Self-repair polymers

Abstract

The present invention relates to self-healing polymers and their use in various fields such as additive manufacturing and robotics. In addition, the present invention relates to methods of making the self-healing polymers and compositions and structures comprising the polymers.

Description

Field of the Invention

[0001] The present invention relates to self-healing polymers and their applications in various fields such as additive manufacturing and robotics. In addition, the present invention relates to methods of preparing said self-healing polymers and compositions and structures comprising said polymers. Background of the Invention

[0003] Any material applied to any type of application field is prone to a certain degree of degradation over time. This degradation may be caused by, for example, environmental conditions, damage that occurs during operation, or other external factors. Depending on the type of application, different types of materials will be suitable and are usually selected based on their material-specific properties (e.g., weight, rigidity, flexibility, stability, conductivity, porosity, etc.). When the material is damaged (e.g., material cracks, ruptures, cuts, scratches, etc.), external intervention is often required to repair the damage. If the damage is too severe or it is unfavorable to repair the damage (e.g., due to high costs, long repair times), it may be necessary to replace the material in part or in full. In short, the material may be damaged, and over time it may be necessary to repair the material and the parts made thereof to maintain functionality. Therefore, materials that are essentially able to correct damage can reduce costs and are very beneficial, especially in those fields where parts are often damaged or those fields where repair or maintenance is difficult or impossible.

[0004] Robotics, and more specifically the application of soft grippers, is a classic example of a field that is susceptible to damage during use. Soft grippers can be deployed in the fields of agriculture and food packaging (this is achieved through embodied intelligence), taking on the role of the agent's body in generating behavior, which allows the control to be outsourced to intelligent design. When used for fruit and vegetable picking, these soft grippers come into close contact with sharp objects (e.g., sharp branches, thorns, plastic, or glass). As a result, macroscopic damage (e.g., punctures, cuts, and cracks) can occur over time and negatively affect the performance of these grippers. Typically, these soft grippers are made of relatively cheap materials such as elastomers (e.g., silicone, polyurethane), so damaged grippers need to be replaced rather than repaired. However, this requires manual intervention that consumes a lot of time, money, and a large amount of new resources. In addition, it generates waste over time, which has a significant ecological impact. Due to these drawbacks, the use of self-healing materials can be seen as a promising alternative to minimize external intervention and allow damaged materials to be repaired, making material replacement redundant.

[0005] Robots are also used in remote applications, such as search and recovery in aerospace or marine environments or environmental surveys, where it is difficult to repair or replace damaged parts. Soft robots can bend, stretch, and twist around obstacles, which makes them safer, but they have the disadvantage of being more difficult to control due to their unlimited number of degrees of freedom.

[0006] Self-healing materials already exist today and have the ability to repair damage without replacing these materials. However, many disadvantages are known. For extrinsic repair systems, which rely on the encapsulation of the repair agent, the repair action may often only occur a limited number of times at the same damage location. In addition, the repair mechanisms are often not suitable for repairing relatively large damage. Moreover, these repair mechanisms are only applicable to rigid materials and do not provide very beneficial flexibility, such as in soft gripper structures. In many intrinsic repair systems, the material strength is often insufficient to produce larger 2D or 3D structures with sufficient strength and maintain structural integrity.

[0007] A specific type of self-healing material is a Diels-Alder (DA) polymer network, which provides a solution to most of the above-mentioned shortcomings. This network is based on a reversible Diels-Alder reaction between functionalized dienes (e.g., furans) and dienophiles (e.g., maleimide) groups to achieve the self-healing properties. The cross-linking process within these polymers is the most important aspect of the special self-healing properties of the polymers based on the Diels-Alder reaction, which is based on strong covalent bonds and allows the production of 1D, 2D or 3D structures with sufficient mechanical strength even after self-healing. The applicant's previous work (EP20192135.0) led to the development of a new type of polymer network based on the Diels-Alder reaction, which has self-healing capabilities even at room temperature and below, without external intervention.

[0008] However, as Hawkes et al. (Sci. Robot. 2021, 6, p6049) recently pointed out, before soft robotics can be widely used, several key challenges must be overcome, one of which is sustainability. Currently, soft robots do not provide a sustainable solution because (i) the materials used to make them are fossil-based and (ii) they are also often made of chemically cross-linked materials with poor recyclability and biodegradability. The key to successful sustainable design lies in starting with good material selection. Therefore, as Kaltenbrunner et al. (Adv. Mater. 2021, 33, 2004413) suggested in their review, the field of soft robotics and materials science should advance together, both to develop new materials that contribute to a more sustainable future and to improve existing materials and reduce their ecological footprint. Soft robotics' reliance on fossil-based, non-degradable polymer materials poses obvious environmental problems. Although bioplastics production capacity is growing at a fairly fast pace, from about 2.1 million tonnes in 2018 to about 2.62 million tonnes in 2023, they account for less than 1% of the 335 million tonnes of plastic produced each year. Moreover, the use of renewable feedstocks primarily targets resource issues, not necessarily waste issues.

[0009] In the literature, several attempts have been made to improve the sustainability of self-healing Diels-Alder networks. Yoshie et al. (Polym.Degrad.Stab.2019, 161, 13) developed bio-based polyesters that recovered up to 18 MPa of fracture stress after gentle heating at 50 °C for 5 days. Gandini et al. (Eur.J.Lipid Sci.Technol.2018, 120, 1700091) focused on the use of vegetable oils, highlighting the potential use of several types of oils and furan monomers in self-healing applications. Feng et al. (ACS Appl.Polym.Mater.2019, 1, 169) functionalized epoxidized natural rubber with furfurylamine to obtain a material that can be reprocessed and recover 87% after heating at 150 °C. Recently, Wu et al. (Green Chem. 2021, 23, 552) reported the synthesis of a self-healing CO2-based polyurethane-urea DA that could achieve self-healing efficiency of up to 94% after heating to 120°C for 10 min and 60°C for 24 h. In all these cases, the focus was on only one or two sustainability aspects, while others were neglected.

[0010] Therefore, the object of the present invention is to address these problems from a more comprehensive perspective by providing new sustainable self-healing polymers, thereby optimizing the renewability, biodegradability and recyclability of these polymers as a whole. SUMMARY OF THE INVENTION

[0012] According to a first aspect, the present invention provides a polymer based on a Diels-Alder reaction comprising the reaction product of a polymaleimide monomer unit and a furan-functionalized prepolymer;

[0013] The furan-functionalized prepolymer is characterized by having a prepolymer backbone comprising substituents having a central moiety of formula (I):

[0014]

[0015] Where R 1 Yes - H;

[0016] wherein at least one furan-functionalized side chain is attached to the central moiety; and

[0017] The prepolymer backbone is polyester based.

[0018] According to one embodiment of the present invention, the furan-functionalized side chain is directly connected to the central structural part and has the structure of formula (II):

[0019]

[0020] in

[0021] A is selected from -C 1-6 Alkyl-, -C 2-6 Alkenyl- and -C 1-6 Alkyl-O-; wherein the -C 1-6 Alkyl-, -C 2-6 Alkenyl- and -C 1-6 Each alkyl-O- is optionally and independently substituted by 1 to 3 groups selected from -halogen, -OH, -C 1-6 Alkyl, -C 1-6 Alkenyl and -OC 1-6 Substitution of alkyl groups;

[0022] B is selected from -C(O)O- and -O(O)C-;

[0023] k is an integer selected from the group consisting of: 0, 1, 2;

[0024] l is an integer selected from the group consisting of: 0, 1; and

[0025] m is an integer selected from the group consisting of 0, 1, 2, 3, 4, 5.

[0026] According to one embodiment of the present invention, the central structural moiety of formula (I) is directly attached to the prepolymer backbone.

[0027] According to one embodiment of the present invention, the central structural part of formula (I) is connected to the prepolymer main chain via a linker structure of formula (III):

[0028]

[0029] in

[0030] X is selected from -C 1-6 Alkyl- and -C 2-6 alkenyl-; wherein the -C 1-6 Alkyl- and -C 2-6 -alkenyl- are each optionally and independently substituted by 1 to 3 groups selected from -halogen, -OH, -C 1-6 Alkyl, -C 1-6 Alkenyl and -OC 1-6 Substitution of alkyl groups;

[0031] Y is selected from -C(O)O- and -O(O)C-;

[0032] Z is selected from -O- and -C(O)O-;

[0033] a is an integer selected from the group consisting of: 0, 1, 2; and

[0034] b is an integer selected from the group consisting of: 0, 1.

[0035] According to one embodiment of the present invention, the polymaleimide monomeric unit and the furan functionalized prepolymer both comprise a functionality of at least 2, and wherein the sum of the functionalities of both the polymaleimide monomeric unit and the furan functionalized prepolymer is at least 4.6.

[0036] According to one embodiment of the present invention, the stoichiometric ratio of maleimide to furan between the polymaleimide monomer units and the furan functionalized prepolymer is in the range of 1 to 0.25, preferably in the range of 1 to 0.6.

[0037] According to one embodiment of the present invention, the polymaleimide is selected from the list comprising the following compounds: 1,1'-(methylenebis-4,1-phenylene)bismaleimide, N,N'-(1,4-phenylene)bismaleimide, N,N'-(1,3-phenylene)bismaleimide, bismaleimide and the like.

[0038] According to another aspect, the present invention provides a composition comprising a Diels-Alder reaction based polymer as defined herein.

[0039] According to one embodiment of the present invention, the composition further comprises a free radical scavenger. According to a specific embodiment of the present invention, the free radical scavenger is selected from the list comprising the following compounds: hydroquinone, butylated hydroxytoluene, 4-tert-butylcatechol, methyl-p-benzoquinone, and the like.

[0040] According to another aspect, the present invention provides a process for the preparation of a polymer based on a Diels-Alder reaction as defined herein, the process comprising the step of preparing a composition comprising polymaleimide monomer units and a furan functionalized prepolymer.

[0041] According to another aspect, the present invention provides the use of a polymer or a composition based on a Diels-Alder reaction according to the invention.

[0042] According to another embodiment, the present invention provides the use of a polymer or composition based on the Diels-Alder reaction as a self-healing material.

[0043] According to another embodiment, the present invention provides the use of polymers or compositions based on the Diels-Alder reaction in robotics or biomedicine.

[0044] According to another embodiment, the present invention provides the use of a polymer or composition based on the Diels-Alder reaction in the manufacture of 1D, 2D or 3D structures, more particularly in the manufacture of robotic components.

[0045] According to another embodiment, the present invention provides the use of polymers or compositions based on the Diels-Alder reaction in filament extrusion, extrusion-based printing technology, laser selective sintering, injection molding, compression molding, casting, soft lithography, etc. According to a specific embodiment of the present invention, the extrusion-based printing technology is selected from the list comprising the following methods: molten filament manufacturing, direct writing technology, etc.

[0046] According to another aspect, the present invention provides a 1D, 2D or 3D structure comprising a polymer or composition based on a Diels-Alder reaction as defined herein.

[0047] BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Now with specific reference to the accompanying drawings, it should be emphasized that the details shown are only examples and are only used for the purpose of illustrative discussion of different embodiments of the present invention. The accompanying drawings are provided to provide what is believed to be the most useful and easiest description of the principles and concepts of the present invention. In this regard, no attempt is made to show the structural details of the present invention in more detail than is necessary for a basic understanding of the present invention. The description provided in conjunction with the accompanying drawings makes it clear to those skilled in the art how several forms of the present invention can be embodied in practice.

[0049] Figure 1 A chemical Diels-Alder reaction route between furan A and maleimide B groups to produce Diels-Alder reaction product C is shown according to one embodiment of the present invention.

[0050] Figure 2 Shown is a diagrammatic illustration of hydrogen bonding between different core moieties according to some embodiments of the present invention.

[0051] Figure 3 Castor oil (CO), maleated castor oil (mCO), and furan-functionalized maleated castor oil (FmCO) are shown. 1 H NMR spectroscopy.

[0052] Figure 4 The results of the analysis of succinate castor oil (sCO), itaconate castor oil (iCO), citrate castor oil (cCO) and maleate castor oil (mCO) are shown. 1 H NMR spectrum. Part of the itaconic anhydride is converted into citraconic anhydride during the reaction. Therefore, a peak corresponding to citraconicated castor oil may be found in the product of the reaction between itaconic anhydride and castor oil.

[0053] Figure 5 The results of furan-functionalized succinate castor oil (FsCO), furan-functionalized itaconate castor oil (FiCO), furan-functionalized citraconate castor oil (FcCO), and furan-functionalized maleate castor oil (FmCO) are shown. 1 H NMR spectroscopy.

[0054] Figure 6 Mechanical properties of intact materials are shown. Stress-strain curves for: a) three anhydride-based furan-functionalized materials (FmCO, FiCO, and FsCO) and DPBM, r = 1; b) furan-functionalized itaconated castor oil (FiCO) reacted with DPBM at different furan / maleimide molar ratios; and c) three anhydride-based furan-functionalized materials (FmCO, FiCO, and FsCO) and liquid bismaleimide BMI-689, r = 1.

[0055] Figure 7 Shown are a) dynamic rheological measurements of furan-functionalized maleated castor oil (FmCO) reacted with BMI-689 (r=1) from room temperature to 130°C; and b) DSC thermograms of furan-functionalized succinate castor oil (FsCO) reacted with 1,1′-(methylenedi-4,1-phenylene)bismaleimide (DPBM) at different furan / maleimide molar ratios.

[0056] Figure 8Shown are a) dynamic rheological measurement results at 50 to 130° C. and b) DSC thermogram of furan functionalized epoxidized soybean oil (FAcSO) reacted with BMI-689 according to Comparative Example A.

[0057] Fig. 9 Shown is the DSC thermogram of furan functionalized epoxidized soybean oil (sFASO) reacted with BMI-689 according to Comparative Example B.

[0058] Fig.10 The self-healing of FsCO-DPBM (r=0.8) over time is shown.

[0059] Fig.11 The mechanical properties and self-healing performance of the FmCO-DPBM (r = 0.8) material before and after reprocessing after three consecutive reprocessing cycles are shown. The values ​​of elongation or ultimate tensile stress are shown on the left, and the corresponding self-healing efficiency is shown on the right. DETAILED DESCRIPTION OF THE INVENTION

[0061] The present invention will now be further described. In the following paragraphs, different aspects of the present invention are defined in more detail. Unless clearly indicated to the contrary, each aspect so defined can be combined with any other one or more aspects. In particular, any feature that is indicated to be preferred or advantageous can be combined with any other one or more features that are indicated to be preferred or advantageous.

[0062] When describing the compounds of the present invention, the terms used are to be interpreted according to the following definitions, unless the context indicates otherwise:

[0063] The term "alkyl" by itself or as part of another substituent refers to a fully saturated, x H 2x or C x H 2x+1 wherein x is a number greater than or equal to 1. Typically, the alkyl groups of the present invention contain from 1 to 20 carbon atoms. The alkyl groups may be straight or branched and may be substituted as indicated herein. When a subscript is used after a carbon atom herein, the subscript refers to the number of carbon atoms that the designated group may contain. Thus, for example, C 1-4Alkyl refers to an alkyl group of 1 to 4 carbon atoms. Examples of alkyl groups are methyl, ethyl, n-propyl, isopropyl, butyl and isomers thereof (e.g., n-butyl, isobutyl and tert-butyl), pentyl and isomers thereof, hexyl and isomers thereof, heptyl and isomers thereof, octyl and isomers thereof, nonyl and isomers thereof, decyl and isomers thereof. C1-C6 alkyl includes all straight, branched or cyclic alkyl groups with 1 to 6 carbon atoms, thus including methyl, ethyl, n-propyl, isopropyl, butyl and isomers thereof (e.g., n-butyl, isobutyl and tert-butyl), pentyl and isomers thereof, hexyl and isomers thereof, cyclopentyl, 2-, 3- or 4-methylcyclopentyl, cyclopentylmethyl, and cyclohexyl. Optionally substituted alkyl refers to an alkyl group optionally having one or more (e.g., 1, 2, 3 or 4 substituents) substituents.

[0064] The term "alkenyl" by itself or as part of another substituent refers to a straight chain, cyclic, or branched hydrocarbon group containing at least one carbon-carbon double bond. Thus, for example, C 2-4 Alkenyl refers to an alkenyl group of 2 to 4 carbon atoms. Examples of alkenyl groups include 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-hexadienyl, E, Z-hexadienyl, Z, E-hexadienyl, Z, Z-hexadienyl, etc. Optionally substituted alkenyl refers to an alkenyl group optionally having one or more (e.g., 1, 2, 3 or 4) substituents. C1 alkenyl refers to a vinyl moiety, wherein the C1 substituent forms a carbon-carbon double bond together with the carbon to which the substituent is connected.

[0065] Whenever used in the present invention, the term "compounds of the present invention" or similar terms are intended to include compounds of Formula I and any subgroups thereof. The term also refers to their derivatives, such as solvates, hydrates, stereoisomeric forms, racemic mixtures, tautomeric forms and optical isomers.

[0066] As used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. For example, "a compound" refers to one compound or more than one compound. The above terms and other terms used in the specification are fully understood by those skilled in the art. The compounds of the present invention can be prepared according to the reaction routes provided in the examples below, but those skilled in the art will understand that these are merely illustrative of the present invention, and the compounds of the present invention can be prepared by any of several standard synthetic methods commonly used by those skilled in the art of organic chemistry.

[0067] According to a first aspect, the present invention provides a polymer based on a Diels-Alder reaction comprising the reaction product of a polymaleimide monomer unit and a furan-functionalized prepolymer; wherein the furan-functionalized prepolymer is characterized by having a prepolymer backbone comprising substituents having a central moiety of formula (I):

[0068]

[0069] Where R 1 is -H; wherein at least one furan-functionalized side chain is attached to the central moiety; and wherein the prepolymer backbone is polyester-based.

[0070] When referred to herein, unless otherwise specified, the term "Diels-Alder reaction-based polymer" is understood to be a polymer network containing reversible covalent crosslinks, which is formed by the Diels-Alder reaction between furan and maleimide, which produces either isomer of the cycloadduct known as a "Diels-Alder bond". The network structure is formed using two reactive structural parts, namely a furan-functionalized prepolymer and a multimaleimide, particularly a bismaleimide. The Diels-Alder reaction to form the Diels-Alder bond is an equilibrium reaction, so that the crosslinked bonds formed are dynamic. In the dynamic network, bonds are constantly broken and re-formed over time. However, as long as the temperature remains unchanged, the crosslink density can be defined for that specific temperature.

[0071] If the Diels-Alder network is damaged, the Diels-Alder bonds and hydrogen bonding interactions are locally broken in a reversible manner, thereby generating an active fracture surface. Hydrogen donors and acceptors, as well as newly formed furan and maleimide functionalities due to the reversible mechanical breakage of the Diels-Alder bonds, autonomously reform the broken bonds, thereby restoring the polymer network structure and associated properties. The repair process is synergistically accelerated by the presence of hydrogen bonds near the Diels-Alder bonds. In order to achieve repair of this damaged area, the first part of the self-healing process is to bring the fracture surfaces back into contact. Depending on the size of the damage, manual intervention or robotic system intervention may be required to actively push the two fracture surfaces back together, such as when the material is completely cut and forms two separate parts. Such a complete cut requires pushing the two broken parts back together to initiate the repair process. In this case, it is important to push the two parts back together as soon as possible after the damage occurs.

[0072] The fractured surfaces are brought back into contact as soon as possible, preferably within 1 to 2 hours after the damage occurs. Otherwise, the available reactive groups (maleimide and furan) will react with each other in the separated parts, resulting in a reduction in the repair rate and efficiency under given repair conditions. Nevertheless, parts separated for a longer time can still be efficiently repaired if the repair time is greatly increased or if the temperature is increased.

[0073] After the broken surfaces come back together (autonomously or non-autonomously), the self-healing process begins. At this point, there is a risk of microscopic dislocations and small cavities between the broken surfaces. This is a synergistic combination of the weak hydrogen bonding interaction and the dynamic Diels-Alder covalent bonding of the present invention ( Figure 1 and Figure 2 ) play an important role. On the one hand, when the material is damaged, weak hydrogen bonds help to immediately restore some of the mechanical properties, ensuring good contact and immediate adhesion when the broken surfaces come into contact again. On the other hand, Diels-Alder bonds are the main contributors to the mechanical properties and prevent or reduce creep.

[0074] The specific structure of the central moiety is key to the self-healing properties of the present invention, providing both a hydrogen acceptor (carbonyl) as well as a hydrogen donor (hydroxyl).

[0075] Due to the reversibility of Diels-Alder bonds and hydrogen bonds, the polymer network structure can be reversibly polymerized and depolymerized, and thus the material can be thermally processed, manufactured, and recycled using common thermal and chemical processing methods.

[0076] Unless otherwise specified, the term "self-repair efficiency" used herein should be understood as the recovery of material properties (e.g., mechanical strength) and is measured by the ratio of the properties measured after repair to the initial material properties (i.e., the properties before damage). The repair efficiency is based on, for example, mechanical modulus, mechanical strength characterized by fracture stress and fracture strain. The efficiency can be expressed as a percentage.

[0077] Unless otherwise specified, the concept of "autonomous self-repair" used in this article should be understood as the ability of self-healing materials (such as polymers based on Diels-Alder reactions) to be repaired without any external intervention of any type (such as without the need for elevated temperature) once the broken surfaces are brought into contact with each other upon damage.

[0078] According to some embodiments of the invention, self-healing occurs at a temperature below 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 5°C.

[0079] According to some embodiments of the present invention, self-healing can occur at a temperature between about 10, 15, 20° C. and 30, 40, 50° C., and in particular at a temperature between about 15, 20, 25° C. and 30, 35, 40° C. According to some embodiments of the present invention, an increase in temperature can improve the self-healing efficiency, but it is still a feature of the polymers based on the Diels-Alder reaction of the present invention that the self-healing process can occur at these lower ambient temperatures.

[0080] According to some embodiments of the present invention, a self-repair efficiency of about 80%, about 90%, or about 100%, in particular about 90%, about 95%, or about 99%, can be achieved at room temperature. After about 1 to 2 days at about 25°C, a self-repair efficiency of about 70%, about 80% has been achieved. After about 7 days at about 25°C, a self-repair efficiency of about 96%, about 97%, or about 98% has been achieved. It should be noted that a 100% repair efficiency means that all mechanical and fracture properties of the material have been restored, and the properties required for the application can be restored in a much shorter time.

[0081] One advantage of the present invention is that the Diels-Alder reaction based polymers contain both the necessary chain mobility in the network and sufficient concentration of reactive components (Diels-Alder bonds and hydrogen bonds) to repair macroscopic damage at a fairly fast rate and high repair efficiency at room temperature.

[0082] According to some embodiments of the present invention, the repair time can be in the range of from a few minutes to a few hours to a few days, more specifically in the range of from about 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60 minutes to about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30 days. In addition to temperature, the time of self-repair also affects the repair efficiency. The longer the time that the damaged material is allowed to self-repair (i.e., keep the fracture surface in good contact), the higher the repair efficiency at a given temperature. Among other things, aspects such as the ratio of maleimide to furan, available reactive groups, the flexibility of monomer units, cross-linking density, molecular mobility, repair temperature, and the time between fracture and fracture surface contact can affect the repair time required to achieve a certain repair efficiency. According to some embodiments of the present invention, the repair time can be reduced by increasing the repair temperature. However, an advantage of embodiments of the present invention is that repair can occur at room temperature and even below room temperature.

[0083] According to some embodiments of the present invention, the damaged surface of the polymer based on the Diels-Alder reaction can be fully restored because the initial strength of the polymer based on the Diels-Alder reaction is fully regained. Referring to the examples below, it was found that such full recovery in which the initial strength of the polymer based on the Diels-Alder reaction is fully regained occurs particularly when the fracture surfaces are realigned when the fracture surfaces are in contact with each other.

[0084] The prepolymer backbone of the furan functionalized prepolymer can be based on any suitable polyester. Examples of such suitable polyesters are naturally occurring fatty acid esters or condensation products of fatty acids or mixtures thereof with aliphatic polyols. The polyol can be, for example, selected from 1,2-ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol and dipentaerythritol. The fatty acid can be, for example, selected from unsaturated fatty acids such as oleic acid, linoleic acid and linolenic acid, or hydroxy fatty acids such as 12-hydroxystearic acid, 12-hydroxyoctadec-9-enoic acid and 14-hydroxyeicosyl-11-enoic acid. Other examples of suitable polyesters are condensation products of aliphatic or aromatic polyols with aliphatic or aromatic polycarboxylic acids, condensation products of hydroxy fatty acids, or polyesters obtained by other polymerization means such as, but not limited to, ring-opening polymerization of lactones.

[0085] According to one embodiment of the present invention, the furan-functionalized side chain is directly connected to the central structural part and has the structure of formula (II):

[0086]

[0087] in

[0088] A is selected from -C 1-6 Alkyl-, -C 2-6 Alkenyl- and -C 1-6 Alkyl-O-; wherein the -C 1-6 Alkyl-, -C 2-6 Alkenyl- and -C 1-6 Each alkyl-O- is optionally and independently substituted by 1 to 3 groups selected from -halogen, -OH, -C 1-6 Alkyl, -C 1-6 Alkenyl and -OC 1-6 Substitution of alkyl groups;

[0089] B is selected from -C(O)O- and -O(O)C-;

[0090] k is an integer selected from the group consisting of: 0, 1, 2;

[0091] l is an integer selected from the group consisting of: 0, 1; and

[0092] m is an integer selected from the group consisting of 0, 1, 2, 3, 4, 5.

[0093] According to one embodiment of the present invention, the central structural moiety of formula (I) is directly attached to the prepolymer backbone.

[0094] According to one embodiment of the present invention, the central structural part of formula (I) is connected to the prepolymer main chain via a linker structure of formula (III):

[0095]

[0096] in

[0097] X is selected from -C 1-6 Alkyl- and -C 2-6 alkenyl-; wherein the -C 1-6 Alkyl- and -C 2-6 -alkenyl- are each optionally and independently substituted by 1 to 3 groups selected from -halogen, -OH, -C 1-6 Alkyl, -C 1-6 Alkenyl and -OC 1-6 Substitution of alkyl groups;

[0098] Y is selected from -C(O)O- and -O(O)C-;

[0099] Z is selected from -O- and -C(O)O-;

[0100] a is an integer selected from the group consisting of: 0, 1, 2; and

[0101] b is an integer selected from the group consisting of: 0, 1.

[0102] According to one embodiment of the present invention, there is provided a polymer based on a Diels-Alder reaction, comprising the reaction product of a polymaleimide monomer unit and a furan-functionalized prepolymer;

[0103] wherein the furan-functionalized prepolymer is characterized by having a prepolymer backbone comprising substituents having a central moiety of formula (I);

[0104]

[0105] Where R 1 is -H; wherein at least one furan-functionalized side chain is directly attached to the central moiety; and wherein the prepolymer backbone is polyester-based;

[0106] wherein at least one furan-functionalized side chain of formula (II) is directly attached to the central structural portion of formula (I);

[0107]

[0108] in

[0109] A is selected from -C 1-6 Alkyl-, -C 2-6 Alkenyl- and -C 1-6 Alkyl-O-; wherein the -C 1-6 Alkyl-, -C 2-6 Alkenyl- and -C 1-6 Each alkyl-O- is optionally and independently substituted by 1 to 3 groups selected from -halogen, -OH, -C 1-6 Alkyl, -C 1-6 Alkenyl and -OC 1-6 Substitution of alkyl groups;

[0110] B is selected from -C(O)O- and -O(O)C-;

[0111] k is an integer selected from the group consisting of: 0, 1, 2;

[0112] l is an integer selected from the group consisting of: 0, 1; and

[0113] m is an integer selected from the group consisting of 0, 1, 2, 3, 4, 5.

[0114] According to another specific embodiment of the present invention, there is provided a Diels-Alder reaction based polymer comprising the reaction product of a polymaleimide monomer unit and a furan functionalized prepolymer;

[0115] wherein the furan-functionalized prepolymer is characterized by having a prepolymer backbone comprising substituents having a central moiety of formula (I);

[0116]

[0117] Where R 1 is -H; wherein at least one furan-functionalized side chain is attached to the central moiety; and wherein the prepolymer backbone is polyester-based;

[0118] wherein at least one furan-functionalized side chain of formula (II) is directly attached to the central structural moiety;

[0119]

[0120] in

[0121] A is selected from -C 1-6 Alkyl-, -C 2-6 Alkenyl- and -C 1-6 Alkyl-O-; wherein the -C1-6 Alkyl-, -C 2-6 Alkenyl- and -C 1-6 Each alkyl-O- is optionally and independently substituted by 1 to 3 groups selected from -halogen, -OH, -C 1-6 Alkyl, -C 1-6 Alkenyl and -OC 1-6 Substitution of alkyl groups;

[0122] B is selected from -C(O)O- and -O(O)C-;

[0123] k is an integer selected from the group consisting of: 0, 1, 2;

[0124] l is an integer selected from the group consisting of: 0, 1; and

[0125] m is an integer selected from the group consisting of: 0, 1, 2, 3, 4, 5; and

[0126] in

[0127] The central structure part is connected to the prepolymer main chain through a linker structure of formula (III):

[0128]

[0129] in

[0130] X is selected from -C 1-6 Alkyl- and -C 2-6 alkenyl-; wherein the -C 1-6 Alkyl- and -C 2-6 -alkenyl- are each optionally and independently substituted by 1 to 3 groups selected from -halogen, -OH, -C 1-6 Alkyl, -C 1-6 Alkenyl and -OC 1-6 Substitution of alkyl groups;

[0131] Y is selected from -C(O)O- and -O(O)C-;

[0132] Z is selected from -O- and -C(O)O-;

[0133] a is an integer selected from the group consisting of: 0, 1, 2; and

[0134] b is an integer selected from the group consisting of: 0, 1.

[0135] Scheme 1 provides a reaction route for preparing a polymer based on the Diels-Alder reaction according to a specific embodiment of the present invention, which starts from castor oil (CO) and itaconic anhydride (IA), further reacts with furanyl glycidyl ether (FGE), and finally crosslinks with DPBM.

[0136]

[0137] According to one embodiment of the present invention, the polymaleimide monomeric unit and the furan functionalized prepolymer both comprise a functionality of at least 2, and wherein the sum of the functionalities of both the polymaleimide monomeric unit and the furan functionalized prepolymer is at least 4.6.

[0138] Unless otherwise specified, functionality is understood to be the number of maleimide groups or furan groups on the polymaleimide monomer units and the furan-functionalized prepolymer, respectively.

[0139] According to one embodiment of the present invention, the stoichiometric ratio of maleimide to furan between the polymaleimide monomer units and the furan functionalized prepolymer is in the range of 1 to 0.25, preferably in the range of 1 to 0.6.

[0140] Unless otherwise specified, the maleimide to furan stoichiometric ratio (r) is understood to be the molar ratio of maleimide groups to furan groups.

[0141] According to one embodiment of the present invention, the polymaleimide is selected from a list comprising the following compounds: 1,1'-(methylenebis-4,1-phenylene)bismaleimide (DPBM), N,N'-(1,4-phenylene)dimaleimide, N,N'-(1,3-phenylene)dimaleimide, bismaleimide, Homide 122G, Homide 116, BMI-689, BMI-1400, BMI-1700, etc.

[0142] According to another aspect, the present invention provides a composition comprising a Diels-Alder reaction based polymer as defined herein.

[0143] According to some embodiments of the present invention, the composition further comprises a free radical scavenger. According to a specific embodiment of the present invention, the free radical scavenger is selected from a list comprising the following compounds: hydroquinone, butylated hydroxytoluene, 4-tert-butylcatechol, methyl-p-benzoquinone, etc. According to some embodiments of the present invention, the composition may further comprise an additive, which adds a function or characteristic to the reaction product, such as color, texture, tactile experience, flexibility, processability, viscosity at high temperature, electrical or magnetic properties, etc.

[0144] According to another aspect, the present invention provides a process for the preparation of a polymer based on a Diels-Alder reaction as defined herein, the process comprising the step of preparing a composition comprising polymaleimide monomer units and a furan functionalized prepolymer.

[0145] According to another aspect, the present invention provides the use of a polymer or a composition based on a Diels-Alder reaction according to the invention.

[0146] According to another embodiment, the present invention provides the use of a polymer or composition based on the Diels-Alder reaction as a self-healing material.

[0147] According to another embodiment, the present invention provides the use of polymers or compositions based on the Diels-Alder reaction in robotics or biomedicine.

[0148] According to some embodiments of the present invention, the use in robotics may constitute a subfield of soft robotics. Unless otherwise specified, the term "soft robotics" as used herein should be understood as a subfield of robotics covering the construction of robotic parts and robots from different types of materials with properties close to those found in biological organisms. These materials often require a certain degree of flexibility and adaptability, depending on their specific use.

[0149] As mentioned before, an example of a robotic system is a soft robotic system such as the fabrication of soft grippers that can be used in agriculture, such as for picking fruit. In these cases, the material of these soft grippers should allow the handling of delicate fruit (e.g. strawberries) without damaging the fruit. However, in these cases, damage to these soft grippers is inevitable, such as by sharp branches and thorns. This is just one example of how the special properties of self-healing, Diels-Alder reaction-based polymers provide great advantages when applied in the field of robotics.

[0150] According to some embodiments of the present invention, the soft robotic actuator may include a plurality of bent soft pneumatic actuators (BSPAs). These BSPAs together may be more specifically used as finger-like structures of the soft robotic system, such as a soft gripper. Its bendability allows the finger-like structures to mimic the motion of humanoid gestures.

[0151] According to another embodiment, the present invention provides the use of a polymer or composition based on the Diels-Alder reaction for the manufacture of 1D, 2D or 3D structures, more particularly for the manufacture of robotic components.

[0152] According to another embodiment, the present invention provides the use of polymers or compositions based on the Diels-Alder reaction in filament extrusion, extrusion-based printing technology, laser selective sintering, injection molding, compression molding, casting, soft lithography, etc. According to a specific embodiment of the present invention, the extrusion-based printing technology is selected from the list comprising the following methods: molten filament manufacturing, direct writing technology, etc.

[0153] According to another aspect, the present invention provides a 1D, 2D or 3D structure comprising a Diels-Alder reaction based polymer or composition as defined herein.

[0154] The compounds of the present invention can be prepared according to the methods provided in the examples below, but those skilled in the art will appreciate that these methods are only used to illustrate the present invention, and the compounds of the present invention can be prepared by any of several standard synthetic methods commonly used by those skilled in the art of organic chemistry.

[0155] As mentioned above, the self-healing property of the Diels-Alder polymer is based on the reversible cross-linking reaction between the furan-functionalized prepolymer of formula (I) and the polymaleimide. Figure 1 A reversible Diels-Alder reaction route between furan A and maleimide B groups to produce Diels-Alder reaction product C is shown. The reversible Diels-Alder polymer network is based on a reversible Diels-Alder reaction between functionalized furan A and maleimide groups B to produce strong covalent bonds that can be broken by thermal or mechanical means and reversibly reformed, thereby achieving the self-healing property. Example

[0156] Material

[0157] Succinic anhydride (SA), itaconic anhydride (IA), maleic anhydride (MA), castor oil (CO; 164 mg KOH / g), furancarbinol (FA), 3-furancarboxylic acid (FAc), and 1,1'-(methylenedi-4,1-phenylene)bismaleimide (DPBM) were obtained from Sigma Aldrich. 4-tert-Butylcatechol was used as a free radical inhibitor and was obtained from Sigma Aldrich. Furanmethyl glycidyl ether (FGE) was obtained from Sage Chemicals (Hangzhou, China). Epoxidized soybean oil (SO) was obtained from Varteco (Santa Fe, Argentina). BMI-689 was obtained from Designer Molecules (Willow Creek, San Diego). All products were used as received.

[0158] analyze

[0159] 1 H NMR was performed on a Bruker Avance DRX 250 with an opening frequency of 250 MHz. The analysis was performed at room temperature using CDCl3 as solvent and TMS as internal standard. The concentration of the measured sample was 10 mg m -1 .

[0160] Fourier transform infrared (FTIR) spectroscopy was performed at ambient temperature using a Nicolet 6700 FTIR spectrometer from Thermo Scientific using OMNIC as the software package. All spectra were acquired at 4000 cm -1 Up to 600cm -1 The average is obtained from 32 scans recorded within the scope.

[0161] GPC analysis was performed on a Shimadzu system using a combination of Styragel HR0.5 and HR1 columns connected to RID and UV detectors. The instrument was calibrated with polystyrene internal standards and eluted with tetrahydrofuran (THF).

[0162] Differential scanning calorimetry (DSC) was performed on a TA Instruments Discovery DSC equipped with a refrigerated cooling system (RCS). All experiments were performed in Tzero aluminum pans under sealed conditions, using nitrogen as the purge gas, and a heating / cooling rate of 5 °C min -1 .

[0163] Dynamic mechanical analysis (DMA) was performed on a TA Instruments DMA Q800 equipped with a nitrogen 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 at 60% min. -1 The strain rate was 2 °C min-1. The Young's modulus was determined in the initial linear region (0-1% strain) of the stress-strain curve. To study the viscoelastic properties, the strain rate was 2 °C min-1 at -80 °C and 90 °C. -1 The samples were measured with small amplitude oscillations at a frequency of 1 Hz and a strain of 0.1% during a heating-cooling cycle at a rate of 1 Hz.

[0164] Dynamic rheological measurements were performed using a TA instrument Discovery Hybrid Rheometer (DHR2). The samples were cut into circular shapes and placed between 10 mm diameter aluminum parallel plates. The samples were subjected to 5% oscillatory strain at different frequencies: 0.312, 0.562, 1.0, 1.778 and 3.125 Hz. At the same time, the temperature was varied between 40°C and 120°C to determine the gel transition temperature.

[0165] For accelerated in vitro degradation testing, three squares of 10 mm x 10 mm x 1.25 mm were cut out for each sample and placed in a KCl NaOH buffer solution at pH 13 and 37°C for 14 days. The samples were dried and weighed every day, and the mass loss was measured.

[0166] synthesis

[0167] Example 1

[0168] Castor oil was subjected to a ring-opening esterification reaction using maleic anhydride (MA). The reaction was carried out under N2 atmosphere, without solvent and with magnetic stirring. A 1:1 molar ratio between the hydroxyl groups in castor oil and the anhydride was used. The esterification reaction was carried out at 100°C for 24 hours. The obtained maleated castor oil (mCO) was used without any further purification.

[0169] Example 2

[0170] Castor oil was subjected to a ring-opening esterification reaction using itaconic anhydride (IA). The reaction was carried out under N2 atmosphere, without solvent and with magnetic stirring. A 1:1 molar ratio between the hydroxyl groups in castor oil and the anhydride was used. The esterification reaction was carried out at 100°C for 24 hours. The obtained itaconic castor oil (iCO) was used without any further purification.

[0171] Example 3

[0172] Castor oil was subjected to a ring-opening esterification reaction using succinic anhydride (SA). The reaction was carried out under N2 atmosphere, without solvent and with magnetic stirring. A molar ratio of 1:1 between the hydroxyl groups in castor oil and the anhydride was adopted. The esterification reaction was carried out at 130°C for 24 hours. The obtained succinic castor oil (sCO) was used without any further purification.

[0173] Example 4

[0174] Furan methyl glycidyl ether (FGE) was directly mixed with mCO in a 1:1 molar ratio with anhydride. The reaction was carried out under N2 atmosphere, without solvent and with magnetic stirring. The functionalization reaction was completed at 120°C overnight. The obtained furan functionalized maleated castor oil (FmCO) was used in the subsequent steps without any further purification.

[0175] Example 5

[0176] Furanyl methyl glycidyl ether (FGE) was directly mixed with iCO in a 1:1 molar ratio with anhydride. The reaction was carried out under N2 atmosphere, without solvent and with magnetic stirring. The functionalization reaction was completed at 120°C overnight. The obtained furan functionalized itaconated castor oil (FiCO) was used in the subsequent steps without any further purification.

[0177] Example 6

[0178] Furan methyl glycidyl ether (FGE) was directly mixed with sCO in a 1:1 molar ratio with anhydride. The reaction was carried out under N2 atmosphere, without solvent and with magnetic stirring. The functionalization reaction was completed at 120°C overnight. The obtained furan functionalized succinate castor oil (FsCO) was used in the subsequent steps without any further purification.

[0179] Example 7

[0180] FmCO, FiCO, and FsCO were cross-linked using two different bismaleimides, 1,1′-(methylenebis-4,1-phenylene)bismaleimide (DPBM) and a commercial low-viscosity bismaleimide (BMI-689) derived from fatty acids.

[0181] To prepare the network crosslinked with DPBM, the functionalized castor oil sample was placed in a separate beaker and DPBM was added to the mixture, preparing 3 different molar ratios between furan and maleimide groups for each functionalized oil (1:1, 1:0.8, 1:0.6). Finally, 1 wt% of 4-tert-butylcatechol was added to prevent free radical side reactions between maleimide groups. The mixture was heated until the DPBM melted and formed a homogeneous solution with the functionalized oil. Subsequently, the homogeneous solution was poured into a square PTFE mold. The sample was demoulded after 2 hours and the final mechanical properties of the material were obtained after curing at room temperature for 24 hours.

[0182] Samples cross-linked with BMI-689 were prepared by briefly mixing the functionalized oil with BMI-689 at room temperature for at least 24 hours.

[0183] Comparative Example A

[0184] 3-Furancarboxylic acid was directly mixed with epoxidized soybean oil in a 1:1 molar ratio of epoxide rings in epoxidized soybean oil. The reaction was carried out under N2 atmosphere, without solvent and with magnetic stirring. The functionalization reaction was completed at 120°C overnight. The obtained furan functionalized epoxidized soybean oil (FAcSO) was used in the subsequent steps without any further purification.

[0185] The furan functionalized epoxidized soybean oil (FAcSO) was mixed with BMI-689 bismaleimide in a ratio of 70 wt.% of the furan functionalized epoxidized soybean oil and 30 wt.% of BMI-689. The mixture was allowed to react at room temperature for two days. After the reaction, the mixture became a solid elastic material.

[0186] Comparative Example B

[0187] Furan alcohol (FA) was mixed with succinic anhydride (SA) at a molar ratio of 1:1 to anhydride. The reaction was carried out at 50° C. overnight under ambient conditions. The obtained succinylated furan alcohol (sFA) was used in the subsequent step without any further purification.

[0188] Succinate furan alcohol (sFA) was mixed with epoxidized soybean oil in a 1:1 ratio of epoxy rings in epoxidized soybean oil. The mixture was reacted at 120° C. overnight under N2 atmosphere without solvent and magnetic stirring. The obtained furan functionalized epoxidized soybean oil (sFASO) was used in the subsequent step without any further purification.

[0189] The resulting furan functionalized epoxidized soybean oil (sFASO) was crosslinked using two different bismaleimides, 1,1′-(methylenebis-4,1-phenylene)bismaleimide (DPBM) and (BMI-689) bismaleimide.

[0190] To prepare a network crosslinked with DPBM, sFASO was mixed with DPBM in a molar ratio of 1: 1 between furan and maleimide groups. The mixture was reacted at 150° C. with stirring and then poured into a mold. After cooling, the material became an elastic solid.

[0191] To prepare a network crosslinked with BMI-689, the sFASO was mixed with the bismaleimide in a ratio of 70 wt.% furan functionalized epoxidized soybean oil and 30 wt.% BMI-689. The mixture was allowed to react at room temperature for two days. After the reaction, the mixture became a solid elastic material.

[0192] Mechanical properties and self-healing efficiency

[0193] A comparison of the mechanical properties and self-healing efficiency of twelve different materials prepared in Example 7 is shown in Table 1. The materials were synthesized using three different cyclic anhydrides (maleic anhydride, itaconic anhydride, and succinic anhydride) crosslinked with two different bismaleimides (DPBM and BMI-689) at three different furan / maleimide stoichiometric ratios.

[0194]

[0195] Preparation of soft robotic gripper

[0196] The soft robotic gripper was prepared by casting a mold of the self-healing material. The mold was obtained by 3D printing using a Prusa SL1 Stereolithography (SLA) printer and 3DM-HTR140 resin. The gripper consists of 8 different parts, which were connected together using a soldering iron at 150°C to apply localized heat at the joints.

Claims

1. A polymer based on a Diels-Alder reaction comprising the reaction product of a polymaleimide monomer unit and a furan-functionalized prepolymer; The furan-functionalized prepolymer is characterized by having a prepolymer backbone comprising substituents having a central moiety of formula (I): Where R 1 is -H; wherein at least one furan-functionalized side chain is attached to the central moiety; and wherein the prepolymer backbone is polyester-based.

2. The Diels-Alder reaction-based polymer of claim 1, wherein the furan-functionalized side chains are directly attached to the central structural moiety and have a structure of formula (II): in A is selected from -C 1-6 Alkyl-, -C 2-6 Alkenyl- and -C 1-6 Alkyl-O-; wherein the -C 1-6 Alkyl-, -C 2-6 Alkenyl- and -C 1-6 Each alkyl-O- is optionally and independently substituted by 1 to 3 groups selected from -halogen, -OH, -C 1-6 Alkyl, -C 1-6 Alkenyl and -OC 1-6 Substitution of alkyl groups; B is selected from -C(O)O- and -O(O)C-; k is an integer selected from the group consisting of: 0, 1, 2; l is an integer selected from the group consisting of: 0, 1; and m is an integer selected from the group consisting of 0, 1, 2, 3, 4, 5.

3. The Diels-Alder reaction-based polymer of any one of claims 1-2, wherein the central structural part of formula (I) is directly attached to the prepolymer backbone.

4. The Diels-Alder reaction-based polymer of claim 3, wherein the central structural moiety of formula (I) is connected to the prepolymer backbone via a linker structure of formula (III): in X is selected from -C 1-6 Alkyl- and -C 2-6 alkenyl-; wherein the -C 1-6 Alkyl- and -C 2-6 -alkenyl- are each optionally and independently substituted by 1 to 3 groups selected from -halogen, -OH, -C 1-6 Alkyl, -C 1-6 Alkenyl and -OC 1-6 Substitution of alkyl groups; Y is selected from -C(O)O- and -O(O)C-; Z is selected from -O- and -C(O)O-; a is an integer selected from the group consisting of: 0, 1, 2; and b is an integer selected from the group consisting of: 0, 1.

5. The Diels-Alder reaction-based polymer of any one of claims 1-4, wherein the multimaleimide monomer unit and the furan-functionalized prepolymer both comprise a functionality of at least 2, and wherein the sum of the functionalities of the multimaleimide monomer unit and the furan-functionalized prepolymer is at least 4.

6.

6. The Diels-Alder reaction based polymer of any one of claims 1 to 4, wherein the stoichiometric ratio of maleimide to furan between the polymaleimide monomer units and the furan functionalized prepolymer is in the range of 1 to 0.

25.

7. The Diels-Alder reaction based polymer of any one of claims 1 to 4, wherein the stoichiometric ratio of maleimide to furan between the multi-maleimide monomer units and the furan functionalized prepolymer is in the range of 1 to 0.

6.

8. The Diels-Alder reaction-based polymer of any one of claims 1 to 7, wherein the polymaleimide is selected from the list comprising 1,1'-(methylenebis-4,1-phenylene)bismaleimide, N,N'-(1,4-phenylene)bismaleimide, N,N'-(1,3-phenylene)bismaleimide and bismaleimide.

9. A composition comprising a polymer as defined in any one of claims 1 to 8.

10. The composition of claim 9, further comprising a free radical scavenger.

11. The composition of claim 10, wherein the free radical scavenger is selected from the list comprising hydroquinone, butylated hydroxytoluene, 4-tert-butylcatechol, methyl-p-benzoquinone.

12. A process for the preparation of a polymer based on a Diels-Alder reaction as defined in any one of claims 1 to 4, comprising the step of preparing a composition comprising polymaleimide monomer units and a furan functionalized prepolymer.

13. Use of a polymer based on the Diels-Alder reaction as defined in any one of claims 1 to 8 or a composition as defined in claims 9 to 11 as a self-healing material.

14. Use of a polymer based on the Diels-Alder reaction as defined in any one of claims 1 to 8 or a composition as defined in claims 9 to 11 in robotics or biomedicine.

15. Use of a polymer based on the Diels-Alder reaction as defined in any one of claims 1 to 8 or a composition as defined in claims 9 to 11 for the manufacture of 1D, 2D or 3D structures.

16. Use of a polymer based on the Diels-Alder reaction as defined in any one of claims 1 to 8 or a composition as defined in claims 9 to 11 for the manufacture of a robotic component.

17. Use of a polymer based on the Diels-Alder reaction as defined in any one of claims 1 to 8 or a composition as defined in claims 9 to 11 in a manufacturing process selected from the list comprising the following methods: filament extrusion, extrusion-based printing technology, laser selective sintering, injection molding, compression molding, casting, soft lithography.

18. The use as defined in claim 17, wherein the extrusion-based printing technology is selected from the list comprising: fused filament fabrication, direct writing technology.

19. A 1D, 2D or 3D structure comprising a polymer based on a Diels-Alder reaction as defined in any one of claims 1 to 8 or a composition as defined in claims 9 to 11.

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