composition itself is insoluble like a thermosetting material.

[0150] The thermoplastic polymer may contain additional side groups which do not contain borate groups. In particular, these side groups may contain functional groups capable of forming non-covalent bonds, such as aromatic groups, in particular phenyl groups, halogen groups,

[0151] The amide functional group of the formula -NH-C(O)-, the urea functional group of the formula -NH-(O)-NH- and the carbamate functional group of the formula -OC(O)-NH.

[0152] Halogen atoms can form dipole-dipole interactions. Aromatic rings can achieve π-π stacking.

[0153] In some embodiments, a blend of thermoplastic polymers comprising pendant borate groups as defined above is used in step (a).

[0154] In some embodiments, a blend of a thermoplastic polymer comprising pendant borate groups as described above and a thermoplastic not comprising pendant borate groups as defined above is used in step (a).

[0155] Additive A

[0156] Additive A is a molecule capable of reacting with the pendant borate groups of the thermoplastic polymer to form a crosslinked polymer composition, preferably a crosslinked network, containing pendant linking groups and crosslinking groups exchangeable by borate metathesis reaction and capable of forming intermolecular non-covalent interactions with other molecules of additive A and / or with the thermoplastic polymer. To this end, each molecule of additive A comprises:

[0157] two boronate functional groups. Each boronate functional group comprises a dioxaborolane moiety or a dioxaborinane moiety. The two boronate functional groups are linked to the rest of the molecule via at least one carbon atom of the dioxaborolane ring or the dioxaborinane ring or via a boron atom of the dioxaborolane or the dioxaborinane ring, and

[0158] Two or more identical or different functional groups F selected from the group consisting of an amide functional group of the formula -NH-C(O)-, a urea functional group of the formula -NH-C(O)-NH- and a carbamate functional group of the formula -OC(O)-NH-.

[0159] The molecules of additive A may also contain other functional groups capable of forming non-covalent interactions between molecules, such as halogen atoms capable of forming dipole-dipole interactions, aliphatic groups capable of performing van der Waals interactions, and aromatic rings capable of achieving π-π stacking. Preferably, the molecules of additive A further contain aromatic rings,

[0160] Particularly optionally substituted phenyl.

[0161] Preferably, the molecule of additive A comprises two or more, in particular two identical, functional groups F, selected from the group consisting of an amide functional group of formula -NH-C(O)-, a urea functional group of formula -NH-C(O)-NH- and a carbamate functional group of formula -OC(O)-NH-.

[0162] The molecules of additive A are preferably identical to one another.

[0163] Depending on the temperature, the molecules of additive A are able to "associate", which means to form intermolecular non-covalent interactions with other molecules of additive A and / or with the thermoplastic polymer.

[0164] As the temperature increases, the molecules will subsequently dissociate from other molecules of additive A and / or the thermoplastic polymer. In the context of the present invention, additive A and the thermoplastic polymer of step (a) are selected so that the initial dissociation temperature T of the molecules of additive A is dis(i) Above the glass transition temperature (T g ) or melting temperature (T m ).

[0165] Examples of intermolecular non-covalent bonds include hydrogen bonding, particularly hydrogen bonding formed by urea, amide and / or carbamate functional groups, π-π stacking in the presence of aromatic groups, van der Waals interactions, dipole-dipole interactions and coordination bonds.

[0166] Thus, the plurality of additive A molecules are capable of forming intermolecular non-covalent interactions with other molecules of additive A and / or with the thermoplastic polymer through the presence of at least two or more identical or different functional groups F, wherein the functional groups F are selected from the group consisting of an amide functional group of the formula -NH-C(O)-, a urea functional group of the formula -NH-C(O)-NH- and a carbamate functional group of the formula -OC(O)-NH-.

[0167] At a temperature lower than or equal to the initial dissociation temperature T dis(i) At a temperature of 1000 ℃ and above, the formation of such intermolecular non-covalent interactions prevents crosslinking between the molecules of additive A and the thermoplastic polymer. In fact, when such intermolecular non-covalent interactions are formed, the molecules of additive A are in a spatial orientation and arrangement such that one or more borate functional groups cannot react with the pendant borate groups of the thermoplastic polymer to achieve crosslinking.

[0168] Since step (a) is carried out at a temperature T mix Less than or equal to T dis(i) , in T mixThe additive A molecules are associated together and / or with the thermoplastic polymer via non-covalent interactions.

[0169] Preferably, each additive A molecule independently comprises a group Y between two borate functional groups, Y being defined as the core of the molecule. Preferably, the core of the additive A molecule has a symmetry element selected from a mirror plane or a C2 rotation axis. Preferably, the molecule, and not just its core Y, has a symmetry element selected from a mirror plane or a C2 rotation axis.

[0170] Preferably, the molecule of additive A has formula (IA) or (IB).

[0171] According to one embodiment, the molecule of additive A has formula (IA):

[0172]

[0173] in

[0174] Ar1 is an aromatic group,

[0175] F'1 and F'2 are the same or different and are selected from the group consisting of -NH-C(O)-, -C(O)-NH-, -NH-C(O)-NH-, -OC(O)-NH- and -NH-C(O)-O-;

[0176] a, b, i and j are the same or different and are natural integers equal to 0 or 1;

[0177] When a is 1:

[0178] - R2 is C1-C4 alkanediyl or C1-C4 alkenediyl, said alkanediyl or alkenediyl being optionally substituted by one or more halogens, R3 is H, or

[0179] - R2 further forms an aromatic group with R3, provided that i=0, said aromatic group is optionally substituted by one or more halogens;

[0180] When a is 0: F1 is directly connected to the carbon atom of the borate ester, and R3 is H;

[0181] When b is 1:

[0182] - R4 is C1-C4 alkanediyl or C1-C4 alkenediyl, the alkanediyl or alkenediyl being optionally substituted by one or more halogens, R5 is H, or

[0183] - R4 further forms an aromatic group with R5, provided that j=0, said aromatic group is optionally substituted by one or more halogens;

[0184] When b is 0: F2 is directly attached to the carbon atom of the borate ester, and R5 is H;

[0185] R1 and R6 are the same or different and are each a carbon-containing group, preferably substituted by one or more halogens.

[0186] Preferably, the substituents finally present on the groups Ar1, R1 to R6 do not contain a functional group selected from the group consisting of -NH-C(O)-, -C(O)-NH-, -NH-C(O)-NH-, -OC(O)-NH- and -NH-C(O)-O-. Thus, only F1 and F2 can be amide functional groups, urea functional groups, carbamate functional groups.

[0187] Advantageously, Ar1 has a symmetry element selected from the mirror plane or the C2 rotation axis. Ar1 is preferably an aromatic or heteroaromatic group in its divalent form. More preferably, Ar1 is an unsubstituted phenylene. More preferably, Ar1 is an unsubstituted phenylene and the borate functional group is para-positioned; thus the molecule corresponds to the following formula:

[0188]

[0189] In all implementations:

[0190] Preferably, i=j.

[0191] Preferably, F1 and F2 are identical and are selected from amide functional groups, carbamate functional groups and urea functional groups.

[0192] Preferably, a=b.

[0193] R2 is preferably -CH2- or -CH2-CH2-, or, provided that i=0, R2 can form a phenylene group with R3 and then with the borate ester to form a group corresponding to the following formula:

[0194]

[0195] R4 is preferably -CH2- or -CH2-CH2-, or, provided that j = 0, R4 can form a phenylene group with R5 and then form a group corresponding to the following formula with a boric acid ester:

[0196]

[0197] Preferably, R2 and R4 are the same.

[0198] R1 and R6 can be independently selected from a wide range of carbon-containing groups. R1 and R6 are identical or different and preferably represent alkyl, alkenyl, aryl, cycloalkyl, heteroaryl, heteroalkyl or heterocycloalkyl, and each of these groups can be substituted, in particular by one or more halogen atoms. Preferably, R1 and R6 are themselves crystalline, so that the melting point of their corresponding molecules is preferably above 0°C. R1 and R6 are identical or different and preferably represent cyclohexyl, alkyl containing 1 to 6 carbon atoms or phenyl.

[0199] In particular, Ar1, F1, F2, i, j, R3, R5, a, b, R2 and R4 are selected such that the molecule has a symmetry element selected from the mirror plane or the C2 rotation axis.

[0200] According to some embodiments, the molecules of additive A are selected from the group consisting of:

[0201]

[0202]

[0203] According to another embodiment, the molecule of additive A has formula (IB):

[0204]

[0205] in

[0206] Ar2 and Ar3 are the same or different and are aromatic groups;

[0207] F'1 and F'2 are the same or different and are selected from the group consisting of -NH-C(O)-, -C(O)-NH-, -NH-C(O)-NH-, -OC(O)-NH- and -NH-C(O)-O-;

[0208] a, b, i and j are the same or different and are natural integers equal to 0 or 1;

[0209] When a is 1:

[0210] - R'2 is C1-C4 alkanediyl or C1-C4 alkenediyl, said alkanediyl or alkenediyl being optionally substituted by one or more halogens, R'3 is H, or

[0211] - R'2 further forms an aromatic group with R'3, provided that i=0, said aromatic group is optionally substituted with one or more halogens;

[0212] When a is 0: F'1 is directly attached to the carbon atom of the borate ester, and R'3 is H;

[0213] When b is 1:

[0214] - R'4 is C1-C4 alkanediyl or C1-C4 alkenediyl, said alkanediyl or alkenediyl being optionally substituted by one or more halogens, R'5 is H, or

[0215] - R'4 further forms an aromatic group with R'5, provided that j=0, said aromatic group is optionally substituted with one or more halogens;

[0216] When b is 0: F'2 is directly attached to the carbon atom of the borate ester, and R'5 is H;

[0217] R7 is a carbon-containing group.

[0218] Preferably, the substituents finally present on the groups Ar2, Ar3, R'2 to R'5 and R7 do not contain a functional group selected from the group consisting of -NH-C(O)-, -C(O)-NH-, -NH-C(O)-NH-, -OC(O)-NH- and -NH-C(O)-O-. Thus, only F'1 and F'2 can be amide functional groups, urea functional groups, carbamate functional groups.

[0219] R7 can be widely selected from carbon-containing groups. R7 preferably represents an alkyl, alkenyl, aromatic, cycloalkyl, heteroaromatic, heteroalkyl or heterocycloalkyl group in its divalent form, and each of these divalent groups can be substituted, in particular by one or more halogen atoms. R7 preferably represents a phenylene group. More preferably, R7 is an unsubstituted phenylene group, and F'1 and F'2 are in para position; thus the molecule corresponds to the following formula:

[0220]

[0221] Preferably, F'1 and F'2 are both amide functional groups or carbamate functional groups or urea functional groups.

[0222] Advantageously, F'1-R7-F'2 has a symmetry element chosen from a mirror plane or a C2 rotation axis.

[0223] In all implementations:

[0224] Preferably, i=j.

[0225] Preferably, a=b.

[0226] R'2 is preferably -CH2- or -CH2-CH2-, or, provided that i = 0, R'2 can form a phenylene group with R'3 and then form a group corresponding to the following formula with a boric acid ester:

[0227]

[0228] R'4 is preferably -CH2- or -CH2-CH2-, or, provided that j = 0, R'4 can form a phenylene group with R'5 and then form a group corresponding to the following formula with a boric acid ester:

[0229]

[0230] Preferably, R'2 and R'4 are the same.

[0231] Ar2 and Ar3 are the same or different and are aromatic or heteroaromatic. Preferably, Ar2 and Ar3 are crystalline themselves, so the melting point of their corresponding molecules is preferably above 0°C. More preferably, Ar2 is unsubstituted phenylene. More preferably, Ar2 is unsubstituted phenylene.

[0232] In particular, Ar2, Ar3, F'1, F'2, i, j, R'2 to R'5, a, b and R7 are selected such that the molecule has a symmetry element selected from the mirror plane or the C2 rotation axis.

[0233] According to some embodiments, the molecules of additive A are selected from the group consisting of:

[0234]

[0235] Use of a compound of formula (IA) or a compound of formula (IB) results in a crosslinked polymer / vitrimer containing pendant linking groups and crosslinking groups exchangeable via borate metathesis reactions, which will depend on the nature of the atom through which the pendant borate functional group is attached to the thermoplastic polymer.

[0236] Thus, when the pendant borate group of formula EB-1 or EB-2 is attached to the thermoplastic polymer via at least one carbon atom of the dioxaborolane ring or dioxaborinane ring (i.e., via Rx, Rw and / or, if applicable, via Rv), the compound of formula (IA) is selected as the molecule of additive A.

[0237] Thus, when the pendant boronate group of formula EB-1 or EB-2 is attached to the thermoplastic polymer via the boron atom of the dioxaborolane or dioxaborinane ring (ie, via Ry), the compound of formula (IB) is selected as the molecule of additive A.

[0238] Preferred embodiments of the method of the present invention

[0239] Step (a)

[0240] Preferably, the mixture of step (a) comprises from 0.05 to 10 wt. %, preferably from 0.1 to 3.5 wt. %, more preferably from 0.5 to 1.5 wt. % of additive A relative to the weight of the thermoplastic polymer or its blend.

[0241] Advantageously, step (a) comprises the following consecutive sub-steps:

[0242] (a1) providing a thermoplastic polymer comprising pendant borate groups as defined herein,

[0243] (a2) providing an additive A as defined herein,

[0244] (a3) At processing temperature T mix The thermoplastic polymer of step (a1) and the additive A of step (a2) are mixed,

[0245] Where T mix The temperature is higher than the glass transition temperature or melting temperature of the thermoplastic polymer provided in step (a1) and is equal to or lower than the initial dissociation temperature T of the additive A in the mixture of step (a3). dis(i) .

[0246] Advantageously, step (a3) ​​is performed for a period of 30 seconds to 2 hours, preferably 1 minute to 1 hour, even more preferably 2 minutes to 30 minutes. It should be understood that the duration of step (a3) ​​is set so that the thermoplastic polymer does not degrade during step (a3).

[0247] Processing temperature T mix The glass transition temperature T of the thermoplastic polymer preferably contained in the mixture with the additive A g Or melting temperature T m The initial dissociation temperature T of the additive A in the mixture of step (a) dis(i) between T g +5℃, or T m +5℃ to T dis(i) -5°C, or even more preferably between T g +10℃ or T m +10℃ to T dis(i) -10℃.

[0248] At the end of step (a), a non-crosslinked polymer composition is provided, which comprises a mixture of the thermoplastic polymer or its blend and the additive A. In other words, the non-crosslinked composition comprises a thermoplastic polymer containing pendant borate groups, or a blend thereof, or a blend thereof with a thermoplastic containing no pendant borate groups, with the additive A mixed therewith. dis(i)At a temperature of 100°C, the molecules of additive A in the non-crosslinked polymer composition form non-covalent interactions with other molecules of additive A and / or with the thermoplastic polymer, blocking the exchange reaction by metathesis between the borate substituents of the polymer and the borate substituents of additive A.

[0249] Step (b)

[0250] In step (b), the non-crosslinked polymer composition is recycled. During the recycling process, the composition is generally formed by processes known to those skilled in the art, including compression molding, injection molding, extrusion, blow molding, fiber spinning, powder coating, rotational molding and thermoforming.

[0251] Steps (a) and (b) can be achieved simultaneously by performing extrusion. Accordingly, the mixing of step (a) is carried out in an extruder.

[0252] Step (b) may also include adding additives to the uncrosslinked composition, such as pigments, colorants, bluing agents, fillers, plasticizers, resistance modifiers, fibers, flame retardants, antioxidants, lubricants, wood, glass and metals.

[0253] The uncrosslinked polymer recovered in step (b) can be stored, transported, used in appropriate applications, pelletized, dispersed in a resin, and the like.

[0254] All operations performed in step (b) are performed at or below the initial dissociation temperature T of the additive A in the uncrosslinked polymer composition. dis(i) carried out at a temperature of .

[0255] Step (c)

[0256] During the curing step, the non-crosslinked polymer composition recovered in step (b) is heated to a temperature T c The non-covalent bonds between the molecules of the additive A in the non-crosslinked polymer composition are completely broken, that is, the aggregated molecules of the additive A are dissociated, and the additive A and the borate functional groups of the polymer are crosslinked to produce a crosslinked polymer composition, especially a vitrimer composition. In this step, the additive A acts as a crosslinking agent.

[0257] At temperature T c Cross-linking can occur. c Satisfy the following formula:

[0258] T c ≥( Tdis(i) +T dis(f) ) / 2, where T dis(i) is the initial dissociation temperature in the mixture of step (a), T dis(f)is the final dissociation temperature of additive A in the composition of step (c).

[0259] It should be understood that T c The temperature is set below the temperature at which the thermoplastic polymer or blend thereof or additive A starts to degrade, such degradation temperature being known to those skilled in the art.

[0260] Preferably, T c Equal to or higher than T dis(f) Preferably, T c Equal to or lower than T dis(f) +50℃, preferably equal to or lower than T dis(f) +40℃.

[0261] According to a preferred embodiment, step (c) is performed for a period of 1 minute to 1 hour, preferably 2 minutes to 30 minutes, and even more preferably 5 minutes to 20 minutes. It should be understood that the duration of step (c) is set so that the thermoplastic polymer is heated to a temperature of c Does not degrade.

[0262] Step (c) is usually carried out by compression molding, injection molding and oven curing.

[0263] method

[0264] Initial dissociation temperature T of additive A dis( i ) and the final dissociation temperature T dis( f ) Determination of

[0265] By performing a variable temperature Fourier transform infrared spectroscopy (VT-FTIR) experiment on the mixture of step (a)

[0266] This method is the most accurate method.

[0267] The relevant mixture comprising a thermoplastic polymer containing pendant borate ester groups as defined in the present invention and additive A is gradually heated over time by holding the isotherm at 5°C for 3 minutes. By following the stretching bands of the non-covalent bonds formed by the molecules of additive A, e.g. 3292 cm -1 FTIR gives molecular information about the degree of association of the molecules of Additive A by monitoring the hydrogen bond NH stretching bands of the amide functional groups. As the temperature increases, the number of non-covalent bonds monitored decreases until they disappear completely, so the normalized intensity α of the corresponding stretching band also decreases to zero, indicating the dissociation of the molecules of Additive A in the mixture. The operating procedure used to perform this experiment (3-minute isotherm) brings the system closer to equilibrium than the rheological temperature scanning experiment described below, thus providing information about the system on a minute time scale. Therefore, when the normalized intensity of the monitored stretching bands begins to decrease ( Figure 1 The dotted line in A shows that the molecules of additive A begin to dissociate, and the corresponding temperature is the initial dissociation temperature T of additive A. dis(i) The final dissociation temperature of additive A is T dis(f) The temperature corresponding to the disappearance of the stretching band is the temperature at which the normalized intensity α is equal to 0 ( Figure 1 dotted circle in A).

[0268] ·By performing a rheological temperature scanning experiment on the mixture of step (a)

[0269] This less accurate method can be used when VT-FTIR is not available.

[0270] The mixture containing the thermoplastic polymer containing pendant borate groups as defined in the present invention and the additive A is gradually heated over time, usually at 10°C / min. During heating, the shear storage modulus (G') and loss modulus (G") are measured at a frequency of 1 rad / s. As the temperature increases, the shear storage modulus (G') and loss modulus (G") decrease, indicating that the system fluidizes, which is expected to be thermoplastic. From the temperature T( Figure 1 The storage modulus (G'; black solid curve) increases starting from the temperature (dashed line in B). The loss modulus (G"; gray dashed curve) also increases at a temperature slightly above G'. The increase in storage modulus and loss modulus reflects the crosslinking reaction between the thermoplastic polymer and the dissociating additive A. The initial dissociation temperature T dis(i) It is about 30°C-50°C lower than the temperature at which the storage modulus G' starts to increase.

[0271] Example

[0272] Example 1 - Synthesis of Additive 1 (according to the invention)

[0273]

[0274] N-(2,3-Dihydroxypropyl)cyclohexanecarboxamide. 3-Aminopropane-1,2-diol (2.0 g, 22 mmol) and triethylamine (3.26 mL, 0.024 mol) were dissolved in 15 mL DMF and cooled to 0 °C under N2 atmosphere. In a separate flask, cyclohexanecarbonyl chloride (3.22 g, 22 mmol) was dissolved in 10 mL DMF and added dropwise to the solution of 3-aminopropane-1,2-diol and triethylamine. The reaction was maintained at 0 °C for 1 hour and then allowed to warm to room temperature for an additional 18 hours. The reaction mixture was added to 300 mL of brine and extracted with 5×50 mL of 1-butanol. The organic fractions were combined and washed with 150 mL of 0.5 m NaOH (aq), 150 mL of 0.5 m HCl (水溶液)The mixture was washed with 150 mL of brine and then dried over anhydrous MgSO 4 . The solvent was removed under vacuum and the solid was washed with ether to give a white powder (1.72 g, yield = 39%).

[0275] 1 H NMR (400MHz, DMSO-d6, 25℃, TMS) δ7.71(t,J=5.8Hz,1H),4.78(s,1H),4.55(d,J=5.6Hz,1H),3.44(t,J=5.7Hz,1H),3.25(s,2H),3.14(ddd, J=13.4,6.0,5.2Hz,1H),2.96(ddd,J=13.4,6.4,5.5Hz,1H),2.12(ddd,J=11.4,8.1,3.3Hz,1H),1.78–1.52(m,5H),1.41–1.02(m,5H).13C NMR (101MHz, DMSO-d6, 25℃)δ175.76,70.59,63.61,43.89,41.94,29.32,25.49,25.28. 13 Splitting of the cyclohexyl peak was observed in CNMR.

[0276]

[0277] Cross-linker 1. N-(2,3-dihydroxypropyl)cyclohexanecarboxamide (1.76 g, 8.78 mmol), benzene-1,4-diboronic acid (0.728 g, 4.39 mmol), water (5 mL, 0.28 mol) and ethanol (5 mL, 0.109 mol) were added to a round bottom flask with 90 mL of toluene. The flask was connected to a Dean-Stark apparatus and the mixture was heated to reflux. After the wash solution was clarified 3 times (45 ml), the reaction was cooled. The solvent was removed under reduced pressure and the product was crystallized from acetonitrile / DMF after hot filtration to give cross-linker 1 as a white solid (1.49 g, yield = 60%).

[0278] 1H NMR (400MHz, DMSO-d6, 25℃, TMS) δ7.93(t,J=5.9Hz,2H),7.73(s,4H),4.68-4.56(m,2H),4.33(t,J=8.6Hz,2H),4.02 (dd,J=9.1,6.5Hz,2H),3.41-3.19(m,4H),2.12(tt,J=11.3,3.4Hz,2H),1.78-1.50(m,10H),1.41-0.99(m,10H).13C NMR (101MHz, DMSO-d6, 25℃)δ175.89, 133.81, 75.97, 68.23, 43.79, 42.01, 29.09, 25.44, 25.21. No carbon adjacent to boron can be observed. 13 The splitting of the cyclohexyl peak was observed in C NMR. ESI-MS: m / z C 26 H 38 B2N2O6H + Calculated value: 497.2989, measured value: 497.2354.

[0279] Structure of Additive 1:

[0280]

[0281] Example 2: Determining the processing temperature and curing time for a given polymer matrix and additives

[0282] In this example, we used the additive 1 obtained in Example 1 and a polymer P with pendant dioxaborolanes; Mn = 104 kg / mol, 5.7 mol% of repeating units with pendant dioxaborolanes, 86.4 mol% of 2-ethylhexyl methacrylate; 7.9 mol% of styrene; T g =12°C). The polymer P has the following formula:

[0283]

[0284] i)DSC (Differential Scanning Calorimetry);

[0285] First, the melting point of additive A was determined by DSC. Figure 1 C), 1 melts at 262°C with a melting enthalpy of 192 J / g. This temperature is the limit at which the additive can be processed, regardless of the polymer matrix.

[0286] After 1 and P (1 wt % of 1) were blended by extrusion at 100°C for 10 min, the resulting mixture was subjected to DSC ( Figure 1D). Due to the low weight loading, the signal is not very strong, but a melting peak can be identified between 175 and 215 °C, with a peak at 193 °C, which is the reactive melting of 1 in P. It must be noted that the dissociation temperature in the polymer is about 70 °C lower than that of the individual molecules 1, reflecting the interactions that occur between the additive and the polymer matrix (e.g. van der Waals interactions, hydrogen bonds, π-π interactions, covalent coordination bonds).

[0287] ii) VT-FTIR (Variable Temperature Fourier Transform Infrared Spectroscopy);

[0288] VT-FTIR was performed by holding the isotherm at 5 °C for 3 min ( Figure 1 A). FITR is detected by tracking 3292 cm -1 The NH stretching bands of hydrogen bonding at the amide bonds give molecular information about the aggregation degree of additive 1.

[0289] Typically, these bands decrease and disappear when the amount of hydrogen bonding decreases, indicating melting and dissolution of 1 in the polymer matrix. The method used to perform this experiment (3-minute isotherm) allows the system to be closer to equilibrium than the rheological experiments described below, providing information about the system on a minute time scale. Here, melting begins at 100°C with a small fraction of decomposed molecules. The melting process gradually continues until 200°C, at which point hydrogen-bonded amides can no longer be observed. From this, a curing step can be designed, in which the crosslinking temperature T c Should be equal to or higher than (T dis(i) +T dis(f) ) / 2, which is 150°C for this system. Therefore, the curing step is designed to be carried out at 220°C for 10 minutes. Crosslinking should be carried out at a temperature and duration at which the polymer will not degrade. This information is well known to those skilled in the art.

[0290] iii) Rheology

[0291] In order to demonstrate and quantify the crosslinking reaction caused by the melting of 1 in P, a rheological temperature sweep experiment was performed on the mixture of P and 1 at 1 wt % of 1 ( Figure 1B). The samples were heated from 50°C to 250°C at a rate of 10°C / min and the shear storage modulus (G') and loss modulus (G") were measured at a frequency of 1 rad / s. From 50 to 160°C, both moduli decrease with increasing temperature, indicating that the system fluidizes, which is expected to be thermoplastic. Starting from 160°C, the storage modulus (G') increases from 500 Pa to 16000 Pa at 240°C, reaching a plateau. This increase in storage and loss moduli reflects the crosslinking reaction between polymer P and the molten additive 1. The maximum temperature for processing P with 1 without crosslinking can be inferred from rheology and DSC. For this example, crosslinking in rheology starts at 160°C (confirmed by melting at 175°C by DSC (a less sensitive analysis)) when the loading of 1 in P is 1 wt%.

[0292] The processing should preferably be carried out at least 30°C below the temperature at which G' starts to increase during a temperature sweep experiment at a frequency of 1 rad / s and a heating rate of 10°C / min ( Figure 1 B), preferably at least 40°C below the temperature at which G' starts to increase during a temperature scanning experiment carried out at a frequency of 1 rad / s and a heating rate of 10°C / min, and even more preferably at least 60°C below the temperature at which G' starts to increase during a temperature scanning experiment carried out at a frequency of 1 Hz and a heating rate of 10°C / min.

[0293] The above experiments - DSC, rheology, FTIR - allow to define the processing temperature and curing conditions (temperature and duration) for a given additive in a given polymer matrix. In this example, the loading of Additive 1 in P is 1 wt %, and we have to process both components below 100°C or at 100°C. We choose 100°C for 10 minutes; and at or above (T dis(i) +T dis(f) ) / 2T c The curing step was carried out at 220°C (150°C for this system). Therefore, we chose 220°C for 10 minutes.

[0294] Example 3: Process according to the invention using the additive according to the invention or process using a comparative additive We used additive 1 and polymer P as disclosed in Example 2.

[0295] We further use the comparative additive 2 (counterexample) of the following formula:

[0296]

[0297] According to the method of the present invention, at a temperature T of 100°C mixUnder the conditions of 1% by weight, crosslinker 1 was mixed with polymer P and the mixture was extruded at a screw speed of 100 rpm (revolutions per minute). The torque required to keep the screw speed constant was kept constant ( Figure 2 A; solid line). The torque required to rotate the screw is related to the melt viscosity.

[0298] In a counterexample, the same experiment was run using additive 2 instead of 1—at the same molar loading, temperature, and screw speed. The torque increased rapidly and reached a plateau that was more than twice the torque measured when extruding with 1 ( Figure 2 A; dashed line). This clearly shows that under these conditions, the mixture P+2 starts to crosslink during extrusion, whereas no crosslinking occurs during extrusion of the mixture P+1.

[0299] Rheological analysis further showed that the material processed with 2 crosslinked after extrusion (no curing step was required). Figure 2 B) shows the time required for the material to relax stress under constant deformation and gives an indication of the viscosity / fluidity of the material (i.e. the higher the viscosity, the longer the relaxation time). Functional polymer P extruded with 1 wt% of 1 at 100°C completely relaxes stress after about 100 seconds (solid line), resulting in a zero shear viscosity η0 = 120,000 Pa.s and a relaxation time τ = 104 s. When the material obtained by extruding P and 1 at 100°C is cured by compression molding (10 minutes at 220°C), it no longer completely relaxes stress within 10,000 seconds - a residual stress of about 5% after 10,000 seconds - which is common for borate-based vitrimers and constitutes direct evidence of the transformation of the material into a vitrimer (dashed line). The material extruded with 2, without any curing step, does not completely relax stress within 10,000 seconds and shows a residual stress of 14% after 10,000 seconds (dashed line).

[0300] These two experiments show that the mixture polymer P+1 is not crosslinked after extrusion at 100° C., while the mixture polymer P+2 is already crosslinked after extrusion.

[0301] At 100° C., the cured material (polymer P+1 wt.% of 1) was extruded and then compression molded; Figure 2 B, dotted line), combined with the presence of a rubbery plateau in DMA ( Figure 3 , black dashed line) is the characteristic of vitrimer.

[0302] In order to evaluate the recyclability of the vitrimer (cured material) obtained in the examples, the vitrimer was subjected to mechanical testing (tensile testing) to break it and then mechanical recycling. Mechanical recycling was performed by chopping the sample into small pieces and compression molding into the desired shape at 140°C and 1 ton equivalent for 20 minutes. Subsequently, the vitrimer was subjected to mechanical testing (tensile testing) to break it and then mechanical recycling. The mechanical recycling was performed by chopping the sample into small pieces and compression molding into the desired shape at 140°C and 1 ton equivalent for 20 minutes. Figure 3 , grey dashed line) and tensile tests were performed to characterize the obtained recycled materials and compared with vitrimer (Table 1).

[0303] sample Fracture strain (%) Fracture stress (MPa) Young's modulus (MPa) P+1-cured 793±66 0.82±0.05 1.2±0.1 P+1-Recycled 793±99 1.1±0.1 1.8±0.2

[0304] Table 1. Uniaxial tensile tests of the vitrimer obtained by extrusion and compression molding (220°C for 10 minutes, black dashed line) of polymer P at 1 wt% of 1 (P+1-cured) and the recycled vitrimer (P+1-recycled, grey dashed line).

Claims

1. A method for preparing a crosslinked polymer composition containing exchangeable pendant linking groups and exchangeable crosslinking groups by borate metathesis reaction, comprising the following steps: (a) Heat the mixture M to temperature T mix , the mixture M comprises: - a thermoplastic polymer comprising pendant borate groups independently selected from the group consisting of dioxaborolanes of the following formula EB-1 and dioxaborinanes of the following formula EB-2, in Rx, Rv and Rw are the same or different and each represents a hydrogen atom or a carbon-containing group or form an aliphatic ring or an aromatic ring together in pairs. Ry is a carbon-containing group, and Ry is covalently bonded to the boron atom of the dioxaborolane ring or the dioxaborinane ring through the carbon atom; - Ry is further linked to the polymer directly via a covalent bond or via a functional group G covalently linked to the polymer; or - a substituent selected from Rx, Rw, Rv, {Rx, Rw} or {Rx, Rv} is attached to the polymer via a covalent bond or via a functional group G covalently attached to the polymer, - a plurality of molecules of additive A, which are capable of reacting with the pendant borate groups of the thermoplastic polymer to form a crosslinked polymer composition containing pendant linking groups and crosslinking groups exchangeable by borate metathesis reaction, and are capable of forming intermolecular non-covalent interactions with other molecules of additive A and / or with the thermoplastic polymer, such that at temperature T mix In the embodiment of the present invention, the plurality of additive A molecules are associated together and / or with the thermoplastic polymer by non-covalent interactions, and each additive A molecule independently comprises: two borate functional groups capable of reacting with pendant borate groups of the thermoplastic polymer, and two or more identical or different functional groups F, selected from the group consisting of an amide functional group of the formula -NH-C(O)-, a urea functional group of the formula -NH-C(O)-NH- and a carbamate functional group of the formula -OC(O)-NH-, Where T mix The temperature of the crosslinking agent in the mixture of step (a) is higher than the glass transition temperature or melting temperature of the thermoplastic polymer used in step (a) and is equal to or lower than the initial dissociation temperature T of the crosslinking agent in the mixture of step (a). dis(i) , (b) recovering a composition comprising the uncrosslinked polymer of step (a) and additive A, and, (c) At temperature T c curing the uncrosslinked composition of step (b) to provide a crosslinked polymer composition, Where T c Satisfy the following formula: T c ≥(T dis(i) +T dis(f) ) / 2, where T dis(i) is the initial dissociation temperature of step (a), T dis(f) is the final dissociation temperature of additive A in the mixture of step (c), Initial dissociation temperature T dis(i) is the temperature at which the intermolecular non-covalent interactions formed by multiple molecules of additive A in the mixture of step (A) begin to break, and Final dissociation temperature T dis(f) It is the temperature at which the intermolecular non-covalent interactions formed by the plurality of additive A molecules in the mixture of step (c) are completely broken.

2. The method according to claim 1, wherein each molecule of additive A comprises two identical borate functional groups.

3. The method according to claim 1 or 2, wherein the plurality of additive A molecules are identical and have formula (IA): in Ar1 is an aromatic group; F1 and F2 are the same or different and are selected from the group consisting of -NH-C(O)-, -C(O)-NH-, -NH-C(O)-NH-, -OC(O)-NH- and -NH-C(O)-O-; a, b, i and j are the same or different and are natural integers equal to 0 or 1; When a is 1: - R2 is C1-C4 alkanediyl or C1-C4 alkenediyl, said alkanediyl or alkenediyl being optionally substituted by one or more halogens, R3 is H, or - R2 further forms an aromatic group with R3, provided that i=0, said aromatic group is optionally substituted by one or more halogens; When a is 0: the group F1 is directly attached to the carbon atom of the borate ester, and R3 is H; When b is 1: - R4 is C1-C4 alkanediyl or C1-C4 alkenediyl, the alkanediyl or alkenediyl being optionally substituted by one or more halogens, R5 is H, or - R4 further forms an aromatic group with R5, provided that j=0, said aromatic group is optionally substituted by one or more halogens; When b is 0: the group F2 is directly attached to the carbon atom of the borate ester, and R5 is H; R1 and R6 are the same or different and are each a carbon-containing group.

4. The method according to claim 1 or 2, wherein the plurality of additive A molecules are identical and have formula (IB): in Ar2 and Ar3 are the same or different and are aromatic groups; F'1 and F'2 are the same or different and are selected from the group consisting of -NH-C(O)-, -C(O)-NH-, -NH-C(O)-NH-, -OC(O)-NH- and -NH-C(O)-O-; a, b, i and j are the same or different and are natural integers equal to 0 or 1; When a is 1: - R'2 is C1-C4 alkanediyl or C1-C4 alkenediyl, said alkanediyl or alkenediyl being optionally substituted by one or more halogens, R'3 is H, or - R'2 further forms an aromatic group with R'3, provided that i=0, said aromatic group is optionally substituted with one or more halogens; When a is 0: the group F'1 is directly attached to the carbon atom of the borate ester, and R'3 is H; When b is 1: - R'4 is C1-C4 alkanediyl or C1-C4 alkenediyl, said alkanediyl or alkenediyl being optionally substituted by one or more halogens, R'5 is H, or - R'4 further forms an aromatic group with R'5, provided that j=0, said aromatic group is optionally substituted with one or more halogens; When b is 0: the group F'2 is directly attached to the carbon atom of the borate ester, and R'5 is H; R7 is a carbon-containing group.

5. The method according to any one of claims 1 to 4, wherein step (b) comprises shaping of the uncrosslinked polymer composition, for example by extrusion, injection, compression, molding or thermoforming.

6. The method according to any one of claims 1 to 5, wherein steps (a) and (b) are simultaneously achieved by extrusion.

7. The method according to any one of claims 1 to 6, wherein step (c) is performed for a period of 1 minute to 1 hour, preferably 2 minutes to 30 minutes, even more preferably 5 minutes to 20 minutes.

8. The process according to any one of claims 1 to 7, wherein the mixture of step (a) comprises 0.05 to 10 wt. %, preferably 0.1 to 3.5 wt. %, more preferably 0.5 to 1.5 wt. % of additive A relative to the weight of the thermoplastic polymer or its blend.

9. The method according to any one of claims 1 to 8, wherein step (c) is performed by compression molding, injection molding and oven curing.

10. The process according to any one of claims 1 to 9, wherein a thermoplastic polymer without any pendant borate groups is further added during step (a).

11. The method according to any one of claims 1 to 10, wherein step (a) comprises the following sub-steps: (a1) providing a thermoplastic polymer comprising pendant borate groups as defined in any one of claims 1 to 9, optionally a thermoplastic polymer without any pendant borate groups, or a blend thereof, (a2) providing an additive A as defined in any one of claims 1 to 9; (a3) At processing temperature T mix The thermoplastic polymer of step (a1) and the additive A of step (a2) are mixed, Where T mix The temperature of the mixture is higher than the glass transition temperature or melting temperature of the thermoplastic polymer provided in step (a1) and is equal to or lower than the initial dissociation temperature T of the crosslinking agent in the mixture of step (a3). dis(i) .

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