Compositions and methods for creating reversibly crosslinked polymers

Abstract

This invention relates to polymerizable compositions. Polymerizable compositions include -S n - A crosslinking agent comprising a moiety and having at least two polymerizable groups, wherein n is an integer from 1 to 8; one or more monomers having at least one C=C double bond capable of undergoing polymerization; and a polymerization initiator. The present invention further relates to a method for producing a reversibly crosslinked polymer by reacting components of a polymerizable composition, and to the resulting reversibly crosslinkable polymer and its reprocessing / recycling.

Description

Detailed description of the invention

[0001] [Field of Invention] This invention generally relates to the field of creating reversibly crosslinked polymers and reprocessing / recycling such polymers.

[0002] [Background of the Invention] Conventional polymer networks, also known as thermosetting resins, are composed of permanent covalent crosslinks, making reprocessing and recycling of these polymers impractical. Examples of conventional polymer networks produced by high-pressure polymerization include low-density polyethylene (LDPE) and ethylene / VA copolymer (EVA).

[0003] Efforts are being made to incorporate essentially reversible crosslinks into polymer network structures, enabling the reprocessing and recycling of these structures. However, complete recovery of crosslinks after multiple reprocessing steps remains difficult with current technology.

[0004] Therefore, there is a continuous need in this field for the development of novel crosslinking chemistry to obtain reversibly crosslinked polymers that are fully reprocessable and recyclable while maintaining the properties of the original polymer.

[0005] [Overview of the prefecture] In one embodiment, a polymerizable composition is provided herein. The polymerizable composition is -S n - A crosslinking agent comprising a moiety and having at least two polymerizable groups, wherein n is an integer from 2 to 8; one or more monomers having at least one C=C double bond capable of undergoing polymerization; and a polymerization initiator.

[0006] In another embodiment, a method for creating a reversibly crosslinked polymer is provided herein. The method is -S n- The method involves reacting a crosslinking agent, which includes a moiety and has at least two polymerizable groups, where n is an integer from 2 to 8, with one or more monomers having at least one C=C double bond capable of undergoing polymerization, in the presence of a polymerization initiator to produce a reversibly crosslinked polymer. The polymer reversibly dissociates its crosslinking bonds when reprocessed at a temperature above 50°C.

[0007] Another aspect of the present invention relates to a reversibly crosslinkable polymer comprising a reaction product of the polymerizable composition described in the above aspect of the present invention. The reversibly crosslinkable polymer comprises an -SS- moiety.

[0008] Another aspect of the present invention relates to a reversibly crosslinkable polymer obtained according to the method described in the above aspects of the present invention.

[0009] Additional aspects, advantages, and features of the present invention are described herein and, in part, will become apparent to those skilled in the art through the following considerations or may be understood through the practice of the present invention. The invention disclosed herein is not limited to any particular set or combination of aspects, advantages, and features. Various combinations of the described aspects, advantages, and features are considered to constitute the present invention disclosed herein. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 illustrates a reaction scheme for high-pressure polymerization using a dynamic disulfide crosslinking agent (A), and a scheme illustrating an example of a dynamic disulfide crosslinking agent (B) according to the present invention. [Figure 2] Figures 2A and 2B show DSC results for exemplary reversibly crosslinked DSDMA / ethylene copolymers, with DSC chromatography (Figure 2A) and trends in Tc and Tm as crosslinking agent concentration increases (Figure 2B). [Figure 3]Figures 3A and 3B show the storage modulus and loss coefficient (tan delta) results (Figure 3A) of an exemplary reversibly crosslinked DSDMA / ethylene copolymer, and the results of a swelling test of the exemplary copolymer (Figure 3B). [Figure 4] Figure 4 shows the normalized stress relaxation results in an exemplary reversibly crosslinked DSDMA / ethylene copolymer. [Figure 5] Figure 5 illustrates a reworkability test on one of the exemplary samples (A5). [Modes for carrying out the invention]

[0011] [Detailed description of the invention] This disclosure provides polymerizable compositions and methods for creating reversibly crosslinked polymers, the methods using a dynamic crosslinking agent comprising polymerizable groups that enable incorporation into a polymer network structure by polymerization, and reversible bonds that dissociate at high temperatures and recombine upon cooling. This dynamic crosslinking creates a reversible, reworkable, and recyclable polymer network structure.

[0012] <Polymerizable composition> One aspect of the present invention relates to a polymerizable composition. The polymerizable composition is -S n - A crosslinking agent comprising a moiety and having at least two polymerizable groups, wherein n is an integer from 2 to 8; one or more monomers having at least one C=C double bond capable of undergoing polymerization; and a polymerization initiator.

[0013] The crosslinking agent is a dynamic crosslinking agent, meaning that the polymer chains of the polymer formed by polymerization of the crosslinking agent and monomer are covalently bonded via reversible bonds provided by the crosslinking agent. These reversible bonds dissociate at high temperatures and recombine upon cooling. The crosslinking agent further contains polymerizable groups that enable incorporation into the polymer network structure through polymerization.

[0014] The crosslinking agent is -S n- It contains a moiety (where n is an integer from 2 to 8, for example 2 or 3) and has at least two polymerizable groups. The dynamic properties are derived from disulfide bonds or polysulfide bonds. The disulfide bonds or polysulfide bonds dissociate upon heating to form stable thiyl radicals and recombine upon cooling to room temperature to reform the disulfide bonds or polysulfide bonds. The polymerizable groups can include unsaturated bonds capable of undergoing a polymerization reaction to enable the incorporation of a crosslinking agent into the polymer network during the polymerization reaction. For example, the polymerizable groups can include a C=C double bond. The two polymerizable groups may be the same or different.

[0015] Unsaturated bonds capable of undergoing a polymerization reaction (e.g., a C=C double bond) are functional groups including, but not limited to, alkenes, alkynes, nitriles, vinyl groups, acyls, acrylates, (meth)acrylates, styrenes, and vinyl pyridines.

[0016] In some embodiments, the crosslinking agent can be represented by formula (I), (II), (III), (IV), or (V). R 1 R 2 R 3 C-S n -CR 4 R 5 R 6 (I) R 7 -CH(X)-S n -CH(Y)-R 8 (II) R 7 -B1-A1-S n -A2-B2-R 8 (III) R 15 -O-S n -O-R 16 (IV) (R 17 )(R 18 )-P-S n -P-(R 19 )(R 20 ) (V)

[0017] The integer n is between 2 and 8, for example, 2 or 5, 2 to 4, or 2 to 3. Typically, n is 2 or 3. In one embodiment, n is 2. In one embodiment, n is 3.

[0018] R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , R 19 and R 20 Each of these independently consists of a hydrogen atom, a halogen atom, and C 1~20 Linear or branched alkyl, C 2~20 Alkenil, C 2~20 Alkynnyl, nitrile, hydroxyl, ester having 1 to 20 carbon atoms, ether having 1 to 20 carbon atoms, thioether having 1 to 20 carbon atoms, ketone having 1 to 20 carbon atoms, imine, amide, primary amine, secondary amine, tertiary amine, trifluoromethyl, phenyl, benzyl, phenol, pentafluorophenyl, nitroxyl, or silicone having 1 to 20 carbon atoms. 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 , R 18 , R19 and R 20 Each of these can be optionally substituted with one or more alkyl groups, alkenyl groups, hydroxyl groups, or halide groups. Any substituent substitutes a hydrogen atom in these R-variable groups. Exemplary substituents are C1-C6 alkyl groups (linear or branched), C2-C6 alkenyl groups, hydroxyl groups, or halide groups.

[0019] X is CHR 9 R 10 OH, SH, or NHR 11 Y represents CHR 12 R 13 OH, SH, or NHR 14 It represents.

[0020] A1 and A2 are independent of each other, either they do not exist or C1~C 20 Alkylene, C2~C 20 Cycloalkylene, C2~C 20 Divalent form of alkenes, C2~C 20 These are divalent forms of alkynes, arylenes, or combinations thereof, each optionally substituted with one or more alkyl, alkenyl, hydroxyl, or halogen atoms.

[0021] Each of B1 and B2 is either absent, an imine, an amine, a carbonyl, an amide, an ether, or an ester, or a combination thereof.

[0022] The term "divalent form" refers to a divalent radical formed when a hydrogen atom is removed from a functional group, such as alkyl, alkenyl, cycloalkyl, or alkynyl, etc., or when a terminal hydrogen atom is removed from a hydrocarbon, such as alkane, alkene, cycloalkane, or alkyne, etc. For example, in the case of the divalent form (alkenylene) of an alkene, the term refers to a divalent radical from which a hydrogen atom has been removed from each of the two terminal carbon atoms of the alkene chain. The site of the divalent form is defined in the structural formula as a form in which the site is present in the center and both ends of the site are bonded to other parts, bonds, or hydrogen atoms.

[0023] In some embodiments, the crosslinking agent is represented by formula (I). In formula (I), R 1 , R 2 , and R 3 at least one of which contains a C═C double bond, and R 4 , R 5 , and R 6 at least one of which contains a C═C double bond. R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 may be the same or different. (R 1 R 2 R 3 ) and (R 4 R 5 R 6 ) may be the same or different. In some embodiments, each of R 1 and R 4 is H, each of R 2 and R 5 may be H or alkyl, and each of R 3 and R 6 contains a C═C double bond. In some embodiments, each of R 3 and R 6 independently contains alkene, alkyne, nitrile, acyl, acrylate, (meth)acrylate, styrene, or vinylpyridine.

[0024] In some embodiments, the crosslinking agent is represented by formula (II). In formula (II), R 7 and R 8 Each of these contains a C=C double bond. X and Y may be the same or different. 7 and R 8 They may be the same or they may be different. 7 -CH(X)- and CH(Y)-R 8 They may be the same or different. In some embodiments, each of X and Y is independently CHR 9 R 10 OH, SH, or NHR 11 This represents, and here, R 9 , R 10 , and R 11 Each of them is independently H or alkyl. In some embodiments, each of X and Y is independently CHR 9 R 10 or NHR 11 This represents, and here, R 9 , R 10 , and R 11 Each of them is independently H or methyl. In some embodiments, R 7 and R 8 Each of these independently comprises an alkene, alkyne, nitrile, acyl, acrylate, (meth)acrylate, styrene, or vinylpyridine.

[0025] In some embodiments, the crosslinking agent is represented by formula (III). In formula (III), R 7 and R 8 Each of these contains a C=C double bond. A1 and A2 may be the same or different. B1 and B2 may be the same or different. R 7 and R 8 They may be the same or they may be different. 7 -B1-A1- and A2-B2-R 8These may be the same or different. In some embodiments, A1 and A2 are independently absent, or C1-C5 alkylene, C2-C6 cycloalkylene, or phenylene, each optionally substituted with one or more alkyl, hydroxyl, or halogen atoms. In some embodiments, B1 and B2 are independently absent, or divalent forms of amines, amides, or esters. In some embodiments, R 7 and R 8 Each of them is independently a C2-C6 alkenyl, optionally substituted with one or more C1-C3 alkyl groups. In some embodiments, R 7 and R 8 Each of these is independently an unsubstituted C2-C6 alkenyl. In some embodiments, R 7 and R 8 Each of these independently contains a C2-C6 alkynyl, optionally substituted with one or more C1-C3 alkyl or nitrile groups.

[0026] In some embodiments, the crosslinking agent is represented by (III), where n is 2 or 3, and R 7 and R 8 Each of these is independent of C2~C 20 It is an alkenyl, optionally substituted with one or more alkyl or alkenyl groups, and A1 and A2 are independently either absent or C1-C 20 The divalent forms of alkylene or phenyl, each optionally substituted with one or more alkyl, alkenyl, hydroxyl, or halogen atoms, and B1 and B2 are independently either absent or divalent forms of amine, amide, ether, or ester.

[0027] In some embodiments, the crosslinking agent is of the formula: [ka] It has the following structure. The integer n is 2 or 3. In one embodiment, n is 2. In one embodiment, n is 3. The integer t is from 1 to 5, for example, 1 to 4, or 1 to 3. In one embodiment, t is 1. In one embodiment, t is 2. In one embodiment, t is 3. R 7 and R 8 Each of them is independently a C2-C6 alkenyl, optionally substituted with one or more C1-C3 alkyl groups. In some embodiments, R 7 and R 8 Each of these is independently an unsubstituted C2-C6 alkenyl. In some embodiments, R 7 and R 8 Each of them is independently a C2-C4 alkenyl, substituted with one or more methyl groups. Each of B1 and B2 is independently absent, -O-, -OC(O)-, -C(O)O-, -C(O)-, -N(H)-, -N(H)C(O)-, or C(O)N(H)-. In some embodiments, each of B1 and B2 is independently absent, -OC(O)-, -C(O)O-, -N(H)C(O)-, or C(O)N(H)-.

[0028] In some embodiments, the crosslinking agent is of the formula: [ka] It has the following structure. The integer n is 2 or 3. In one embodiment, n is 2. In one embodiment, n is 3. R 7 and R 8 Each of them is independently a C2-C6 alkenyl, optionally substituted with one or more C1-C3 alkyl groups. In some embodiments, R 7 and R 8 Each of these is independently an unsubstituted C2-C6 alkenyl. In some embodiments, R 7 and R 8Each of these is independently a C2-C4 alkenyl, substituted with one or more methyl groups. Each of B1 and B2 is independently absent, -O-, -OC(O)-, -C(O)O-, -C(O)-, -N(H)-, -N(H)C(O)-, or C(O)N(H)-. In some embodiments, each of B1 and B2 is independently -OC(O)-, -C(O)O-, -N(H)C(O)-, or C(O)N(H)-.

[0029] An example of a crosslinking agent is diallyl disulfide. [ka] diallyl trisulfide [ka] Bis(2-methacryloyl)oxyethyl disulfide [ka] diallyl 2,2'-disulfanediyldibenzoate [ka] diallyl 2,2'-disulfane diyl diacetate [ka] diallyl 4,4'-disulfanediyldibutyrate [ka] diallyl 3,3'-disulfanediyldipropionate [ka] Disulfane diirbis(3,1-phenylene) diacrylate [ka] Disulfane diylbis(ethane-2,1-diyl) diacrylate [ka] N,N'-(disulfanediylbis(2,1-phenylene))diacrylamide [ka] N,N'-(disulfanediylbis(4,1-phenylene))diacrylamide [ka] and N,N'-bis(acryloyl)cystamine [ka] That is the case.

[0030] In some embodiments, the crosslinking agent comprises diallyl disulfide. In one embodiment, the crosslinking agent consists of diallyl disulfide.

[0031] In a polymerizable composition for creating a reversibly crosslinked polymer, one or more monomers may include olefin monomers, vinyl monomers, or vinyl ester monomers.

[0032] Suitable olefin monomers may include linear or branched olefins (e.g., α-olefins) having 2 to 12 carbon atoms, 2 to 10 carbon atoms, or 2 to 8 carbon atoms. Exemplary linear or branched olefins include, but are not limited to, ethylene, propylene, 1-butene, 2-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-hexene, 3,5,5-trimethyl-1-hexene, 4,6-dimethyl-1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene. These olefins may contain one or more heteroatoms such as oxygen, nitrogen, or silicon.

[0033] Suitable vinyl monomers are substituted vinyls, for example, R a R b C=CR c R d It can include, where R a and R b Each of these may independently be hydrogen, halogen, alkyl, aryl (e.g., phenyl), arylalkyl (e.g., benzyl), heteroaryl (e.g., pyridinyl), alkenyl, arylalkenyl, hydroxylcarbonyl, alkoxycarbonyl, alkylaminecarbonyl, alkylcarbonyloxy, arylcarbonyloxy, or nitrile. Exemplary vinyl monomers include, but are not limited to, styrene, vinylpyridine, acrylate, methacrylate, acrylonitrile, vinyl ester, vinyl chloride, and isoprene.

[0034] Suitable vinyl ester monomers include aliphatic vinyl esters having 3 to 20 carbon atoms (e.g., 4 to 10 carbon atoms, or 4 to 7 carbon atoms). Exemplary vinyl esters are vinyl acetate, vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versaticate. Aromatic vinyl esters such as vinyl benzoate can also be used as vinyl ester monomers. Common vinyl ester monomers are vinyl acetate, vinyl propionate, vinyl laurate, or vinyl versaticate (e.g., vinyl esters of versatic acid, vinyl neononanoate, or vinyl neodecanoate). Typically, vinyl acetate is used due to its good commercial availability and efficiency in removing impurities during production. Vinyl esters of neononanoic acid (vinyl neononanoate) and vinyl esters of neodecanoic acid (vinyl neodecanoate) are commercially available products obtained from the reaction of acetylene with neononanoic acid and acetylene with neodecanoic acid, respectively, and are commercially available as versatic acid 9 and versatic acid 10.

[0035] When used in polymerizable compositions for creating reversibly crosslinked polymers, monomers may be used alone or in combination of two or more different monomers.

[0036] In some embodiments, one or more monomers in a polymerizable composition for creating a reversibly crosslinked polymer include at least one component selected from the group consisting of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and vinyl acetate.

[0037] In one embodiment, the monomer in a polymerizable composition for creating a reversibly crosslinked polymer is ethylene.

[0038] In one embodiment, ethylene and vinyl acetate are used as monomers in a polymerizable composition for creating a reversibly crosslinked polymer.

[0039] Polymerization initiators may include peroxides (e.g., bifunctional peroxides, peracetic acid compounds, etc.), azo compounds, nitroxides, other -CC-free radical initiators, and mixtures thereof.

[0040] Suitable peroxide compounds used as polymerization initiators include, but are not limited to, cyclic ketone peroxides, bifunctional peroxides, dialkyl peroxides, monoperoxycarbonates, poly(t-butyl)peroxycarbonate polyethers, di-peroxyketals, peresters (e.g., peracetates), and mixtures thereof. In some embodiments, the peroxide compound is a cyclic ketone peroxide, a bifunctional peroxide, a dialkyl peroxide, or a mixture thereof.

[0041] Exemplary peroxide compounds used as polymerization initiators include benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, tert-butylcumyl peroxide, t-butyl-peroxy-2-ethyl-hexanoate, tert-butyl peroxypivalate, tertiary butyl peroxyneodecanoate, t-butyl-peroxy-benzoate, t-butyl-peroxy-2-ethylhexanoate, tert-butyl 3,5,5-trimethylhexanoate peroxide, and tert-butyl peroxypivalate. 2-ethylhexyl carbonate tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butyl peroxide)hexane, 1,1-di(tert-butyl peroxide)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butyl peroxide)hexine-3,3,3,5,7,7-pentamethyl-1,2,4-trioxepane, butyl 4,4-di(tert-butyl peroxide) valerate, di(2,4-dichlorobenzoyl) peroxide, di(4-methylbe) (T-butylperoxyisopropyl)benzene, 2,5-di(cumylperoxy)-2,5-dimethylhexane, 2,5-di(cumylperoxy)-2,5-dimethylhexine, 3,4-methyl-4-(t-butylperoxy)-2-pentanol, 4-methyl-4-(t-amylperoxy)-2-pentanol, 4-methyl-4-(cumylperoxy)-2-pentanol, 4-methyl-4-(t-butylperoxy)-2-pentanone, 4-methyl-4-(t-amylperoxy C)-2-pentanone, 4-methyl-4-(cumylperoxy)-2-pentanone, 2,5-dimethyl-2,5-di-t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-amylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexine-3,2,5-dimethyl-2,5-di(t-amylperoxy)hexine-3,2,5-dimethyl-2-t-butylperoxy-5-hydroperoxyhexane, 2,5-dimethyl-2-cumylperoxy-5-hydroperoxyhexane, 2,5-Dimethyl-2-t-amylperoxy-5-hydroperoxyhexane, m / p-alpha, alpha-di[(t-butylperoxy)isopropyl]benzene, 1,3,5-tris(t-butylperoxyisopropyl)benzene, 1,3,5-tris(t-amylperoxyisopropyl)benzene, 1,3,5-tris(cumylperoxyisopropyl)benzene, di[1,3-dimethyl-3-(t-butylperoxy)butyl]carbonate, di[1,3-dimethyl-3-(t-amylperoxy)butyl]carbonate, di[1,3-dimeth [3-(cumylperoxy)butyl]carbonate, di-t-amylperoxide, t-amylperoxide, t-butylisopropenylcumylperoxide, 2,4,6-tri(butylperoxy)-s-triazine, 1,3,5-tri[1-(t-butylperoxy)-1-methylethyl]benzene, 1,3,5-tri-[(t-butylperoxy)-isopropyl]benzene, 1,3-dimethyl-3-(t-butylperoxy)butanol, 1,3-dimethyl-3-(t-amylperoxy)butanol, di(2-phenoxyethyl)per Oxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, dimyristylperoxydicarbonate, dibenzylperoxydecarbonate, di(isobomyl)peroxydicarbonate, 3-cumylperoxy-1,3-dimethylbutyl methacrylate, 3-t-butylperoxy-1,3-dimethylbutyl methacrylate, 3-t-amylperoxy-1,3-dimethylbutyl methacrylate, tri(1,3-dimethyl-3-t-butylperoxybutyloxy)vinylsilane, 1,3-dimethyl-3-(t-butylperoxy Oxy)butyl N-[1-{3-(1-methylethenyl)-phenyl)1-methylethyl]carbamate, 1,3-dimethyl-3-(t-amylperoxy)butyl N-[1-{3(1-methylethenyl)-phenyl}-1-methylethyl]carbamate, 1,3-dimethyl-3-(cumylperoxy))butyl N-[1-{3-(1-methylethenyl)phenyl}-1-methylethyl]carbamate, 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(t-butylperoxy)cyclohexane, n-butyl 4,4-di(t-amylperoxy)valerate, ethyl 3,3-di(t-butylperoxy)butyrate, 2,2-di(t-amylperoxy)propane, 3,6,6,9,9-pentamethyl-3-ethoxycarbonylmethyl-1,2,4,5-tetraoxacyclononane, n-butyl-4,4-bis(t-butylperoxy)valerate, ethyl-3,3-di(t-amylperoxy)butyrate, benzoyl peroxide, OO-t-butyl-O-hydrogen-monoperoxy-succinate, OO-t-amyl-O-hydrogen-mono Peroxy succinate, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane (or methyl ethyl ketone peroxide cyclic trimer), methyl ethyl ketone peroxide cyclic dimer, 3,3,6,6,9,9-hexamethyl-1,2,4,5-tetraoxacyclononane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperbenzoate, t-butylperoxyacetate, t-butylperoxy-2-ethylhexanoate, t-amylperbene Zoate, t-amyl peroxyacetate, t-butyl peroxyisobutyrate, 3-hydroxy-1,1-dimethyl-t-butyl peroxy-2-ethylhexanoate, OO-t-amyl-O-hydrogen-monoperoxysuccinate, OO-t-butyl-O-hydrogen-monoperoxysuccinate, di-t-butyl diperoxyphthalate, t-butyl peroxy(3,3,5-trimethylhexanoate), 1,4-bis(t-butyl peroxycarbo)cyclohexane, t-butyl peroxy-3,5,5- methylhexanoate, t-butyl-peroxy-(cis-3-carboxy)propionate, allyl 3-methyl-3-t-butylperoxybutyrate, OO-t-butyl-O-isopropyl monoperoxycarbonate, OO-t-butyl-O-(2-ethylhexyl)monoperoxycarbonate, 1,1,1-tris[2-(t-butylperoxy-carbonyloxy)ethoxymethyl]propane, 1,1,1-tris[2-(t-amylperoxy-carbonyloxy)ethoxymethyl]propane; 1,1,-Tris[2-(cumylperoxy-carbonyloxy)ethoxymethyl]propane, OO-t-amyl-O-isopropyl monoperoxycarbonate, di(4-methylbenzoyl)peroxide, di(3-methylbenzoyl)peroxide, di(2-methylbenzoyl)peroxide, didecanoylperoxide, dilauroylperoxide, 2,4-dibromo-benzoylperoxide, succinate peroxide, dibenzoylperoxide, di(2,4-dichloro-benzoyl)peroxide, and combinations thereof.

[0042] Suitable azo compounds used as polymerization initiators include, but are not limited to, azo-peroxide initiators comprising azobisisobutyronitrile (AIBN), 2,2'-azobis(amidinopropyl)dihydrochloride, and mixtures of a peroxide with one or more azodinitrile compounds, such as 2,2'-azobis(2-methylpentanenitrile), 2,2'-azobis(2-methylbutanenitrile), 2,2'-azobis(2-ethylpentanenitrile), 2-[(1-cyano-1-methylpropyl)azo]-2-methylpentanenitrile, 2-[(1-cyano-1-ethylpropyl)azo]-2-methylbutanenitrile, and 2-[(1-cyano-1-methylpropyl)azo]-2-ethylpentanenitrile.

[0043] Suitable nitroxide compounds used as polymerization initiators include 2,2,5,5-tetramethyl-1-pyrrolidinyloxy, 3-carboxy-2,2,5,5-tetramethyl-pyrrolidinyloxy, 2,2,6,6-tetramethyl-1-piperidinyloxy, 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy, 4-methoxy-2,2,6,6-tetramethyl-1-piperidinyloxy, and 4-oxo-2,2,6 ,6-tetramethyl-1-piperidinyloxy, bis-(1-oxy-2,2,6,6-tetramethylpiperidine-4-yl) sebacate, 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl) monophosphonate, N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide, N-tert-butyl-1-dibenzylphosphono-2,2-dimethylpropyl nitroxide, N-te This includes, but is not limited to, rt-butyl-1-di(2,2,2-trifluoroethyl)phosphono-2,2-dimethylpropyl nitroxide, N-tert-butyl-(1-diethylphosphono)-2-methylpropyl nitroxide, N-(1-methylethyl)-1-cyclohexyl-1-(diethylphosphono)nitroxide, N-(1-phenylbenzyl)-(1-diethylphosphono)-1-methylethyl nitroxide, N-phenyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide, N-phenyl-1-diethylphosphono-1-methylethyl nitroxide, N-(1-phenyl2-methylpropyl)-1-diethylphosphono-1-methylethyl nitroxide, N-tert-butyl-1-phenyl-2-methylpropyl nitroxide, N-tert-butyl-1-(2-naphthyl)-2-methylpropyl nitroxide, and combinations thereof.

[0044] Accordingly, one embodiment of the present application relates to a polymerizable composition having a polymerization initiator comprising at least one component selected from the group consisting of azobisisobutyronitrile (AIBN), 2,2'-azobis(amidinopropyl)dihydrochloride, and a peroxide and an azo-peroxide initiator comprising a mixture of one or more azodinitrile compounds selected from the group consisting of 2,2'-azobis(2-methylpentanenitrile), 2,2'-azobis(2-methylbutanenitrile), 2,2'-azobis(2-ethylpentanenitrile), 2-[(1-cyano-1-methylpropyl)azo]-2-methylpentanenitrile, 2-[(1-cyano-1-ethylpropyl)azo]-2-methylbutanenitrile, and 2-[(1-cyano-1-methylpropyl)azo]-2-ethylpentanenitrile. Other embodiments of the present invention relate to a polymerizable composition having a polymerization initiator comprising an azo-peroxide initiator comprising (a) at least one component selected from the group consisting of peroxide, azo compound, peracetate compound, nitroxide, azobisisobutyronitrile (AIBN), and 2,2'-azobis(amidinopropyl)dihydrochloride, or (b) a mixture of a peroxide and one or more azodinitrile compounds selected from the group consisting of 2,2'-azobis(2-methylpentanenitrile), 2,2'-azobis(2-methylbutanenitrile), 2,2'-azobis(2-ethylpentanenitrile), 2-[(1-cyano-1-methylpropyl)azo]-2-methylpentanenitrile, 2-[(1-cyano-1-ethylpropyl)azo]-2-methylbutanenitrile, and 2-[(1-cyano-1-methylpropyl)azo]-2-ethylpentanenitrile.

[0045] In some embodiments, the polymerization initiator comprises at least one component selected from the group consisting of 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 3,4-diethyl-3,4-diphenylhexane, 3,4-dibenzyl-3,4-ditolylhexane, 2,7-dimethyl-4,5-diethyl-4,5-diphenyloctane, and 3,4-dibenzyl-3,4-diphenylhexane.

[0046] <Polymerization and Crosslinking Reactions> Another aspect of the present invention relates to a method for preparing a reversibly crosslinked polymer. The method is -S n - The method involves reacting a crosslinking agent, which includes a moiety and has at least two polymerizable groups, where n is an integer from 2 to 8, with one or more monomers having at least one C=C double bond capable of undergoing polymerization, in the presence of a polymerization initiator to produce a reversibly crosslinked polymer. The polymer reversibly dissociates its crosslinking bonds when reprocessed at a temperature above 50°C.

[0047] All of the above disclosures and embodiments relating to polymerizable compositions for creating reversibly crosslinked polymers, as described above in the embodiments of the present invention relating to polymerizable compositions, comprise a crosslinking agent, one or more monomers, and a polymerization initiator, and are also applicable to this embodiment of the present invention.

[0048] During the reaction step, one or more monomers form a polymer network structure via at least one C=C double bond that allows the monomers to undergo polymerization. Dynamic crosslinkers have at least two polymerizable groups (e.g., C=C double bonds) that allow the crosslinker to be incorporated into the polymer network structure during polymerization. Due to the polymerizable groups contained in the dynamic crosslinker, the dynamic crosslinker can function as other monomers during polymerization, forming copolymers or terpolymers with one or more monomers. For example, polymerizing ethylene monomer using diallyl disulfide as a crosslinker can produce an ethylene / diallyl disulfide copolymer, and polymerizing ethylene monomer and vinyl acetate monomer using diallyl disulfide as a crosslinker can produce an ethylene / vinyl acetate / diallyl disulfide terpolymer. Dynamic crosslinkers further help to link polymer chains formed by one or more monomers, forming a broad crosslink network structure.

[0049] Polymerization reactions can be carried out by various polymerization mechanisms known to those skilled in the art. For example, free radical polymerization is a common polymerization mechanism and is suitable for the reactions described herein. Free radical polymerization is a type of chain growth (chain addition) polymerization that begins by generating free radicals that add monomer units, thus growing polymer chains. Any type of initiation for generating free radicals (free radical initiation) may be suitable for the polymerization reactions described herein. For example, free radicals can be generated by thermal initiation, radiation initiation (e.g., photoinitiation), radiation initiation (e.g., ionizing radiation such as gamma rays and X-rays), or a combination thereof.

[0050] The reactions typically take place under pressures exceeding atmospheric pressure. For example, the pressure for polymerization and / or crosslinking reactions is at least 5 bar, and typically ranges from 5 bar to 5,000 bar, 5 bar to 500 bar, 5 bar to 200 bar, 1,000 bar to 5,000 bar, 1,500 bar to 5,000 bar, 1,000 bar to 3,000 bar, 1,500 bar to 3,000 bar, 1,000 bar to 2,000 bar, or 1,000 bar to 3,000 bar.

[0051] The reaction typically takes place at high temperatures over a wide temperature range. The reaction temperature for polymerization and / or crosslinking reactions is typically at least 30°C and can range from 30°C to 350°C, for example, 150°C to 350°C, 150°C to 280°C, 150°C to 230°C, 150°C to 180°C, 30°C to 280°C, 30°C to 230°C, 30°C to 180°C, or 30°C to 130°C. The appropriate reaction temperature should take into account the polymerization initiator and the dynamic crosslinking agent used. For example, the appropriate reaction temperature should be at least higher than the decomposition temperature of the polymerization initiator. The appropriate reaction temperature should also be below the dissociation temperature of the crosslinking agent, so that the crosslinking bonds (i.e., disulfide bonds or polysulfide bonds) of the crosslinking agent do not dissociate during the reaction.

[0052] The reaction conditions may also include the use of an inert gas (e.g., N2 gas).

[0053] The reaction may be carried out in or without a solvent. The solvent may be used to dissolve the monomer or dynamic crosslinking agent. Suitable solvents include, but are not limited to, deep eutectic solvents, eutectic mixtures, ionic liquids, dimethyl carbonate (green solvent), ethers such as petroleum ether, tetrahydrofuran, or 1,4-dioxane, hydrocarbon solvents such as cyclohexane, heptane, or toluene, esters such as ethyl acetate, ketones (e.g., acetone, or butanone, or cyclohexanone), chlorinated solvents such as dichloromethane, alcohols such as methanol, ethanol, butan-2-ol, butan-1-ol, isopropanol, ethylene glycol, or glycerol, and combinations thereof. In some embodiments, the solvent is water, DMSO, dimethylformamide, butyrolactone, or 1,4-dioxane. In some embodiments, the solvent is an anhydrous liquid. In one embodiment, the solvent is dimethyl carbonate.

[0054] Polymerization and / or crosslinking reactions may be carried out in a batch process as a bulk reaction, or in a continuous process as a continuous reaction, under the reaction temperatures and pressures described above.

[0055] To initiate polymerization and / or crosslinking reactions, the amount of polymerization initiator present in the polymerizable composition is typically 1 × 10¹⁶ wt% of the total amount of the polymerizable composition (including crosslinking agent, monomer, and polymerization initiator). -7The range is from wt% to 5.0wt%, for example, 0.001wt% to 5.0wt%, 0.05wt% to 5.0wt%, 0.01wt% to 5.0wt%, 0.05wt% to 5.0wt%, 0.01wt% to 4.0wt%, 0.05wt% to 4.0wt%, 0.01wt% to 3.0wt%, 0.05wt% to 3.0wt%, 0.01wt% to 2.0wt%, 0.05wt% to 2.0wt%, 0.01wt% to 1.0wt%, 0.05wt% to 1.0wt%, 0.1wt% to 1.0wt%, or 0.1wt% to 0.5wt%.

[0056] Monomers suitable for polymerization and / or crosslinking reactions are those described herein. In some embodiments, one or more monomers for polymerization and / or crosslinking reactions include at least one component selected from the group consisting of ethylene, propylene, 1-butylene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and vinyl acetate.

[0057] In one embodiment, the monomer for polymerization and / or crosslinking is ethylene. The ethylene polymer may be polymerized to form high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), or medium-density polyethylene (MDPE).

[0058] In one embodiment, ethylene and vinyl acetate are used as monomers for polymerization and / or crosslinking reactions. The copolymer formed by polymerization of ethylene and vinyl acetate may be an ethylene-vinyl acetate copolymer (EVA), also known as poly(ethylene-vinyl acetate) (PEVA). The type of copolymer varies depending on the vinyl acetate (VA) content. For example, low-VA (up to about 4%) EVA has properties similar to LDPE but with improved gloss, softness, and flexibility; medium-VA (about 4% to 30%) EVA has the properties of a thermoplastic elastomer material; and high-VA (over 33%) EVA has properties similar to rubber.

[0059] Dynamic crosslinking agents suitable for polymerization and / or crosslinking reactions are those described herein. In some embodiments, the crosslinking agents are diallyl disulfide, diallyl trisulfide, bis(2-methacryloyl)oxyethyl disulfide (DSDMA), ((((disulfandiylbis(4,1-phenylene))bis(azandiyl))bis(carbonyl))bis(azandiyl))bis(ethane-2,1-diyl)bis(2-methyl acrylate) (4MUPD), diallyl 2,2'-disulfandiyldibenzoate, diallyl 2,2'-disulfandiyldiacetate, diallyl 4,4'- The material comprises at least one component selected from the group consisting of disulfandiyldibutyrate, diallyl 3,3'-disulfandiyldipropionate, disulfandiylbis(3,1-phenylene)diacrylate, disulfandiylbis(ethane-2,1-diyl)diacrylate, N,N'-(disulfandiylbis(2,1-phenylene))diacrylamide, N,N'-(disulfandiylbis(4,1-phenylene))diacrylamide, and N,N'-bis(acryloyl)cystamine. In one embodiment, the crosslinking agent comprises diallyl disulfide.

[0060] The dynamic crosslinking agent may be present in the polymerizable composition in various amounts, for example, 0.01 wt% to 50 wt%, 0.05 wt% to 50 wt%, 0.1 wt% to 50 wt%, 0.5 wt% to 50 wt%, 1 wt% to 50 wt%, 5 wt% to 50 wt%, 0.1 wt% to 40 wt%, or 0.5 wt% relative to 100 wt% of the total amount of the polymerizable composition (including the crosslinking agent, monomer, and polymerization initiator). It may be present in amounts ranging from 40 wt%, 1 wt% to 40 wt%, 5 wt% to 40 wt%, 0.1 wt% to 30 wt%, 0.5 wt% to 30 wt%, 0.1 wt% to 20 wt%, 0.5 wt% to 20 wt%, 1 wt% to 20 wt%, 5 wt% to 20 wt%, 0.1 wt% to 10 wt%, 0.5 wt% to 10 wt%, 1 wt% to 10 wt%, or 5 wt% to 10 wt%. Expressed in mol%, the dynamic crosslinking agent may be present in the polymerizable composition at a concentration of at least 0.01 mol%, at least 0.05 mol%, at least 0.1 mol%, at least 0.5 mol%, at least 1 mol%, at least 2 mol%, at least 3 mol%, at least 4 mol%, or at least 5 mol%, relative to 100 mol% of the total amount of the polymerizable composition (including the crosslinking agent, monomer, and polymerization initiator), or at a concentration of 0.01 mol% to 35 mol% (e.g., 0.0%). It may also be present in the following proportions: 5 mol% to 35 mol%, 0.1 mol% to 35 mol%, 0.5 mol% to 35 mol%, 1 mol% to 35 mol%, 5 mol% to 35 mol%, 1 mol% to 30 mol%, 5 mol% to 30 mol%, 1 mol% to 25 mol%, 5 mol% to 25 mol%, 1 mol% to 20 mol%, 5 mol% to 20 mol%, 1 mol% to 15 mol%, 5 mol% to 15 mol%, 1 mol% to 10 mol%, or 5 mol% to 10 mol%).

[0061] <Reversibly crosslinkable polymers and their reprocessing> The method described above yields a reversibly crosslinkable polymer. Therefore, other aspects of the present invention relate to a reversibly crosslinkable polymer obtained according to the method described in the above aspects of the present invention.

[0062] All of the above disclosures and embodiments relating to polymerizable compositions for creating reversibly crosslinked polymers, as described above in the embodiments of the present invention relating to polymerizable compositions, comprise a crosslinking agent, one or more monomers, and a polymerization initiator, and are also applicable to this embodiment of the present invention.

[0063] All of the above disclosures and embodiments of the method for creating reversibly crosslinked polymers, as described above in the embodiment of the present invention, include a variety of suitable reagents, reaction mechanisms, and reaction conditions and are also applicable to this embodiment of the present invention.

[0064] As described above, this method produces a reversibly crosslinkable polymer containing the reaction product of the polymerizable composition described above. In the resulting reversibly crosslinkable polymer, the dynamic crosslinking agent is present in an amount of about 0.01 wt% to about 50 wt% of 100 wt% of the total amount of the reversibly crosslinkable polymer, for example, 0.05 wt% to 50 wt%, 0.1 wt% to 50 wt%, 0.5 wt% to 50 wt%, 1 wt% to 50 wt%, 5 wt% to 50 wt%, 0.1 wt% to 40 wt%, 0.5 wt% to 40 wt%, and 1 wt% It may be incorporated into a reversibly crosslinkable polymer in amounts ranging from 40 wt%, 5 wt% to 40 wt%, 0.1 wt% to 30 wt%, 0.5 wt% to 30 wt%, 0.1 wt% to 20 wt%, 0.5 wt% to 20 wt%, 1 wt% to 20 wt%, 5 wt% to 20 wt%, 0.1 wt% to 10 wt%, 0.5 wt% to 10 wt%, 1 wt% to 10 wt%, or 5 wt% to 10 wt%.

[0065] The polymer network structure obtained in a reversibly crosslinkable polymer is dynamic and contains -SS- bonds that can undergo dissociation and recombination under different conditions (e.g., when the temperature is changed), allowing the polymer to be reprocessed and recycled when the polymer is exposed to stimuli.

[0066] The resulting reversibly crosslinkable polymer may be reprocessed by heating from a temperature (e.g., room temperature) where the dissociation of reversible crosslinks (e.g., -SS- bonds) is inert or substantially inert to a high temperature (e.g., a temperature above 50°C, above 60°C, above 70°C, above 80°C, above 90°C, above 100°C, above 110°C, above 120°C, above 130°C, above 140°C, or above 150°C, depending on the individual crosslinking agent used) where the dissociation of reversible crosslinks (e.g., -SS- bonds) is activated or significantly accelerated. Therefore, a suitable reprocessing / recycling temperature may be at least 50°C, at least 60°C, at least 70°C, at least 80°C, at least 90°C, at least 100°C, at least 110°C, at least 120°C, at least 130°C, at least 140°C, or at least 150°C, depending on the individual crosslinking agent used. In some embodiments, the reprocessing / recycling temperature is in the range of 120°C to 160°C. The polymer can be remolded (e.g., re-formed) at a reprocessing / recycling temperature. The reprocessed / recycled polymer can then be cooled, for example, to room temperature. During cooling, reversible bonds (e.g., -SS- bonds) recombine, thereby rebuilding the polymer network structure. A single reprocessing / recycling step may consist of one round of heating, remolding, and cooling. The heating used to reprocess / recycle a reversibly crosslinkable polymer can be relatively short (e.g., 5 hours, 4 hours, 3 hours, 2 hours, 1 hour, 30 minutes, or less), and furthermore, it provides a reprocessed polymer network structure with fully restored crosslink density (compared to the initial polymer network structure before any reprocessing / recycling).

[0067] Reversibly crosslinkable polymers after a reprocessing / recycling process retain their polymer properties (compared to the properties of the original polymer before any reprocessing / recycling). Therefore, the polymerizable compositions and methods described herein enable the preparation of fully reprocessable / recyclable polymers (compared to conventional polymers created without the use of the dynamic crosslinking agents described herein). [Examples]

[0068] The following examples are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0069] <Example 1 - Exemplary synthesis of reversibly crosslinked polymers> In this example, exemplary reversibly crosslinked polymers were synthesized using ethylene as the monomer and various dynamic disulfides as dynamic crosslinking agents. Dynamic crosslinking agents A to D were used to produce the samples, as shown in Figure 1.

[0070] Polymers were generated in a reaction vessel by free radical polymerization. Since the generated polymers are crosslinkable, differential scanning calorimetry (DSC) was performed on the obtained polymer samples to measure the incorporation of comonomers (dynamic crosslinking agents) into the polymer network structure. It is known that for ethylene-based polymers, increasing the comonomer (and / or dynamic crosslinking agent) content lowers the crystallization temperature (Tc) and melting temperature (Tm).

[0071] DSC was performed under nitrogen conditions in a TA Q2000 instrument. The sample was heated to 300°C at 10°C / min, held at this temperature for 1 minute, cooled to -20°C at 10°C / min, and held at this temperature for 1 minute. Subsequently, the sample was heated to 300°C at 10°C / min. Table 1 shows the crystallization temperature (Tc), melting temperature (Tm, second melting cycle), and endothermic ΔH (J / g, second melting cycle).

[0072] For the swelling test, approximately 0.1 g of polymer sample was placed in 10 mL of toluene or 10 mL of xylene and heated to approximately 100°C for 2 hours. Table 2 shows the observations recorded from the swelling test of the polymer sample.

[0073] [Table 1]

[0074] [Table 2]

[0075] <Example 1a - Exemplary synthesis of reversibly crosslinked polymer (crosslinking agent A)> In this example, ethylene-based polymers incorporating bis(2-methacryloyl)oxyethyl disulfide (DSDMA), a dynamic crosslinking agent A, were prepared by free radical polymerization at various concentrations of the dynamic crosslinking agent. Ethylene (99.95%, Air Liquide, 1200 psi), bis(2-methacryloyl)oxyethyl disulfide (Sigma Aldrich), 2,2'-azobisisobutyronitrile (AIBN, 98%, Sigma Aldrich), and dimethyl carbonate (DMC, 99% anhydrous, Sigma Aldrich) were used in their readily available forms. 100 mL of DMC, 0.1 g of AIBN, and DSDMA (0.25 g, 0.5 g, 1.0 g, or 2.0 g) were added to a Parr reaction vessel.

[0076] The reaction vessel was sealed and purged three times with nitrogen while stirring. After the final nitrogen purge, 50 L of ethylene was added to the system and heated at 90°C for 4 hours. The reaction vessel reached a final pressure in the range of 90–105 bar. The reaction mixture was collected and washed with additional DMC. The polymers were dried overnight in a vacuum oven (samples A1–A5, Tables 1–2).

[0077] Figure 2A shows the DSC chromatography of crosslinking agent A-ethylene polymer, where different concentrations of crosslinking agent A are used (concentrations A1-A5, shown in Tables 1 and 2). As shown in Figure 2B, as the comonomer concentration increases, T m and T cThe expected trend of both decreasing was observed. Figure 3A shows the storage modulus and loss factor (tan delta) of 1 g of DSMDA-ethylene copolymer (sample A3). Dynamic mechanical analysis (DMA) measurements were performed in tensile mode using a TA800DMA instrument. Thin film samples were prepared using a carver press at 175°C with 10 tons of pressure for 1 hour. The samples were cooled to -100°C, and a temperature sweep was performed to 80°C at 3°C / min to measure the viscoelastic response. A preload load of 0.01 N was applied at a frequency of 1 Hz, and the amplitude was set in advance using a strain sweep.

[0078] For the swelling test, approximately 0.1 g of polymer was placed in 10 mL of toluene or 10 mL of xylene. Both samples were heated at approximately 100°C for 2 hours. After 2 hours, the samples did not dissolve and showed the formation of a crosslinked polymer network structure as shown in Figure 3B. DSDMA contains dynamic disulfide bonds, and therefore, polymers containing DSDMA will be dynamic polymers. To investigate the dynamic properties of the polymer, a stress relaxation test (G(t) / G(0)) was performed. The stress relaxation experiment was performed on an ARES G2 rheometer using a parallel plate geometry with a diameter of 25.0 mm and a gap of 1.0 mm. Samples were prepared using a carver press at 175°C for 1 hour and under a pressure of 10 tons. Each sample underwent a strain sweep of 0.1% to 100% to determine the strain within the linear viscoelastic region of the material, and each sample was conditioned at the test temperature for 30 minutes before testing. The test was conducted at a steady-state strain of 1% for 10,000 seconds at a selected temperature.

[0079] Figure 4 shows the normalized stress relaxation of sample A3 at 160°C, 170°C, 180°C, and 190°C. The sample tested at 160°C showed no stress relaxation at all, but all samples tested at 170°C, 180°C, and 190°C showed rapid stress relaxation on longer time scales.

[0080] In addition to stress relaxation, which demonstrates the dynamic properties of these polymers, reworkability tests were conducted. Figure 5 shows the reworkability test of sample A5. The polymer sample obtained from the reaction vessel was molded in a carver press at 160°C for 1 hour at a pressure of 8-10 tons, and then transferred to a cold press (room temperature) and treated at a pressure of 8-10 tons for 5 minutes. The molded sample was homogeneous and there were no visible weld lines (press 1x). The sample molded with press 1x was then cut to a thickness of 3-5 mm and re-pressed under the same conditions (160°C, 1 hour, pressure of 8-10 tons). The molded sample (press 2x) was homogeneous. The same process was repeated to obtain a sample molded with press 3x, and the sample molded with press 3x was also homogeneous. Reworkability indicates the dynamic properties of the polymer network structure.

[0081] <Example 1b - Exemplary synthesis of reversibly crosslinked polymer (crosslinking agent B)> In this example, ethylene-based polymers incorporating diallyl disulfide (DADS), a dynamic crosslinking agent B, were prepared by free radical polymerization at various concentrations of the dynamic crosslinking agent. Ethylene (99.95%, Air Liquide, 1200 psi), diallyl disulfide (≥80% FG, Sigma Aldrich), 2,2'-azobisisobutyronitrile (AIBN, 98%, Sigma Aldrich), and dimethyl carbonate (DMC, 99% anhydrous, Sigma Aldrich) were used in their readily available forms. 100 mL of DMC, 0.1 g of AIBN, and DADS (0.5 mL or 1 mL) were added to a Parr reaction vessel. The reaction vessel was sealed and purged three times with nitrogen while stirring. After the final nitrogen purge, 50 L of ethylene was added to the system and heated at 90°C for 4 hours. The reaction vessel reached a final pressure in the range of 100–105 bar. The reaction mixture was collected and washed with additional DMC. The polymers were dried overnight in a vacuum oven (samples B1 and B2, Tables 1–2).

[0082] <Example 1c - Exemplary synthesis of reversibly crosslinked polymer (crosslinking agent C)> In this example, ethylene-based polymers incorporating the dynamic crosslinking agent C, N,N'-bis(acryloyl)cystamine (BAC), were prepared by free radical polymerization at various concentrations of the dynamic crosslinking agent. Ethylene (99.95%, Air Liquide, 1200 psi), N,N'-bis(acryloyl)cystamine (Sigma Aldrich), 2,2'-azobisisobutyronitrile (AIBN, 98%, Sigma Aldrich), and acetone (99.5% ACS reagent, Sigma Aldrich) were used as available. 100 mL of acetone, 0.1 g of AIBN, and BAC (0.25 g, 1 g, or 2 g) were added to a Parr reaction vessel. The reaction vessel was sealed and purged three times with nitrogen while stirring. After the final nitrogen purge, 50 L of ethylene was added to the system and heated at 90°C for 4 hours. The reaction vessel reached a final pressure in the range of 90–105 bar. The reaction mixture was collected and washed with additional acetone. The polymers were dried overnight in a vacuum oven (samples C1–C3; Tables 1–2).

[0083] <Example 1d - Exemplary synthesis of reversibly crosslinked polymer (crosslinking agent D)> In this example, ethylene-based polymers incorporating the dynamic crosslinking agent D, ((((disulfanediylbis(4,1-phenylene))bis(azandiyl))bis(carbonyl))bis(azandiyl))bis(ethane-2,1-diyl)bis(2-methylacrylate) (4MUPD), were prepared by free radical polymerization at various concentrations of the dynamic crosslinking agent. Ethylene (99.95%, Air Liquide, 1200 psi), 2,2'-azobisisobutyronitrile (AIBN, 98%, Sigma Aldrich), acetone (99.5% ACS reagent, Sigma Aldrich), and tetrahydrofuran (THF, anhydrous 99%, Sigma Aldrich) were used in their readily available forms. 4MUPD was synthesized using the prescribed method. 100 mL of THF or acetone, 0.1 g of AIBN, and 4 MUPD (0.25 g, 0.5 g, 1 g) were added to a Parr reaction vessel. The reaction vessel was sealed and purged three times with nitrogen while stirring. After the final nitrogen purge, 50 L of ethylene was added to the system and heated at 90°C for 4 hours. The reaction vessel reached a final pressure in the range of 90-95 bar. The reaction mixture was collected and washed with additional THF or acetone. The polymers were dried overnight in a vacuum oven. Polymers D1-D3 were polymerized in acetone, and polymers D4 and D5 were polymerized in THF (Tables 1-2).

Claims

1. -S ｎ - A crosslinking agent comprising a part and having at least two polymerizable groups, wherein n is an integer from 1 to 8, One or more monomers having at least one C=C double bond capable of undergoing polymerization, Polymerization initiator and A polymerizable composition containing the following:

2. The crosslinking agent is represented by formula (I), (II), (III), (IV), or (V), R １ R ２ R ３ C-S ｎ -CR ４ R ５ R ６ (I) R ７ -CH(X)-S ｎ -CH(Y)-R ８ (II) R ７ -B １ -A １ -S ｎ -A ２ -B ２ -R ８ (III) R １５ -O-S ｎ -O-R １６ (IV) (R １７ )(R １８ )-P-S ｎ -P-(R １９ )(R ２０ ) (V) During the ceremony, n is an integer from 2 to 8. X is CHR ９ R １０ OH, SH, or NHR １１ This represents, Y is CHR １２ R １３ OH, SH, or NHR １４ This represents, R １ , R ２ , R ３ , R ４ , R ５ , R ６ , R ７ , R ８ , R ９ , R １０ , R １１ , R １２ , R １３ , R １４ , R １５ , R １６ , R １７ , R １８ , R １９ and R ２０ Each of these independently consists of a hydrogen atom, a halogen atom, and C １～２０ Linear or branched alkyl, C ２～２０ Alkenil, C ２～２０ Selected from the group consisting of alkynyl, nitrile, hydroxyl, esters having 1 to 20 carbon atoms, ethers having 1 to 20 carbon atoms, thioethers having 1 to 20 carbon atoms, ketones having 1 to 20 carbon atoms, imines, amides, primary amines, secondary amines, tertiary amines, trifluoromethyl, phenyl, benzyl, phenol, pentafluorophenyl, nitroxyl, and silicones having 1 to 20 carbon atoms, each optionally substituted with one or more alkyl, alkenyl, hydroxyl, or halogen atoms. A １ and A ２ Each of them is independent, does not exist, or C １ ~C ２０ Alkylene, C ２ ~C ２０ Cycloalkylene, C ２ ~C ２０ The divalent form of alkenes, C ２ ~C ２０ These are divalent forms of alkynes, arylenes, or combinations thereof, each optionally substituted with one or more alkyl, alkenyl, hydroxyl, or halogen atoms. B １ and B ２ Each of these independently either does not exist, or is a divalent form of an imine, amine, amide, ether, or ester, or a combination thereof. however, In equation (I), R １ , R ２ , and R ３ At least one of them contains a C=C double bond, R ４ , R ５ , and R ６ At least one of them contains a C=C double bond, and In equations (II) and (III), R ７ and R ８ Each of them contains a C=C double bond, The polymerizable composition according to claim 1.

3. n is either 2 or 3. The polymerizable composition according to claim 2.

4. The C=C double bond capable of undergoing polymerization is a functional group comprising at least one component selected from the group consisting of alkenes, alkynes, nitriles, vinyl groups, acyls, acrylates, (meth)acrylates, styrenes, and vinylpyridines. A polymerizable composition according to claim 1 or claim 2.

5. The aforementioned crosslinking agent is represented by formula (III), where, n is either 2 or 3. R ７ and R ８ Each of them is C ２～２０ It is an alkenyl, and is optionally substituted with one or more alkyl or alkenyl groups. A １ and A ２ Each of them is independent, does not exist, or C １ ~C ２０ It is a divalent form of alkylene or phenyl, each optionally substituted with one or more alkyl, alkenyl, hydroxyl, or halogen atoms, and B １ and B ２ Each of these independently either does not exist or is a divalent form of an amine, amide, ether, or ester. The polymerizable composition according to claim 2.

6. The crosslinking agent comprises at least one component selected from the group consisting of diallyl disulfide, diallyl trisulfide, bis(2-methacryloyl)oxyethyl disulfide, diallyl 2,2'-disulfandiyldibenzoate, diallyl 2,2'-disulfandiyldiacetate, diallyl 4,4'-disulfandiyldibutyrate, diallyl 3,3'-disulfandiyldipropionate, disulfandiylbis(3,1-phenylene) diacrylate, disulfandiylbis(ethane-2,1-diyl) diacrylate, N,N'-(disulfandiylbis(2,1-phenylene)) diacrylamide, N,N'-(disulfandiylbis(4,1-phenylene)) diacrylamide, and N,N'-bis(acryloyl)cystamine. A polymerizable composition according to claim 1 or claim 2.

7. The crosslinking agent comprises at least one of diallyl disulfide, bis(2-methacryloyl)oxyethyl disulfide (DSDMA), and ((((disulfandiylbis(4,1-phenylene))bis(azandiyl))bis(carbonyl))bis(azandiyl))bis(ethane-2,1-diyl)bis(2-methyl acrylate) (4MUPD). The polymerizable composition according to claim 6.

8. The crosslinking agent consists of at least one of diallyl disulfide, bis(2-methacryloyl)oxyethyl disulfide (DSDMA), and ((((disulfandiylbis(4,1-phenylene))bis(azandiyl))bis(carbonyl))bis(azandiyl))bis(ethane-2,1-diyl)bis(2-methyl acrylate) (4MUPD). The polymerizable composition according to claim 7.

9. The one or more monomers mentioned above include olefin monomers or vinyl monomers. A polymerizable composition according to claim 1 or claim 2.

10. The one or more monomers include at least one component selected from the group consisting of ethylene, propylene, 1-butylene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and vinyl acetate. The polymerizable composition according to claim 9.

11. The one or more monomers are ethylene, or ethylene and vinyl acetate. The polymerizable composition according to claim 10.

12. The polymerization initiator comprises at least one component selected from the group consisting of peroxides, azo compounds, peracetic acid compounds, and nitroxides. The polymerizable composition according to claim 1.

13. The polymerization initiator comprises at least one component selected from the group consisting of azobisisobutyronitrile (AIBN), 2,2'-azobis(amidinopropyl)dihydrochloride, and an azoperoxide initiator comprising a mixture of one or more azodinitrile compounds selected from the group consisting of azobis(2-methylpentanenitrile), 2,2'-azobis(2-methylbutanenitrile), 2,2'-azobis(2-ethylpentanenitrile), 2-[(1-cyano-1-methylpropyl)azo]-2-methylpentanenitrile, 2-[(1-cyano-1-ethylpropyl)azo]-2-methylbutanenitrile, and 2-[(1-cyano-1-methylpropyl)azo]-2-ethylpentanenitrile and a peroxide. The polymerizable composition according to claim 1.

14. The polymerization initiator comprises at least one component selected from the group consisting of 2,3-dimethyl-2,3-diphenylbutane, 3,4-dimethyl-3,4-diphenylhexane, 3,4-diethyl-3,4-diphenylhexane, 3,4-dibenzyl-3,4-ditolylhexane, 2,7-dimethyl-4,5-diethyl-4,5-diphenyloctane, and 3,4-dibenzyl-3,4-diphenylhexane. The polymerizable composition according to claim 1.

15. A method for creating a reversibly crosslinked polymer, -S ｎ - A crosslinking agent having at least two polymerizable groups and including a moiety, wherein n is an integer from 1 to 8, and one or more monomers having at least one C=C double bond capable of undergoing polymerization, are reacted in the presence of a polymerization initiator to produce a reversibly crosslinked polymer. A method for reversibly dissociating the crosslinked bonds of the polymer when the polymer is reprocessed at a temperature exceeding 50°C.

16. The reaction step is carried out by free radical initiation, thermal initiation, radiation initiation, irradiation initiation, or a combination thereof. The method according to claim 15.

17. The reaction step described above is carried out under a pressure of at least 5 bar. The method according to claim 15.

18. The reaction step described above is carried out under a pressure of 5 bar to 5000 bar. The method according to claim 17.

19. The reaction step described above is carried out under a pressure of 1,000 to 3,000 bar. The method according to claim 18.

20. The polymerization initiator is present in an amount of 1 × 10¹⁶ per 100% by weight of the total amount of the crosslinking agent, monomer, and polymerization initiator. －７ It is present in amounts ranging from wt% to 5 wt%. The method according to claim 15.

21. The reaction step is carried out as a bulk reaction or a continuous reaction under a pressure of at least 20 bar. The method according to claim 15.

22. The reaction step described above is carried out at a temperature of at least 30°C. The method according to claim 15.

23. The reaction step described above is carried out at a temperature of 30°C to 350°C. The method according to claim 19.

24. The reaction step described above is carried out at a temperature of 150°C to 350°C. The method according to claim 23.

25. The crosslinking agent comprises at least one component selected from the group consisting of diallyl disulfide, diallyl trisulfide, bis(2-methacryloyl)oxyethyl disulfide, diallyl 2,2'-disulfandiyldibenzoate, diallyl 2,2'-disulfandiyldiacetate, diallyl 4,4'-disulfandiyldibutyrate, diallyl 3,3'-disulfandiyldipropionate, disulfandiylbis(3,1-phenylene) diacrylate, disulfandiylbis(ethane-2,1-diyl) diacrylate, N,N'-(disulfandiylbis(2,1-phenylene)) diacrylamide, N,N'-(disulfandiylbis(4,1-phenylene)) diacrylamide, and N,N'-bis(acryloyl)cystamine. The method according to claim 15.

26. The crosslinking agent comprises diallyl disulfide. The method according to claim 25.

27. The aforementioned cross-linking bond is a sulfur-sulfur bond that dissociates at temperatures above 50°C. The method according to claim 15.

28. The one or more monomers include at least one component selected from the group consisting of ethylene, propylene, 1-butylene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and vinyl acetate. The method according to claim 15.

29. The one or more monomers are ethylene, or ethylene and vinyl acetate. The method according to claim 28.

30. A reversibly crosslinkable polymer comprising the reaction product of the polymerizable composition described in claim 1, The aforementioned reversibly crosslinkable polymer is a polymer containing an -S-S- moiety.

31. A reversibly crosslinkable polymer obtained according to the method of claim 15.

32. The crosslinking agent is incorporated into the reversibly crosslinkable polymer in an amount of approximately 0.01 wt% to approximately 50 wt% based on 100% by weight of the total amount of the reversibly crosslinkable polymer. The reversibly crosslinkable polymer according to claim 31.

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