Self-healing polymers

Abstract

This invention relates to self-healing polymer compositions and their use in various fields such as additive manufacturing and robotics. Furthermore, this invention relates to methods for preparing the self-healing polymer and structures containing the polymer.

Description

[Technical Field]

[0001] This invention relates to self-healing polymer compositions and their use in various fields such as additive manufacturing and robotics. Furthermore, this invention relates to methods for preparing the self-healing polymer and structures containing the polymer. [Background technology]

[0002] In the field of robotics, more specifically in the application of soft grippers, it has proven beneficial to use self-healing materials that can repair damage sustained during use to some extent. Soft grippers can be used, for example, for harvesting fruits and vegetables, and they come into close contact with sharp objects (e.g., sharp twigs, thorns, plastic, or glass). As a result, visible damage (e.g., punctures, cuts, and ruptures) occurs over time, negatively impacting the performance of these grippers. Robots are also used in remote applications where repairing or replacing damaged parts is difficult, such as search and recovery in (aero)space or marine environments, or environmental surveys.

[0003] Self-healing materials already exist today, possessing the ability to repair damage without the need to replace the material. Depending on the type of self-healing material, damage can be repaired with or without the application of external stimuli such as heat, pH changes, and light. To obtain self-healing materials, interchangeable dynamic bonds are typically introduced into the polymer network. In response to one or more external stimuli, the dynamic bonds that form crosslinks in the polymer network can be shuffled, thereby allowing the network to change shape and preferably return to its original shape. Ideally, these materials combine the malleability of thermoplastics with the dimensional stability of thermosetting resins, thereby providing a unique combination of physical properties such as improved self-healing and recyclability.

[0004] Polymer networks incorporating dynamic covalent bonds are called covalent compatibility networks (CANs). These covalent compatibility networks can be divided into two subgroups based on how exchange reactions proceed: dissociative mechanisms and associative or degenerate mechanisms. In dissociative exchange, dynamic bonds dissociate before new bonds are formed, while in associative or degenerate exchange, the reaction proceeds via an intermediate state (or transition state) where the entities involved in the exchange are chemically linked. The behavior of covalent compatibility networks depends heavily on these different mechanisms.

[0005] One of the earliest examples of covalent compatibility networks (CANs) following a dissociative mechanism is the Diels-Alder (DA) polymer network, based on a reversible Diels-Alder reaction between functional diene groups and dienophile groups. Therefore, the Diels-Alder bond can be considered a dissociative covalent bond (DCB). A drawback of polymer networks crosslinked by dissociative covalent bonds such as Diels-Alder bonds is the rapid decrease in viscosity upon heating, which can lead to mechanical instability. Other drawbacks include susceptibility to creep or potential vulnerability to certain solvents.

[0006] In contrast to dissociative Diels-Alder networks, vitrimers are polymer networks containing dynamic covalent bonds, i.e., associated covalent bonds (ACBs), that follow an associated or degenerate exchange mechanism. The viscosity change of vitrimers with temperature generally follows Arrhenius's law. Vitrimers typically exhibit good stability and maintain the same crosslinking density, but due to the linear decrease in viscosity with temperature, samples repaired at moderate temperatures are susceptible to significant creep. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Therefore, an object of the present invention is to address the problems associated with self-healing polymers known in the art by providing a novel self-healing polymer composition.

Means for Solving the Problems

[0008] According to a first aspect, the present invention provides a polymer network composition comprising a transesterification catalyst, a polymer network doubly crosslinked by a Diels-Alder reaction product of a maleimide group and a furan group as a dissociative covalent bond (DCB) and an ester group as an associative covalent bond (ACB), wherein the doubly crosslinked polymer network further comprises a hydroxyl group, and the amount of the dissociative covalent bond relative to the total of the dissociative covalent bond and the associative covalent bond (DCB + ACB) crosslinking the network is at least 5%.

[0009] The polymer network composition defined in the first aspect, which has both a Diels-Alder bond as a dissociative covalent bond and an ester bond as an associative covalent bond as crosslinking portions of the polymer network in the presence of a transesterification catalyst, has relaxation dynamics that can be adjusted according to, for example, specific applications, the time frame and / or temperature at which the material is normally used, and / or its processing characteristics.

[0010] During the repair process at high temperature, the dynamic Diels-Alder bonds of the polymer network (representing the DCB of the polymer network) can be reversibly thermally dissociated, the dissociative crosslinks are cleaved, and new crosslinks are formed. At the same time, the ester bonds (representing the ACB of the polymer network) can undergo transesterification with the hydroxyl groups in the polymer network in the presence of a transesterification catalyst, and the associative crosslinks are exchanged between the existing ester bonds and the hydroxyl groups.

[0011] According to one embodiment, the present invention provides a double-crosslinked polymer network composition as defined herein, wherein the amount of dissociative covalent bonds relative to the total of dissociative covalent bonds and associated covalent bonds crosslinking the network is at least 10%, preferably 20% to 99%, more preferably 30% to 95%, even more preferably 40% to 90%, and even more preferably 50% to 80%.

[0012] In a further embodiment, the present invention provides a double-crosslinked polymer network composition as defined herein, wherein at least a portion of the ester groups providing the associated covalent bonds of the double-crosslinked polymer network and at least a portion of the hydroxyl groups contained in the double-crosslinked polymer network are present as β-hydroxyesters.

[0013] According to a further embodiment, the present invention relates to a β-hydroxyester of formula (I): [ka] (In the formula, R1 is -H, -C) 1~18 Alkyl and -C 2~18 Selected from alkenyl, the -C 1~18 Alkyl and the -C 2~18 Each of the alkenyls can be arbitrarily and independently -halo, -OH, and -C. 1~6 Alkyl, -C 1~6 Alkenyl and -OC 1~6 The present invention provides a double-crosslinked polymer network composition as defined herein, which is represented by (substituted with one to three substituents selected from alkyl groups).

[0014] In a further embodiment, the present invention provides a double-crosslinked polymer network composition as defined herein, in which at least a portion of the furan groups of the Diels-Alder bond are connected to the polymer network via a β-hydroxyester linker.

[0015] According to a further embodiment, in the present invention, at least a part of the furan group of the Diels-Alder bond is represented by the formula (II): [Chemical formula] (wherein R1 is selected from -H, -C 1~18 alkyl, and -C 2~18 alkenyl, and each of the -C 1~18 alkyl and the -C 2~18 alkenyl is optionally and independently substituted with one to three substituents selected from -halo, -OH, -C 1~6 alkyl, -C 1~6 alkenyl, and -O-C 1~6 alkyl), Y is selected from -C 1~6 alkylene-, -O-, -C(O)O- and -OC(O)-, X1 and X2 are independently selected from -C 1~6 alkyl-, -C 2~6 [[ID=�3]]alkenyl-, and -C 1~6 alkyl-O-, and each of the -C 1~6 alkyl-, the -C 2~6 alkenyl-, and the -C 1~6 alkyl-O- is optionally and independently substituted with one to three substituents selected from -halo, -OH, -C 1~6 alkyl, -C 1~6 alkenyl, and -O-C 1~6 alkyl), and is connected to the polymer network via a β-hydroxyester linker represented by the above formula), and provides a double-crosslinked polymer network composition defined herein.

[0016] According to a further embodiment, the present invention provides a double-crosslinked polymer network composition defined herein, which further contains a radical scavenger.

[0017] In a further embodiment, the present invention provides a double-crosslinked polymer network composition as defined herein, wherein the transesterification catalyst is selected from zinc acetylacetonate, zinc acetate, dibutyline oxide, tin(II) 2-ethylhexanoate, triazabicyclodecene, 1-methylimidazole, triphenylphosphine, or any combination thereof.

[0018] According to a second aspect, the present invention relates to a method for preparing a polymer network composition as defined herein, comprising a double-crosslinked polymer network, wherein the method is a) A step of preparing a first prepolymer containing a carboxylic acid group, b) A step of functionalizing the first portion of the carboxylic acid group of the first prepolymer with a furan introduction reagent in the presence of a transesterification catalyst, thereby obtaining a furan-functionalized prepolymer containing the second portion of the carboxylic acid group, c) A step of adding a second prepolymer containing an oxirane group or an epoxy group, and a third prepolymer containing a maleimide group to a furan-functionalized prepolymer to obtain a prepolymer mixture, d) A step of stirring the prepolymer mixture at a high temperature to obtain a polymer network composition, Includes, The present invention provides a method in which the first portion is at least 5% of the total amount of carboxylic acid groups of the first prepolymer.

[0019] A method defined in a second embodiment provides a polymer network composition as defined herein, in which a first prepolymer containing carboxylic acid groups is first reacted with a furan introduction reagent in the presence of a transesterification catalyst to functionalize at least 5% (first portion) of the carboxylic acid groups, and then the furan-functionalized prepolymer, still containing the remaining carboxylic acid groups (second portion), is reacted with a second prepolymer containing oxirane or epoxy groups and a third prepolymer containing maleimide groups.

[0020] According to one embodiment, the present invention provides a method, as defined herein, for adding a radical scavenger in any one step before the prepolymer mixture is stirred at a high temperature.

[0021] In a further embodiment, the present invention provides a method as defined herein in which a prepolymer containing a maleimide group has at least two functional values, and in particular the prepolymer containing a maleimide group is bismaleimide.

[0022] In another embodiment, the present invention provides the use of polymer network compositions as defined herein.

[0023] According to one embodiment, the present invention provides the use of a polymer network composition as defined herein as a self-healing material.

[0024] According to further embodiments, the present invention provides the use of polymer network compositions as defined herein in the manufacture of 1D structures, 2D structures, or 3D structures, particularly in the manufacture of robot parts or tires.

[0025] The polymer network compositions defined herein may be particularly suitable for use as self-healing materials in the field of robotics, and more specifically in subfields of soft robotics.

[0026] According to further embodiments, the present invention provides the use of polymer network compositions as defined herein in manufacturing methods selected from the list including filament extrusion, extrusion-based printing techniques, selective laser sintering, injection molding, compression molding, cast molding, and soft lithography.

[0027] According to further embodiments, the present invention provides the use of a polymer network composition as defined herein, wherein the extrusion-based printing technique is selected from a list including a filament dissolution method, a direct ink writing method, and the like.

[0028] According to further embodiments, the present invention provides a 1D structure, a 2D structure, or a 3D structure comprising a polymer network composition as defined herein.

[0029] Referring specifically to the figures here, it should be emphasized that the details shown are illustrative and intended solely for illustrative purposes to illustrate different embodiments of the present invention. They are presented to provide what is considered to be the most useful and straightforward explanation of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for a basic understanding of the present invention. The explanation, together with the drawings, will make it clear to those skilled in the art how some forms of the present invention can actually be embodied. [Brief explanation of the drawing]

[0030] [Figure 1] Figure 1 (also abbreviated as Fig. 1) shows the stress relaxation at different temperatures of polymer network compositions according to embodiments of the present invention, where the relative amount of DA bonds as dissociable covalent bonds differs. Figure 1A shows the relaxation behavior of Comparative Example A (100% DA bonds), Figure 1B shows the relaxation behavior of Comparative Example B (0% DA bonds), and Figure 1C shows the relaxation behavior of Examples 8a to 8e at 140°C. [Figure 2] Figure 2 (also abbreviated as Fig. 2) shows the storage moduli at different temperatures for Examples 8a to 8e and Comparative Examples A and B, which have different relative amounts of DA bonds as dissociable covalent bonds. [Figure 3]Figure 3 (also abbreviated as Fig. 3) shows the creep behavior at different temperatures for Examples 8a to 8e and Comparative Examples A and B, which have different relative amounts of DA bonds as dissociable covalent bonds. [Figure 4] Figure 4, also abbreviated as Fig. 4, is a diagram illustrating the different steps involved in demonstrating the shape memory properties of a sample prepared according to Example 8d. [Modes for carrying out the invention]

[0031] The present invention will be described further below. The following paragraphs will define various aspects of the present invention in more detail. Each of these defined aspects may be combined with any other one or more aspects unless explicitly shown to be contrary. In particular, any feature indicated as preferred or advantageous may be combined with any other one or more features indicated as preferred or advantageous.

[0032] When describing the compounds of the present invention, terms used should be interpreted according to the following definitions unless otherwise indicated by the context.

[0033] The term "alkyl" can refer to the compound C, either by itself or as part of another substituent. x H 2x or C x H 2x+1 This refers to a fully saturated hydrocarbon of the formula (wherein x is a number of 1 or more). Generally, the alkyl groups of the present invention contain 1 to 20 carbon atoms. The alkyl groups may be linear or branched and may be substituted as shown herein. Where a subscript is used after a carbon atom herein, the subscript indicates the number of carbon atoms that the given group may contain. Therefore, for example, C 1~4Alkyl refers to alkyl groups with 1 to 4 carbon atoms. Examples of alkyl groups include methyl, ethyl, n-propyl, i-propyl, butyl, and their isomers (e.g., n-butyl, i-butyl, and t-butyl); pentyl and its isomers, hexyl and its isomers, heptyl and its isomers, octyl and its isomers, nonyl and its isomers; and decyl and its isomers. C1-C6 alkyl groups include all linear, branched, or cyclic alkyl groups containing 1 to 6 carbon atoms, and therefore include methyl, ethyl, n-propyl, i-propyl, butyl, and their isomers (e.g., n-butyl, i-butyl, and t-butyl); pentyl and its isomers, hexyl and its isomers, cyclopentyl, 2-, 3- or 4-methylcyclopentyl, cyclopentylmethylene, and cyclohexyl. An arbitrarily substituted alkyl group refers to an alkyl group having one or more substituents (for example, one, two, three, or four).

[0034] The term "alkenyl" refers to a linear, cyclic, or branched hydrocarbon radical containing at least one carbon-carbon double bond, either by itself or as part of another substituent. Therefore, for example, C 2~4 An alkenyl refers to an alkenyl molecule with 2 to 4 carbon atoms. Examples of alkenyl radicals include ethenyl (vinyl), E- and Z-propenyl, allyl, isopropenyl, E- and Z-butenyl, E- and Z-isobutenyl, E- and Z-pentenyl, E- and Z-hexenyl, E,E-, E,Z-, Z,E-, and Z,Z-hexadienyl. An arbitrarily substituted alkenyl refers to an alkenyl molecule having one or more substituents (for example, one, two, three, or four). A C1 alkenyl refers to the vinyl portion where the C1 substituent, together with the carbon atom to which the substituent is attached, forms a carbon-carbon double bond.

[0035] Where used herein and in the appended claims, the singular forms ("a," "an," and "the") refer to multiple subjects unless the context clearly indicates otherwise. For example, "a compound" means one compound or two or more compounds. The above terms and other terms used herein will be well understood by those skilled in the art. The compounds of the present invention can be prepared according to the reaction schemes presented in the following examples, but those skilled in the art will understand that these are merely illustrative examples of the present invention, and that the compounds of the present invention can be prepared by any of several standard synthesis processes commonly used by those skilled in the art in the field of organic chemistry.

[0036] As described above in this specification, according to a first aspect, the present invention provides a polymer network composition comprising a transesterification catalyst and a polymer network double-crosslinked by a Diels-Alder reaction product of a maleimide group and a furan group as dissociative covalent bonds (DCBs) and an ester group as an associated covalent bond (ACB), wherein the double-crosslinked polymer network further comprises hydroxyl groups, and the amount of dissociative covalent bonds relative to the total of dissociative covalent bonds and associated covalent bonds crosslinking the network is at least 5%.

[0037] A polymer network composition defined in the first embodiment, having both a Diels-Alder reaction product of maleimide and furan groups (DA bonds) as DCBs and an ester group as an ACB as crosslinking portions of the polymer network, has been found to provide tuned relaxation dynamics in the presence of a transesterification catalyst. The material and its relaxation dynamics can be tuned, for example, to specific applications, the time frame and / or temperature in which the material is typically used, and / or its processing characteristics.

[0038] In particular, it was found that polymer networks possessing several dissociative Diels-Alder bonds may offer improved processability in terms of quality and energy efficiency compared to polymer networks possessing only associative bonds. During processing, for example, a network with 0% DA was pressed at 210°C for 1 hour under a pressure of 2t, a network with 30% DA was pressed at 185°C for 1 hour under a pressure of 2t, and a network with 50% DA was pressed at 170°C for 10 minutes under a pressure of 2t to obtain reprocessed polymer networks.

[0039] As described herein, the dynamic Diels-Alder bonds (representing DCBs in the polymer network) can be reversibly thermally dissociated during the high-temperature repair process, cleaving the dissociative crosslinks and forming new crosslinks. Simultaneously, the ester bonds (representing ACBs in the polymer network) can undergo transesterification with hydroxyl groups in the polymer network during the high-temperature repair process in the presence of a transesterification catalyst, exchanging associated crosslinks between existing ester bonds and hydroxyl groups. The presence of hydroxyl groups in the double-crosslinked polymer network enables the transesterification of ester crosslinks.

[0040] Figure 1 shows that a polymer network composed solely of DCB, i.e., Diels-Alder bonds (100% DA), relaxes external stresses several orders of magnitude faster at a given temperature than a polymer network composed solely of associated covalent bonds (0% DA).

[0041] Figure 2 shows that the behavior of materials with different relative amounts of DA bonds as dissociative covalent bonds in terms of mechanical properties is very similar around room temperature, but changes by several orders of magnitude at high temperatures. Here again, tools are provided to adjust the behavior of materials.

[0042] Furthermore, crosslinked polymer compositions as defined herein may have improved self-healing dynamics and / or be less susceptible to creep compared to polymer networks having only associated bonds or only dissociative bonds. Crosslinked polymer compositions as defined herein may have a more linear decrease in viscosity with temperature and / or be less susceptible to creep and / or degradation due to exposure to solvents compared to polymer networks having only dissociative bonds.

[0043] Figure 3 shows that the creep behavior of materials with different relative amounts of DA bonds as dissociable covalent bonds is quite similar at around room temperature, but as the temperature increases, materials with a higher relative amount of DA bonds as dissociable covalent bonds become more prone to creep.

[0044] It should be understood that the terms "crosslinked polymer," "polymer network," and "crosslinked polymer network" are used synonymously for polymer networks that have at least some degree of crosslinking.

[0045] As referred to herein, unless otherwise specified, the term “Diels-Alder reaction product of maleimide group and furan group” should be understood as the result of a Diels-Alder reaction between a furan group and a maleimide group, resulting in one of two isomers of a cycloadduct called a “Diels-Alder bond” or “DA bond.” As will be described in more detail below, Diels-Alder bonds can be formed by the reaction of a furan-functionalized prepolymer with a maleimide group-containing prepolymer, resulting in a polymer or polymer network containing the Diels-Alder reaction product of maleimide group and furan group as a dissociative crosslinking moiety. The Diels-Alder reaction that forms the Diels-Alder bond is an equilibrium reaction, making the resulting crosslinking bond dynamic. Within the dynamic network described above, the bond is constantly cleaved and reformed over time. The Diels-Alder bond is a strong covalent bond and possesses self-healing properties by being able to reversibly reform even if it is thermally dissociated or mechanically cleaved.

[0046] Scheme 1 is a schematic diagram of the Diels-Alder reaction between a furan group A and a maleimide group B, which yields the Diels-Alder reaction product. [ka] Scheme 1

[0047] When the Diels-Alder network is damaged, the Diels-Alder bond and hydrogen bond interactions are reversibly and locally cleaved, creating an active fracture surface. The hydrogen donors and acceptors resulting from the reversible mechanical cleavage of the Diels-Alder bond, as well as the newly formed furan and maleimide functional groups, autonomously reform the cleaved bond, thus restoring the polymer network structure and associated properties. To achieve this repair of the damaged area, the first step in the self-healing process involves bringing the fracture surfaces back into contact. Depending on the extent of the damage, for example, if the material is completely cleaved and two separate fragments are formed, manual or robotic intervention may be required to actively push both fracture surfaces back together. In such complete cleavage, both fractured fragments must be pushed back to initiate the repair process. In this case, it is important to push both fragments back as quickly as possible after the damage occurs.

[0048] As previously stated herein, the amount of Diels-Alder reaction products (DA bonds) of maleimide groups and furan groups as dissociable covalent bonds crossing the polymer network, relative to the total amount of crosslinking of the polymer network, which is the sum of the amount of DA bonds as dissociable covalent bonds and the amount of ester groups as associated covalent bonds, can affect the properties of the crosslinked polymer composition. In useful embodiments of the present invention, the amount of dissociable covalent bonds relative to the sum of dissociable covalent bonds and associated covalent bonds crossing the network is at least 5%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, or 99%. In certain embodiments, the present invention provides polymer network compositions as defined herein, wherein the amount of dissociative covalent bonds relative to the total amount of dissociative covalent bonds and associated covalent bonds crosslinking the network is at least 10%, preferably 20% to 99%, more preferably 30% to 95%, even more preferably 40% to 90%, and even more preferably 50% to 80%.

[0049] It has been found that the transesterification catalyst may be any catalyst known in the art that catalyzes the transesterification of an ester group and a hydroxyl group. In useful embodiments of the present invention, the transesterification catalyst may be a metal catalyst, an organic catalyst, an acid catalyst, a base catalyst, or any combination thereof. Preferred examples of transesterification catalysts include zinc acetylacetonate, zinc acetate, dibutyline oxide, tin(II)2-ethylhexanoate, triazabicyclodecene, 1-methylimidazole, and triphenylphosphine. In one embodiment, the present invention provides a polymer network composition as defined herein, in which the transesterification catalyst is selected from a list including zinc acetylacetonate, zinc acetate, dibutyline oxide, tin(II)2-ethylhexanoate, triazabicyclodecene, 1-methylimidazole, triphenylphosphine, and any combination thereof. In certain embodiments, the present invention provides a polymer network composition as defined herein, wherein the transesterification catalyst is a metal catalyst selected from a list comprising zinc acetylacetonate, zinc acetate, dibutyline oxide, tin(II) 2-ethylhexanoate, and any combination thereof. In another particular embodiment, the present invention provides a polymer network composition as defined herein, wherein the transesterification catalyst is an organic catalyst selected from a list comprising triazabicyclodecene, 1-methylimidazole, triphenylphosphine, and any combination thereof.

[0050] Furthermore, it has been found that when at least some of the ester groups providing associated covalent bonds in a double-crosslinked polymer network, and at least some of the hydroxyl groups contained in the double-crosslinked polymer network, are present as β-hydroxyesters, this can lead to improvements in the properties of the crosslinked polymer composition, such as improved repair dynamics. In certain embodiments, the present invention provides a polymer network composition as defined herein, in which at least some of the ester groups providing associated covalent bonds in a double-crosslinked polymer network, and at least some of the hydroxyl groups contained in the double-crosslinked polymer network, are present as β-hydroxyesters. In specific embodiments of the present invention, substantially all of the ester groups providing associated covalent bonds in a double-crosslinked polymer network are β-hydroxyesters. In more specific embodiments of the present invention, all of the ester groups providing associated covalent bonds in a double-crosslinked polymer network are β-hydroxyesters.

[0051] In the context of this invention, the term “at least a portion of” refers to a clear, non-zero portion of the subject it refers to. Thus, the term “at least a portion of” may refer to about 1%, 2%, 3%, 5%, 10%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, or substantially all of the subject it refers to, for example, about 90%, 95%, 99%, or even about 100%.

[0052] In the context of the present invention, the term “substantially all” means at least 90%, preferably at least 95%, more preferably at least 99%, and even more preferably 100% of the subject matter it refers to.

[0053] In the context of the present invention, β-hydroxyester means a chemically defined structure that can be obtained from the reaction of a carboxylic acid group with an oxirane group or an epoxy group, as schematically represented in Scheme 2. [ka] Scheme 2

[0054] Furthermore, it was found that if at least some of the ester groups providing the associated covalent bonds in the double-crosslinked polymer network, and at least some of the hydroxyl groups contained in the double-crosslinked polymer network, exist as β-hydroxyesters, and if the β-hydroxyesters are obtained by the reaction of a carboxylic acid group of a prepolymer with an oxirane group or epoxy group of another prepolymer (e.g., epoxidized vegetable oil), this may lead to an improvement in the properties of the crosslinked polymer composition, such as an improvement in self-healing kinetics.

[0055] In a useful embodiment of the present invention, at least a portion of the ester groups providing the associated covalent bonds of the double-crosslinked polymer network, and at least a portion of the hydroxyl groups included in the double-crosslinked polymer network, are of formula (I): [ka] (In the formula, R1 is -H, -C) 1~18 Alkyl and -C 2~18 Selected from alkenyl, and the above-C 1~18 Alkyl and -C 2~18 Each of the alkenyls can be arbitrarily and independently -halo, -OH, and -C. 1~6 Alkyl, -C 1~6 Alkenyl and -OC 1~6 It exists as a β-hydroxy ester (substituted with 1 to 3 substituents selected from alkyl groups).

[0056] Furthermore, it has become clear that if at least a portion of the furan groups of the Diels-Alder bond are connected to the polymer network via β-hydroxyester linkers, this may lead to improved properties of the crosslinked polymer composition, such as improved repair kinetics. While we do not wish to be bound by any theory, it is thought that the presence of hydrogen bonds close to the Diels-Alder bond may facilitate the repair process. It should be understood that the β-hydroxyester linkers connecting the furan groups of the Diels-Alder bond to the polymer network are not considered associative covalent bonds that provide crosslinking of the polymer network as defined in the first aspect of the present invention. In certain embodiments, the present invention provides a polymer network composition as defined herein, in which at least a portion of the furan groups of the Diels-Alder bond are connected to the polymer network via β-hydroxyester linkers. In specific embodiments of the present invention, substantially all of the furan groups of the Diels-Alder bond are connected to the polymer network via β-hydroxyester linkers. In more specific embodiments of the present invention, all of the furan groups of the Diels-Alder bond are connected to the polymer network via β-hydroxyester linkers.

[0057] Furthermore, it was revealed that if at least a portion of the furan groups in the Diels-Alder bond are connected to the polymer network via a β-hydroxyester linker, and the β-hydroxyester linker is obtained from the reaction of a carboxylic acid group of the prepolymer with a furan introduction reagent containing an oxirane group or epoxy group such as furan glycidyl ether, this may lead to improvements in the properties of the crosslinked polymer composition, such as improved repair dynamics.

[0058] In a useful embodiment of the present invention, at least a portion of the furan groups of the Diels-Alder bond are of formula (II): [ka] (In the formula, R1 is -H, -C1~18 Alkyl and -C 2~18 Selected from alkenyl, the -C 1~18 Alkyl, and the -C 2~18 Each of the alkenyls can be arbitrarily and independently -halo, -OH, and -C. 1~6 Alkyl, -C 1~6 Alkenyl and -OC 1~6 Substituted with 1 to 3 substituents selected from alkyl groups, Y is -C 1~6 Selected from alkylene-, -O-, -C(O)O-, and -OC(O)-, X1 and X2 are independently -C 1~6 Alkyl-, -C 2~6 Alkenyl-, and -C 1~6 Selected from alkyl-O- and the above-C 1~6 Alkyl-, above -C 2~6 Alkenyl-, and the above-C 1~6 Each alkyl-O- group can be arbitrarily and independently -halo, -OH, or -C. 1~6 Alkyl, -C 1~6 Alkenyl and -OC 1~6 The polymer network is connected via a β-hydroxyester linker (which is substituted with 1 to 3 substituents selected from alkyl groups).

[0059] It has become clear that the presence of radical scavengers in a crosslinked polymer composition can lead to improved properties of the crosslinked polymer composition, for example, by at least partially suppressing irreversible homopolymerization of maleimide groups. In certain embodiments, the present invention provides polymer network compositions as defined herein, further comprising radical scavengers. Any radical scavenger known in the art that can suppress monomer homopolymerization can be suitably used. Preferred examples include hydroquinone, butylated hydroxytoluene, 4-tert-butylcatechol, and methyl-p-benzoquinone. In useful embodiments of the present invention, the polymer network composition as defined herein further comprises radical scavengers selected from a list including hydroquinone, butylated hydroxytoluene, 4-tert-butylcatechol, methyl-p-benzoquinone, and any combination thereof.

[0060] As described above in this specification, according to a second aspect, the present invention is a method for preparing a polymer network composition as defined herein, comprising a double-crosslinked polymer network, wherein the method is a) A step of preparing a first prepolymer containing a carboxylic acid group, b) A step of functionalizing the first portion of the carboxylic acid group of the first prepolymer with a furan introduction reagent in the presence of a transesterification catalyst, thereby obtaining a furan-functionalized prepolymer containing the second portion of the carboxylic acid group, c) A step of adding a second prepolymer containing an oxirane group or an epoxy group, and a third prepolymer containing a maleimide group to the furan-functionalized prepolymer, thereby obtaining a prepolymer mixture. d) A step of stirring the prepolymer mixture at a high temperature to obtain a polymer network composition, Includes, The present invention provides a method in which the first portion is at least 5% of the total amount of carboxylic acid groups of the first prepolymer.

[0061] A method according to a second embodiment has been found to provide a crosslinked polymer composition as defined herein, wherein a first prepolymer containing carboxylic acid groups is first reacted with a furan introduction reagent in the presence of a transesterification catalyst to functionalize the first portion of the carboxylic acid groups, and then the furan-functionalized prepolymer, still containing a second portion of carboxylic acid groups, is reacted with a second prepolymer containing oxirane or epoxy groups and a third prepolymer containing maleimide groups. The second portion of the carboxylic acid groups of the furan-functionalized prepolymer reacts with the oxirane or epoxy groups of the second prepolymer to provide ester groups and hydroxyl groups, particularly β-hydroxyester groups, as associated covalent bonds that crosslink the network. The furan groups of the furan-functionalized prepolymer can react with the maleimide groups of the third prepolymer to yield a Diels-Alder reaction product of maleimide and furan groups as dissociative covalent bonds that similarly crosslink the network. Together, the first and second portions of the carboxylic acid groups constitute substantially all of the carboxylic acid groups of the first prepolymer.

[0062] Furthermore, it has been found that crosslinking a furan-functionalized prepolymer, a second prepolymer containing an oxirane group or an epoxy group, and a third prepolymer containing a maleimide group at a high temperature in step d) of the method as defined herein results in an efficient reaction for obtaining the polymer network composition according to the present invention. In one embodiment, the present invention provides a method for preparing the polymer network composition as defined herein, in which the prepolymer mixture in step d) is stirred at a temperature of at least 50°C, preferably at least 70°C, and more preferably 100°C to 150°C. In another embodiment, the present invention provides a method for preparing the polymer network composition as defined herein, in which the prepolymer mixture in step d) is stirred at a high temperature for at least 2 hours, preferably 4 to 16 hours.

[0063] Scheme 3 provides a schematic diagram of the preparation of a polymer network composition according to embodiments of the present invention, wherein a first prepolymer containing carboxylic acid groups (prepolymer 1) is partially functionalized with furan groups (the first portion of the carboxylic acid group) by reaction with furfurylglycidyl ether (FGE) in the presence of a transesterification catalyst, and then reacted with a second prepolymer containing oxirane or epoxy groups (prepolymer 2) to yield associated covalent bonds (ACBs), and then reacted with a third prepolymer containing maleimide groups (prepolymer 3) to yield dissociative bonds (DCBs), all of which crosslink the polymer network.

[0064] Depending on the stoichiometry of the carboxylic acid groups of the first prepolymer and the furan introduction reagent, the amount of dissociable covalent bonds in the crosslinked polymer composition relative to the total of dissociable and associated covalent bonds crosslinking the network may vary. For example, if the first portion of carboxylic acid groups to be reacted with the furan introduction reagent is 5% of the total amount of carboxylic acid groups in the first prepolymer, the furan-functionalized prepolymer contains a second portion of the remaining 95% of carboxylic acid groups. When this furan-functionalized prepolymer is reacted with the second and third prepolymers at high temperature, substantially all of the furan groups in the furan-functionalized prepolymer react with the maleimide groups of the third prepolymer, and substantially all of the remaining carboxylic acid groups in the furan-functionalized prepolymer, i.e., the second portion of carboxylic acid groups, react with the oxirane or epoxy groups of the second prepolymer to provide a polymer network composition encompassed by the present invention, where the amount of dissociable covalent bonds relative to the total of dissociable and associated covalent bonds crosslinking the network is 5%. [ka] prepolymer Catalyst Scheme 3

[0065] To react, for example, 5% of the total amount of carboxylic acid groups in the first prepolymer with furan groups or to functionalize it with furan groups, the stoichiometry of the first prepolymer and the furan-introducing reagent is determined by the molar equivalents of the available carboxylic acid groups versus the molar equivalents of the furan-introducing reagent. Similarly, the stoichiometry of the second prepolymer may be selected to react substantially all of the furan groups in the furan-functionalized prepolymer, i.e., the ratio of furan groups to maleimide groups is about 1:1, and in this case too, it is determined by molar equivalents. Likewise, the stoichiometry of the third prepolymer may be selected to react substantially all of the remaining carboxylic acid groups in the furan-functionalized prepolymer, i.e., the ratio of carboxylic acid groups to oxirane or epoxy groups is about 1:1, and in this case too, it is determined by molar equivalents.

[0066] As previously stated herein, the amount of Diels-Alder reaction products of maleimide groups and furan groups as dissociable covalent bonds crosslinking the polymer network, relative to the total amount of covalent crosslinks in the polymer network, can affect the properties of the crosslinked polymer composition. In useful embodiments of the present invention, the first portion of carboxylic acid groups of the first prepolymer relative to the total amount of carboxylic acid groups of the first polymer is at least 5%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, or 99%. In certain embodiments, the present invention provides a method for preparing a polymer network composition as defined herein, wherein the first portion of carboxylic acid groups of the first prepolymer relative to the total amount of carboxylic acid groups of the first polymer is at least 10%, preferably 20% to 99%, more preferably 30% to 95%.

[0067] In a useful embodiment of the present invention, at least 0.5 mol% of a transesterification catalyst, relative to the molar equivalent of carboxylic acid groups in the first prepolymer, is used in step b) of the method as defined herein. In a particular embodiment, the present invention provides a method for preparing a polymer network composition as defined herein, wherein the amount of transesterification catalyst applied in step b) is at least 0.5 mol%, preferably at most 15 mol%, more preferably 1 mol% to 10 mol%, and even more preferably 3 mol% to 8 mol%, relative to the molar equivalent of carboxylic acid groups in the first prepolymer.

[0068] As described herein, the addition of radical scavengers to a crosslinked polymer composition may lead to improved properties of the crosslinked polymer composition, for example, by at least partially suppressing irreversible homopolymerization of maleimide groups. In one embodiment, the present invention provides a method for preparing a polymer network composition as defined herein, in which the radical scavenger is added in any one step before the prepolymer mixture is stirred at a high temperature. In a particular embodiment, the present invention provides a method for preparing a polymer network composition as defined herein, in which the radical scavenger is added in step b) or step c).

[0069] Furthermore, it has been found that prepolymers containing maleimide groups having a functional value of at least 2 can lead to improved properties of crosslinked polymer compositions. Unless otherwise specified, the functional value should be understood as the number of maleimide groups on the maleimide group-containing prepolymer. In one embodiment, the present invention provides a method for preparing a polymer network composition as defined herein, wherein the maleimide group-containing prepolymer has a functional value of at least 2. In a particular embodiment, the present invention provides a method for preparing a polymer network composition as defined herein, wherein the maleimide group-containing prepolymer is bismaleimide.

[0070] In another embodiment, the present invention provides the use of polymer network compositions as defined herein.

[0071] The polymer network compositions defined herein have proven to be particularly suitable for use as self-healing materials. Furthermore, the crosslinked polymer compositions defined herein have proven to be particularly suitable for use in the field of robotics, more specifically in subfields of soft robotics. It has also been found that the polymer network compositions defined herein provide shape memory properties and can therefore be used as shape memory materials.

[0072] Where used herein, unless otherwise specified, the term “soft robotics” shall be understood as a subfield of robotics that includes the construction of robotic components and robots from various types of materials with properties similar to those found in living organisms. These materials often require a certain degree of flexibility and adaptability depending on the specific purpose.

[0073] Shape memory is a well-known term in the relevant technical field, referring to the ability of certain materials to "remember" their original shape and return to that shape after deformation. This property is often induced through phase transitions in the material, such as changes in temperature or stress. Because these materials can undergo reversible deformation when subjected to specific stimuli such as heating or cooling, they are highly valued in situations where precise shape changes are required.

[0074] It has become clear that the shape memory properties of polymer network compositions as defined herein may be due to a combination of dissociative and associative covalent bonds in the polymer network compositions provided herein. More specifically, although we do not wish to be bound by any theory, it has become clear that shape memory of polymer network compositions as defined herein may be possible by relaxing only the dissociative bonds while the network is held in place by the associative bonds. The thus dissociated bonds allow sufficient mobility of the polymer chains to change shape, and when the material cools, new dissociative bonds may form to maintain the new shape. When the sample is heated again, the stress stored in the vitrimer portion of the network is released, and the sample can regain its original shape.

[0075] In one embodiment, the present invention provides the use of a polymer network composition as defined herein as a self-healing material. In a further embodiment, the present invention provides the use of a polymer network composition as defined herein as a shape memory material. In another embodiment, the present invention provides the use of a polymer network composition as defined herein in the manufacture of 1D, 2D, or 3D structures. In a particular embodiment, the present invention provides the use of a polymer network composition as defined herein in the manufacture of robot parts, seals, gaskets, or tires. In yet another embodiment, the present invention provides the use of a polymer network composition as defined herein in a manufacturing method selected from filament extrusion, extrusion-based printing techniques, selective laser sintering, injection molding, compression molding, casting, and soft lithography. In a particular embodiment, the present invention provides the use of a polymer network composition as defined herein in an extrusion-based printing technique selected from a filament melting method, a direct ink writing method, and the like.

[0076] Furthermore, it was found that the optimal amount of dissociative covalent bonds relative to the total number of dissociative and associative covalent bonds crosslinking the network may vary depending on the intended application. In other words, the polymer network compositions defined herein can be tailored to specific applications.

[0077] For example, in 3D printing, it has been found that improved results can be obtained when the amount of dissociative covalent bonds is at least 60%, preferably 60% to 90%, and more preferably 65% ​​to 75%, relative to the total amount of dissociative covalent bonds and associated covalent bonds bridging the network. While we do not wish to be bound by any theory, it is thought that dissociative Diels-Alder bonds allow the network to flow within the nozzle and improve interlayer adhesion, while associated ester bonds maintain the shape of the sample during deposition.

[0078] For example, in shape memory materials, it has been found that improved results can be obtained when the amount of dissociative covalent bonds relative to the total amount of dissociative covalent bonds and associated covalent bonds bridging the network is at least 30%, preferably 40% to 70%, and more preferably 40% to 60%. While we do not wish to be bound by any theory, it is thought that these ratios of dissociative and associated bonds can provide an improved balance in which the network shape is maintained by associated bonds while mainly relaxing the dissociative bonds.

[0079] In yet another embodiment, the present invention provides a 1D structure, a 2D structure, or a 3D structure comprising a polymer network composition as defined herein. In a particular embodiment, the present invention provides a 1D structure, a 2D structure, or a 3D structure as defined herein, the structure being selected from robot parts, seals, gaskets, or tires.

[0080] The compounds of the present invention can be prepared according to the methods (or more) presented in the following examples, but those skilled in the art will understand that these are merely illustrative examples of the present invention, and that the compounds of the present invention can be prepared by any of several standard synthesis processes commonly used by those skilled in the field of organic chemistry.

[0081] As described above in this specification, the self-healing properties of the crosslinked polymer composition depend, on the one hand, on the Diels-Alder reaction product of maleimide groups and furan groups as dissociative covalent crosslinking sites, and on the other hand, on the other hand, on the other hand, on the other hand, on ester groups as associated covalent crosslinking sites. [Examples]

[0082] material Succinic anhydride (SA), itaconic anhydride (IA), maleic anhydride (MA), castor oil (CO; 164 mg KOH / g), zinc(II) acetylacetonate, 1,1'-(methylenedi-4,1-phenylene)bismaleimide (DPBM), and 4-tert-butylcatechol were obtained from Sigma Aldrich. Furfuryl glycidyl ether (FGE) was obtained from BLD Pharmatech GmbH (Kaiserslautern, Germany). Epoxidized soybean oil (SO) was obtained from Varteco (Santa Fe, Argentina). BMI-689 was obtained from Designer molecules (Willow Creek, San Diego). Pripol 1040 was obtained from Croda. Unless otherwise noted, all reagents were used in their original condition.

[0083] analysis The Bruker Avance DRX 250 allows for an aperture frequency of 250 MHz. 1 1H NMR was performed. The analysis was carried out at room temperature using CDCl3 as the solvent and TMS as the internal standard. The concentration of the sample was 10 mg / m³.

[0084] Fourier transform infrared (FTIR) spectroscopy was performed at ambient temperature using a Thermo Scientific Nicolet 6700 FTIR spectrophotometer with OMNIC as the software package. All spectra were recorded at 4000 cm⁻¹. -1 ~600 cm -1 The average is taken from 32 scans recorded.

[0085] Differential scanning calorimetry (DSC) was performed using a TA Instruments Discovery DSC equipped with a refrigerated cooling system (RCS). All experiments were conducted in an unsealed environment within a Tzero aluminum pan, using nitrogen as the purge gas and a heating / cooling rate of 5°C / min.

[0086] Dynamic mechanical analysis (DMA) was performed using a TA Instruments DMA Q800 equipped with a nitrogen gas cooling accessory. Stress-strain tensile tests were performed at room temperature using film tension clamps. Rectangular specimens with a thickness of 1.25 mm and a width of 5 mm were clamped with a distance of 5 mm between the clamps and strained at a rate of 60% / min. Young's modulus was determined in the initial linear region of the stress-strain curve (0% to 1% strain).

[0087] Dynamic rheometry was performed using a Discovery Hybrid Rheometer (DHR2) from TA Instruments. The sample was cut into a circular shape and placed between 8 mm diameter parallel aluminum plates. Three tests were performed on the material. 1. The sample was subjected to a 1% vibrational strain at different frequencies of 0.312 Hz, 0.562 Hz, 1.0 Hz, 1.778 Hz, and 3.125 Hz. Simultaneously, it was subjected to a temperature gradient from 40°C to 120°C to determine the gelation transition temperature. 2. The sample was subjected to a 1% vibrational strain with a frequency gradient of 0.01 rad / s to 300 rad / s at temperatures of 90°C, 120°C, 140°C, and 160°C. 3. Stress-relaxation experiments were conducted at different temperatures (200°C to 90°C) within the linear viscoelastic region using a constant shear strain of 1%.

[0088] synthesis Example 1. Preparation of a prepolymer having a carboxylic acid group Ring-opening esterification of castor oil was performed using maleic anhydride (MA). The reaction was carried out under an N2 atmosphere, without solvent, and with magnetic stirring. A molar ratio of hydroxyl groups of castor oil to anhydride was 1:1. The esterification reaction was carried out at 100°C for 24 hours. The resulting maleinized castor oil (mCO) was used without any further purification.

[0089] Example 2. Preparation of a prepolymer having a carboxylic acid group Ring-opening esterification of castor oil was performed using itaconic anhydride (IA). The reaction was carried out under an N2 atmosphere, without solvent, and with magnetic stirring. A molar ratio of hydroxyl groups in castor oil to anhydride was 1:1. The esterification reaction was carried out at 100°C for 24 hours. The resulting itaconized castor oil (iCO) was used without any further purification.

[0090] Example 3. Preparation of a prepolymer having a carboxylic acid group Ring-opening esterification of castor oil was performed using succinic anhydride (SA). The reaction was carried out under an N2 atmosphere, without solvent, and with magnetic stirring. A molar ratio of hydroxyl groups of castor oil to anhydride was 1:1. The esterification reaction was carried out at 130°C for 24 hours. The resulting succinized castor oil (sCO) was used without any further purification.

[0091] Example 4. A furan-functionalized prepolymer is obtained by partially functionalizing a prepolymer containing a carboxylic acid group with a furan group. Furfuryl glycidyl ether (FGE) was directly mixed with mCO prepared according to Example 1. The molar ratio of FGE to the carboxylic acid groups of mCO varied from 0.05 to 0.95. 5 mol% of Zn(II) acetylacetonate was added to the mixture relative to the carboxylic acid groups of mCO. The functionalization reaction was carried out at 100°C for 5 hours under an N2 atmosphere, without solvent, and with magnetic stirring. The resulting furan-functionalized maleated castor oil (FmCO) was used in the following steps without further purification.

[0092] Table 1 shows an overview of Examples 4a to 4e, which represent compositions with different molar ratios of FGE to carboxylic acid groups in mCO.

[0093] Table 1. Composition data of Examples 4a to 4e [Table 1]

[0094] Example 5. A furan-functionalized prepolymer is obtained by partially functionalizing a prepolymer containing a carboxylic acid group with a furan group. Furfurylglycidyl ether (FGE) was directly mixed with iCO prepared according to Example 2. The molar ratio of FGE to the carboxylic acid groups of iCO varied from 0.05 to 0.95. 5 mol% of Zn(II) acetylacetonate was added to the mixture relative to the carboxylic acid groups of iCO. The functionalization reaction was carried out overnight at 120°C under an N2 atmosphere with magnetic stirring and no solvent. The resulting furan-functionalized itaconized castor oil (FiCO) was used in the following steps without further purification.

[0095] Table 2 shows an overview of Examples 5a to 5e, which represent compositions with different molar ratios of FGE to the carboxylic acid group of iCO.

[0096] Table 2. Composition data of Examples 5a to 5e [Table 2]

[0097] Example 6. A furan-functionalized prepolymer is obtained by partially functionalizing a prepolymer containing a carboxylic acid group with a furan group. Furfuryl glycidyl ether (FGE) was directly mixed with sCO prepared according to Example 3. The molar ratio of FGE to the carboxylic acid groups of sCO varied from 0.05 to 0.95. 5 mol% of Zn(II) acetylacetonate was added to the mixture relative to the carboxylic acid groups of sCO. The functionalization reaction was carried out at 100°C for 5 hours under an N2 atmosphere with magnetic stirring and no solvent. The resulting furan-functionalized succinic castor oil (FsCO) was used in the following steps without further purification.

[0098] Table 3 shows an overview of Examples 6a to 6e, which represent compositions with different molar ratios of FGE to carboxylic acid groups of sCO.

[0099] Table 3. Composition data of Examples 6a to 6e [Table 3]

[0100] Example 7. A furan-functionalized prepolymer is obtained by partially functionalizing a prepolymer containing a carboxylic acid group with a furan group. Furfurylglycidyl ether (FGE) was directly mixed with Pripol 1040. The molar ratio of FGE to the carboxylic acid groups of Pripol 1040 varied from 0.3 to 0.85. 5 mol% of Zn(II) acetylacetonate was added to the mixture relative to the carboxylic acid groups of Pripol 1040. The functionalization reaction was carried out at 100°C for 5 hours under an N2 atmosphere, without solvent, and with magnetic stirring. The resulting furan-functionalized Pripol 1040 (FP1040) was used in the following steps without further purification.

[0101] Table 4 outlines Examples 7a to 7e, which represent compositions with different molar ratios of FGE to the carboxylic acid groups of Pripol 1040.

[0102] Table 4. Composition data of Examples 7a to 7e [Table 4]

[0103] Example 8. Reaction of a furan-functionalized prepolymer with a second prepolymer and a third prepolymer, each containing an oxirane group or an epoxy group and a maleimide group, respectively. FmCO, FiCO, FsCO, and FP1040, prepared according to Examples 4 to 7, were crosslinked with epoxidized soybean oil (ESO) and one of two different bismaleimides: 1,1'-(methylenedi-4,1-phenylene)bismaleimide (DPBM) and a commercially available low-viscosity bismaleimide (BMI-689).

[0104] To prepare the network, furan functionalizing materials (FmCO, FiCO, FsCO, and FP1040) were mixed with the following: 1. Bismaleimide in a 1:1 molar ratio to furan groups in a furan-functionalized prepolymer; 2. Epoxy soybeans in a 1:1 molar ratio with the remaining carboxylic acid groups of the furan-functionalized prepolymer; 3. 1% by weight of 4-tert-butylcatechol relative to the total mass of the prepolymer mixture.

[0105] Table 5 shows an overview of the compositions of Examples 8a to 8e.

[0106] Table 5. Composition data of Examples 8a to 8e [Table 5]

[0107] The mixture was heated to 130°C and stirred with a stirring magnet until it became transparent. The mixture was then poured into a PTFE mold and cured overnight in a 130°C oven. Finally, the material was annealed in a vacuum oven at 180°C for 1 hour.

[0108] Comparative Example A. A furan-functionalized prepolymer is obtained by completely functionalizing a prepolymer containing a carboxylic acid group with a furan group. A furan-functionalized prepolymer was prepared according to Example 7 by reacting Pripol 1040 (38.09 g) with FGE (19.84 g) in the presence of Zn(acac)2 (1.69 g), with a ratio of FGE to carboxylic acid groups of 1. The polymer network was prepared according to Example 8 by reacting the furan-functionalized prepolymer with BMI-689 (40.38 g) alone. This yielded a polymer network composition having only dissociable covalent bonds (100% DA bonds as DCBs).

[0109] Comparative Example B. Complete functionalization of a carboxylic acid group-containing prepolymer with a prepolymer containing an oxirane group or an epoxy group. The polymer network was prepared according to Example 8 by reacting unfuran-functionalized Pripol 1040 (53.93 g) with epoxidized soybean oil (47.87 g) in the presence of Zn(acac)2 (2.40 g). This yielded a polymer network composition having only associated covalent bonds (0% DA bonds as DCBs).

[0110] 3D printing Different polymer network compositions according to embodiments of the present invention (Examples 8a to 8c) and Comparative Example A were tested by 3D printing using a Lulzbot Taz 6 3D printer with a Pellet Extruder v4 printer head from Mahor.xyz. G-code files were prepared using Cura LulzBot Edition 3.6.23. The parameters used in the printing tests are shown in Table 6.

[0111] Table 6. Printing Parameters [Table 6]

[0112] A polymer network composition having 70% DA bonds as dissociable covalent bonds (Example 8b) was found to be capable of printing a hollow structure 2 cm in height and to provide the best printing results. Polymer network compositions with 85% DA bonds (Example 8a) and 100% DA bonds (Comparative Example A), respectively, were found to be more liquid and difficult to maintain the printed structure, while a polymer network composition with 60% DA bonds (Example 8c) was found to be difficult to extrude.

[0113] shape memory To demonstrate the shape memory properties of the polymer network composition according to the present invention, a rectangular sample prepared according to Example 8d, also called the original shape, was curled in a glass vial, heated in an oven at 110°C for 30 minutes, and cooled to provide a curled sample, also called the temporary shape. Shape recovery was performed by heating the curled sample in an oil bath at 110°C for 10 minutes. Figure 4 schematically shows the various steps described in this section with respect to demonstrating the shape memory properties, where Tc represents the temperature above which at least some dissociable bonds dissociate, enabling the mobility of the polymer chain.

[0114] Based on dynamic mechanical analysis (data not shown) of samples with different amounts of dissociable covalent bonds, namely 30% (Example 8e), 50% (Example 8d), and 70% (Example 8b), it was found that samples with 30% or 50% dissociable covalent bonds had a better ability to maintain their temporary shape compared to the sample with 70% dissociable covalent bonds. Based on the same analysis, it was found that samples with 50% or 70% dissociable covalent bonds had a better ability to return to their original shape compared to the sample with 30% dissociable covalent bonds. [Explanation of Symbols]

[0115] Drawing translation Figure 1 Time (s) Time (s) Comparison at 140℃ Example Figure 2 Storage modulus (G') Comparative example Example Temperature (℃) Temperature (℃) Figure 3 Strain (%) Distortion (%) Comparative example Example Time (min) Figure 4 Sample at RT (Room Temperature) heating heating Shape fixing cooling cooling fixed shape shape recovery

Claims

1. A polymer network composition comprising a transesterification catalyst and a polymer network double-crosslinked by a Diels-Alder reaction product of a maleimide group and a furan group as dissociable covalent bonds and ester groups as associated covalent bonds, wherein the double-crosslinked polymer network further comprises hydroxyl groups, at least a portion of the ester groups providing associated covalent bonds of the double-crosslinked polymer network and at least a portion of the hydroxyl groups contained in the double-crosslinked polymer network exist as β-hydroxyesters, and the amount of dissociable covalent bonds relative to the total of dissociable covalent bonds and associated covalent bonds crosslinking the network is at least 5%.

2. The polymer network composition according to claim 1, wherein the amount of dissociative covalent bonds relative to the total of dissociative covalent bonds and associated covalent bonds crosslinking the network is at least 10%, preferably 20% to 99%, more preferably 30% to 95%, even more preferably 40% to 90%, and even more preferably 50% to 80%.

3. The aforementioned β-hydroxyester is of formula (I): 【Chemistry 1】 (In the formula, R 1 -H, -C 1～18 Alkyl and -C 2～18 Selected from alkenyls, and the -C 1～18 Alkyl and the -C 2～18 Each of the alkenyls can be arbitrarily and independently -halo, -OH, and -C. 1～6 Alkyl, -C 1～6 Alkenyl and -OC 1～6 A polymer network composition according to claim 1 or 2, represented by (substituted with one to three substituents selected from alkyl groups).

4. The polymer network composition according to any one of claims 1 to 3, wherein at least a portion of the furan groups of the Diels-Alder bond are connected to the polymer network via a β-hydroxyester linker.

5. At least a portion of the furan group of the Diels-Alder bond is of formula (II): 【Chemistry 2】 (In the formula, R 1 is selected from -H, -C 1～18 alkyl, and -C 2～18 alkenyl, and each of the -C 1～18 alkyl, and the -C 2～18 alkenyl is optionally and independently substituted with 1 to 3 substituents selected from -halo, -OH, -C 1～6 alkyl, -C 1～6 alkenyl, and -O-C 1～6 alkyl, and Y is -C 1～6 Selected from alkylene-, -O-, -C(O)O-, and -OC(O)-, X 1 and X 2 -C 1～6 Alkyl-, -C 2～6 Alkenyl-, and -C 1～6 Selected from alkyl-O-, and the -C 1～6 Alkyl-, the aforementioned -C 2～6 Alkenyl-, and the aforementioned -C 1～6 Each alkyl-O- group can be arbitrarily and independently -halo, -OH, or -C. 1～6 Alkyl, -C 1～6 Alkenyl and -OC 1～6 The polymer network composition according to any one of claims 1 to 4, wherein the polymer network is connected via a β-hydroxyester linker (which is substituted with one to three substituents selected from alkyl groups).

6. A polymer network composition according to any one of claims 1 to 5, further comprising a radical scavenger.

7. The polymer network composition according to any one of claims 1 to 6, wherein the transesterification catalyst is selected from zinc acetylacetonate, zinc acetate, dibutyline oxide, tin(II) 2-ethylhexanoate, triazabicyclodecene, 1-methylimidazole, triphenylphosphine, or any combination thereof.

8. A method for preparing a polymer network composition according to any one of claims 1 to 7, comprising a double crosslinked polymer network, wherein the method is a) A step of preparing a first prepolymer containing a carboxylic acid group, b) A step of functionalizing the first portion of the carboxylic acid group of the first prepolymer with a furan introduction reagent in the presence of a transesterification catalyst, thereby obtaining a furan-functionalized prepolymer containing the second portion of the carboxylic acid group, c) A step of adding a second prepolymer containing an oxirane group or an epoxy group, and a third prepolymer containing a maleimide group to the furan-functionalized prepolymer, thereby obtaining a prepolymer mixture. d) A step of stirring the prepolymer mixture at a high temperature to obtain the polymer network composition, Includes, A method wherein the first portion is at least 5% of the total amount of carboxylic acid groups of the first prepolymer.

9. The method according to claim 8, wherein a radical scavenger is added in any one step before the prepolymer mixture is stirred at the high temperature.

10. The method according to claim 8 or 9, wherein the prepolymer containing the maleimide group has at least 2 functional values, and in particular the prepolymer containing the maleimide group is bismaleimide.

11. Use of the polymer network composition according to any one of claims 1 to 7 as a self-healing material.

12. Use of the polymer network composition according to any one of claims 1 to 7 in the manufacture of 1D structures, 2D structures or 3D structures, particularly in the manufacture of robot parts or tires.

13. Use of the polymer network composition according to any one of claims 1 to 7 in a manufacturing method selected from the list, including filament extrusion, extrusion-based printing techniques, selective laser sintering, injection molding, compression molding, cast molding, and soft lithography.

14. The use of the polymer network composition according to claim 13, wherein the extrusion-based printing technique is selected from a list including a filament dissolution method, a direct ink writing method, and the like.

15. A 1D structure, a 2D structure, or a 3D structure comprising the polymer network composition according to any one of claims 1 to 7.

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