Self-repairing polymers and formulations for preparing self-repairing polymers

Abstract

A thermally stable, self-repairing, two-capsule system is described that can withstand high temperatures during FROMP while maintaining vitality for an extended period of time before its payload is released during a repair event. In particular, a two-capsule system comprising monomeric microcapsules and catalyst microcapsules has been used to prove that self-repair of p (DCPD) with low catalyst loading achieves high repair efficacy and mechanical strength.

Description

Cross-reference to related applications

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 454,806, filed March 27, 2023, the entire contents of which are incorporated herein by reference for all purposes. Statement on Federally Funded Research

[0002] This invention was made with government support from a grant of DE-AR0001330 from the U.S. Department of Energy. The government holds certain rights to this invention. Background Technology

[0003] Frontal polymerization (FP) is an energy-efficient technology that involves an initial energy stimulus that causes monomer resins to fully cure via self-propagation at a steady-state frontal velocity. At the polymerization front, low-viscosity monomers rapidly transform into cross-linked networks, thus forming a well-defined monomer-polymer interface.

[0004] As an example of FP, frontier ring-opening metathesis polymerization (FROMP) of dicyclopentadiene (DCPD) catalyzed by Grubbs-type ruthenium complexes has demonstrated compatibility with a wide range of applications, from additive manufacturing technologies (e.g., 3D printing) to composite material fabrication.

[0005] Poly(dicyclopentadiene) (p(DCPD)) materials have ideal properties, and their thermochemical stability is comparable to or even better than that of ordinary bisphenol A (BPA) epoxy resins suitable for conventional manufacturing methods. However, p(DCPD) materials may be damaged during their service life due to a variety of factors such as thermal stress, continuous or high cyclic fatigue loads, underwater conditions, high pressure or corrosive environments.

[0006] Fail-safe features, such as self-healing, can extend the service life of thermoset materials by repairing minor damage or small fatigue cracks, thus delaying their propagation to more catastrophic areas. Autonomous self-healing offers a cost-effective solution for extending the service life of materials in hard-to-access areas, such as spacecraft or buried pipelines, where repair or replacement is expensive. However, currently, there are virtually no strategies for non-invasively repairing engineered materials damaged by extreme environments such as space, near-shore waters, and high-pressure applications.

[0007] Previous studies have focused on the self-healing of epoxy resins and epoxy vinyl ester thermosetting plastics and their composites using various generations and derivatives of microencapsulated (or microvascularized) DCPD and Grubbs catalysts (e.g., [(SIMes)Ru(=CHPh)(PCy3)Cl2]; G2). However, the same effect cannot be achieved for p(DCPD) matrices utilizing G2 or wax-coated catalyst particles due to their thermal and chemical instability during high-temperature manufacturing (e.g., FROMP). Furthermore, limitations such as poor control over solid catalyst size, inefficient mixing of the repair agent, and wax plasticization of the repair layer necessitate an excess of catalyst (2.5 wt.%) to achieve satisfactory repair efficiency and a peak load of 50 N, as measured in a tapered double cantilever beam (TDCB) test. Summary of the Invention

[0008] This paper describes a thermally stable self-healing dual-capsule system that can withstand high temperatures during FROMP while maintaining its activity for an extended period before releasing its payload during the healing event. Specifically, dual-capsule systems comprising monomeric microcapsules and catalyst microcapsules have been used to demonstrate that self-healing with low catalyst loading on p(DCPD) achieves high healing efficacy and mechanical strength.

[0009] The thermally stable catalyst was used in dissolved form (e.g., about 1 wt.%), ensuring homogeneous mixing of the two-component remediation system and allowing for adjustment of the stoichiometry of the remediation agent. After optimization of encapsulation and microcapsule loading, the self-healing microcapsules exhibited thermal stability under FROMP conditions and demonstrated a self-healing efficiency of 90% as measured by a conical double cantilever beam test. In one embodiment, stability was achieved by using a robust encapsulation system, a heat-resistant bis-N-heterocyclic (NHC)Ru-carbene precatalyst, and a Cu(I) activated coreagent.

[0010] On one hand, formulations for preparing self-healing polymers comprise a polymer precursor liquid and a dual-encapsulation system dispersed in the polymer precursor liquid. The dual-encapsulation system includes monomer microcapsules and catalyst microcapsules, each monomer microcapsule containing a monomer solution and an activator encapsulated in a shell, and each catalyst microcapsule containing a ruthenium catalyst and a solvent encapsulated in a shell.

[0011] In one embodiment, the shells of the monomer microcapsules and catalyst microcapsules have a degradation resistance temperature of at least 200°C and are thermally stable.

[0012] In one embodiment, the monomer solution contains monomers capable of ring-opening metathesis polymerization (ROMP). For example, the monomer solution may include unsaturated monomers with ring strain, such as, but not limited to, cyclopentadiene, cyclooctene, cyclooctadiene, dicyclopentadiene (DCPD), norbornene, and / or 5-ethylidene-2-norbornene (ENB). For example, the monomer solution may contain ENB at a concentration of up to 5 vol.%.

[0013] In one embodiment, the activator comprises metal ions capable of participating in metal transfer reactions. For example, the activator may include copper (Cu) ions.

[0014] In one embodiment, the ruthenium catalyst comprises a thermally latent Grubbs-based complex, such as a thermally latent Grubbs-type complex carrying two N-heterocyclic carbene ligands.

[0015] In one embodiment, the solvent comprises a high-boiling-point organic solvent. For example, the solvent may include phenylcyclohexane.

[0016] In one embodiment, the nominal width or diameter of the monomer microcapsules, catalyst microcapsules, or both is in the range of 1 micrometer to 800 micrometers. In one embodiment, the concentration of the monomer microcapsules and catalyst microcapsules in the polymer precursor liquid is in the range of about 1 wt.% to about 40 wt.%. In one embodiment, the concentration is at least 15 wt.%.

[0017] In one embodiment, the nominal thickness of the shell of each of the monomer microcapsules and catalyst microcapsules is in the range of about 20 nanometers to about 10 micrometers. In one embodiment, the shell of each of the monomer microcapsules and catalyst microcapsules has a multilayer structure. In one embodiment, the shell of each of the monomer microcapsules and catalyst microcapsules comprises one or more polymer layers and / or one or more ceramic layers. For example, the one or more polymer layers may comprise urea-formaldehyde, polymelamine, and / or polydopamine. In one embodiment, the one or more ceramic layers comprise silicon dioxide.

[0018] In one embodiment, the polymer precursor liquid comprises a thermosetting monomer and a ruthenium catalyst. For example, the ruthenium catalyst may be a Grubbs-based complex, and the monomer may be capable of frontier ring-opening metathesis polymerization (FROMP). For example, the monomer may be dicyclopentadiene (DCPD) and / or 5-ethylidene-2-norbornene (ENB). In one embodiment, the polymer precursor liquid comprises ENB at a concentration of up to 5 vol%.

[0019] In one embodiment, the polymer precursor liquid and the monomer microcapsules contain the same monomer. In another embodiment, the polymer precursor liquid and the monomer microcapsules contain different monomers.

[0020] In one embodiment, a rheology modifier (e.g., 5 wt.% fumed silica) is incorporated into the polymer precursor liquid to prevent or limit the segregation of microcapsules (e.g., gravity settling).

[0021] In one aspect, methods for preparing self-healing polymers include providing the formulation described herein and heating a polymer precursor liquid to achieve polymerization, wherein monomer microcapsules and catalyst microcapsules remain intact during heating, thereby forming a self-healing polymer.

[0022] In one embodiment, the step of heating the polymer precursor liquid to achieve polymerization is the FROMP process. In another embodiment, the step of heating the polymer precursor liquid to achieve polymerization includes initiating an exothermic polymerization reaction in the polymer precursor liquid and generating a self-propagating polymerization front moving through the polymer precursor liquid.

[0023] In one embodiment, the self-healing polymer comprises a thermosetting polymer. In one embodiment, the self-healing polymer comprises polydicyclopentadiene (p(DCPD)).

[0024] On one hand, the self-healing polymer comprises a polymer matrix and a dual-encapsulation system dispersed in a polymer precursor liquid. The dual-encapsulation system comprises monomer microcapsules and catalyst microcapsules, each monomer microcapsule containing a monomer solution and an activator encapsulated in the shell, and each catalyst microcapsule containing a ruthenium catalyst and a solvent encapsulated in the shell.

[0025] In one embodiment, the polymer matrix comprises a thermosetting polymer, such as pDCPD. In another embodiment, the polymer matrix is ​​an epoxy resin matrix, such as, but not limited to, Epon828+Epikure3223.

[0026] In one aspect, a method of using a self-healing polymer includes using a component comprising the self-healing polymer described herein in a remote location; exposing the self-healing polymer to mechanical forces or environmental conditions capable of causing damage during use of the component; and during exposure, forming a damaged region with the self-healing polymer, monomer microcapsules and catalyst microcapsules rupturing due to the damage, thereby mixing a monomer solution, an activator, and a ruthenium catalyst in the damaged region, and causing ring-opening metathesis polymerization to occur in the damaged region, thereby achieving self-healing of the component. For example, the remote location could be on the seabed, underground, in space, or inside the human body.

[0027] In one aspect, the formulation for preparing the self-healing polymer comprises a polymer precursor liquid, a thermally latent ruthenium catalyst (encapsulated) directly dispersed in the polymer precursor liquid, and monomer microcapsules dispersed in the polymer precursor liquid. Each monomer microcapsule contains a monomer solution and an activator encapsulated within a shell. Attached Figure Description

[0028] To facilitate a good understanding of this disclosure, various forms thereof will now be described by way of embodiment with reference to the accompanying drawings. Components in the drawings are not necessarily drawn to scale.

[0029] Figure 1 A cross-sectional view of a self-healing polymer matrix comprising monomer microcapsules and catalyst microcapsules according to one embodiment is shown.

[0030] Figure 2 An exemplary structure of the microcapsule is shown;

[0031] Figure 3 Scanning electron micrographs of monomeric microcapsules and catalyst microcapsules according to some embodiments are shown;

[0032] Figure 4 Thermogravimetric analysis (TGA) curves of exemplary monomer microcapsules and catalyst microcapsules are shown;

[0033] Figure 5 Infrared spectra of exemplary monomer microcapsules and catalyst microcapsules are shown;

[0034] Figure 6 A schematic diagram of frontier polymerization using microcapsules is shown, along with scanning electron micrographs of a matrix containing intact microcapsules and the same matrix damaged by a razor blade to release a repair agent from the microcapsules.

[0035] Figure 7 This demonstrates the effect of incorporating microcapsules into polymer precursors on the FROMP front velocity (V0). f ), frontal temperature (T) max ) and glass transition temperature (T g The effect of microcapsule loading varies with the amount of microcapsule loading.

[0036] Figure 8 Schematic diagrams of self-healing polymers containing dual-capsule systems, whether original, damaged, or repaired through self-healing, are shown, and tapered double cantilever beam (TDCB) tests were performed.

[0037] Figure 9 The TDCB test results of the original material, the repaired material, and the unrepaired material were compared, along with scanning electron micrographs of the repaired material; and

[0038] Figure 10 The experimental results of TDCB based on the control system of solvent welding material are shown. The solvent welding material is injected at the crack site using an exogenous monomer solution from a syringe.

[0039] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of this disclosure in any way. Detailed Implementation

[0040] The following description is exemplary in nature and is not intended to limit this disclosure, application, or use.

[0041] In the context of describing this disclosure (particularly in the context of the appended claims), the terms “a / an” and “the,” and similar designations, shall be construed as encompassing both the singular and the plural, unless otherwise indicated herein or clearly contradicted by the context. The applicant’s use of the term “plurality of” is defined in the broadest sense, superseding any other implied definition or limitation above or below, and means a quantity exceeding one unless the applicant expressly states otherwise. Unless otherwise indicated by the context, all methods described herein may be performed in any suitable order.

[0042] As those skilled in the art will understand, for any and all purposes, all ranges listed herein also encompass any and all possible subranges and combinations thereof, as well as the individual values ​​constituting the range, especially integer values. Therefore, it should be understood that each unit between two specific units is equally disclosed. For example, if “10 to 15” is disclosed, then 11, 12, 13, and 14 are also separately disclosed and as part of the range. Listed ranges (e.g., weight percentages or carbon groups) include every specific value, integer, decimal, or identity within that range. Any listed range can be readily identified as adequately describing the same range and such that the same range can be decomposed into at least equal halves, thirds, quarters, fifths, or tenths. As those skilled in the art will also understand, all language such as “up to,” “at least,” “greater than,” “less than,” “more than,” “or more,” etc., includes the listed numbers, and such terms refer to ranges that can subsequently be decomposed into subranges. Similarly, all ratios listed herein also include all subratios falling within a wider range. Therefore, the specific values ​​for groups, substituents, and ranges listed are for illustrative purposes only; these specific values ​​do not exclude other limiting values ​​for groups and substituents or other values ​​within the defined range. It will be further understood that the endpoints of each range are both clearly related to and clearly independent of the other endpoints.

[0043] Those skilled in the art will also readily recognize that, where members are grouped together in a common manner, such as in a Markush group, the invention includes not only the entire group listed as a whole, but also each member of that group individually, as well as all possible subgroups of the main group. Furthermore, for all purposes, the invention includes not only the main group, but also the main group missing one or more members. Therefore, the invention is contemplated to explicitly exclude any one or more members of the listed groups. Thus, the proviso can be applied to any one or more of the disclosed categories or instances, excluding any one or more of the listed elements, kinds, or instances from such categories or instances, for example, as a clear negative limitation.

[0044] As used herein, the terms “comprise,” “include,” “having,” “may,” “contain,” and their variations are intended as open-ended transitional phrases, terms, or words that do not preclude the possibility of additional actions or structures. This specification also considers other instances where, for instances or elements presented herein, “comprising,” “consisting of,” and “consisting essentially of” are used to qualify them, whether explicitly stated or not.

[0045] When describing the elements of this disclosure, the term "first (1)" may be used. st "Second (2)" nd "A", "B", "(a)", "(b)", etc. These terms are used only to distinguish one element from another, without restricting the corresponding element, regardless of its nature or order.

[0046] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. These terms, as defined in commonly used dictionaries, should be interpreted as having the same meaning as in the context of the relevant field.

[0047] As used herein, the term “about” when used in the context of the numerical value or range means a variation of ±15% or less of that value. For example, unless defined more narrowly in a particular context, values ​​differing by ±15%, ±14%, ±10%, or ±5% would satisfy the definition of “about”.

[0048] Unless otherwise stated, the term "front polymerization" refers to a method of propagating a polymerization reaction through a container or substance. There are three types of front polymerization: thermal front polymerization ("TFP"), which uses an external thermal energy source to initiate the front; photofront polymerization ("PFP"), where the local reaction is driven by an external UV source; and isothermal front polymerization ("IFP"), which relies on the Norrish-Trommsdorff or gel effect that occurs when monomers and initiators diffuse into polymer seeds (small polymer fragments). Thermal front polymerization begins when a heat source comes into contact with the monomer solution and the thermal initiator or catalyst. Alternatively, if a photoinitiator is also present, a UV source can be applied. The contact (or UV-exposed) region has a faster polymerization rate, and the energy from the exothermic polymerization diffuses into adjacent regions, raising the temperature and increasing the reaction rate at that location. The result is that the local reaction region propagates downwards along the reaction vessel as a heat wave.

[0049] Unless otherwise stated, the term "ring-opening metathesis polymerization (ROMP)" refers to a type of olefin metathesis chain-proliferation polymerization that produces industrially important products. The driving force of the reaction is the release of ring strain in cyclic olefins, which can be termed "functionalized cyclic olefins." Therefore, "front-end ring-opening metathesis polymerization (FROMP)" requires the conversion of monomers into polymers via locally exothermic reaction regions that propagate through a coupling of thermal diffusion and Arrhenius reaction kinetics. The pot life, gel time, and reaction kinetics can be controlled through various modifications to the polymerization chemistry.

[0050] As used herein, a “polymer precursor liquid” is a liquid at or near room temperature that contains chemical agents, such as monomers, oligomers, and optionally catalysts, that react to form a solid polymer network. In most cases, the chemical agents react only after the liquid has been stimulated (e.g., by heat or light).

[0051] As used in this article, “transmetalation” describes organometallic reactions involving the transfer of ligands from one metal to another.

[0052] As used herein, an "activator" is an element, ion, or compound that initiates a polymerization reaction. For example, an activator used in a ROMP reaction can be a metal or metal ion capable of participating in a metal transfer reaction using a ruthenium catalyst.

[0053] Examples of functionalized cyclic alkenes used in the FROMP reaction include, but are not limited to:

[0054] In one embodiment, the molar ratio of the amount of catalyst to the amount of functionalized cycloolefin may be less than about 1:100, or less than about 1:200, or less than about 1:300, or less than about 1:400, or less than about 1:500, or less than about 1:600, or less than about 1:700, or less than about 1:800, or less than about 1:900, or less than about 1:1000, or less than about 1:2000, or less than about 1:3000, or less than about 1:4000, or less than about 1:5000, or less than about 1:6000, or less than about 1:7000, or less than about 1:8000, or less than about 1:9000, or less than about 1:10000; or a range consisting of any two of the foregoing ratios; and any sub-ratios included therein.

[0055] In one embodiment, the catalyst may be a Grubbs catalyst or a Grubbs-type catalyst. Examples of suitable catalysts may include:

[0056] In one embodiment, heating the mixture may include applying a heat source to the mixture at a temperature of about 50°C to about 500°C, the temperature including, for example, from about 75°C, or from about 100°C, or from about 125°C, or from about 150°C, or from about 175°C, or from about 200°C, or from about 225°C, or from about 250°C, or from about 275°C, or from about 300°C, or from about 325°C, or from about 350°C, or from about 375°C, or from about 400°C, or from about 425°C, or from about 450°C. Or from about 475°C; or to about 75°C; or to about 100°C; or to about 125°C; or to about 150°C; or to about 175°C; or to about 200°C; or to about 225°C; or to about 250°C; or to about 275°C; or to about 300°C; or to about 325°C; or to about 350°C; or to about 375°C; or to about 400°C; or to about 425°C; or to about 450°C; or to about 475°C; or any temperature range consisting of any two of the foregoing temperatures; or any subranges therein.

[0057] Figure 1 A cross-sectional view of a self-healing polymer 100 comprising a polymer matrix 102, monomer microcapsules 104, and catalyst microcapsules 106 is shown. As shown, the microcapsules 104 and 106 are uniformly distributed throughout the matrix, although alternative distributions, such as gradient distributions, are also possible.

[0058] Figure 2The composition of an exemplary microcapsule is shown, which may be a catalyst microcapsule 106 or a monomer microcapsule 104. The microcapsule contains a self-healing core, which is typically a liquid core. For example, in the case of monomer microcapsule 104, the self-healing core may comprise a monomer solution and an activator, or in the case of catalyst microcapsule 102, the self-healing core may comprise a ruthenium catalyst and a solvent. The self-healing component in the core is surrounded by one or more encapsulation layers that are resistant to degradation (i.e., stable) under FROMP conditions forming the solid polymer matrix 102.

[0059] Figure 3 Scanning electron micrographs of monomer microcapsules 104 and catalyst microcapsules 106 according to some embodiments are shown. The monomer microcapsules shown contain a solution of DCPD monomer within a UF / SiO2 shell in an epoxy resin matrix. The catalyst microcapsules shown contain a thermally latent Grubbs-type complex dissolved in a solvent (phenylcyclohexane) within a UF shell in an epoxy resin matrix. The microcapsules contain reagents that undergo a self-healing process based on ring-opening metathesis (ROMP) when the microcapsules rupture and reagents from the core of the microcapsules mix. The liquid core ensures homogeneous mixing of the two-component repair system. Therefore, the liquids in the cores of the monomer and catalyst microcapsules are generally miscible with each other.

[0060] Thermogravimetric analysis (TGA) demonstrated the thermal stability of the microcapsules. Figure 4 The TGA curves of monomeric microcapsules and catalyst microcapsules are shown, along with a comparison of monomeric microcapsules with a single UF shell versus those with a UF / SiO2 double shell. All microcapsules are thermally stable at approximately 300 °C. Figure 5 The infrared spectra of monomer microcapsules and catalyst microcapsules are shown.

[0061] Figure 6 A schematic diagram of front-end polymerization using microcapsules dispersed in a polymer precursor (DCPD) is shown. When heat, indicated by the flame symbol, is applied to initiate FROMP, the polymer front advances away from the heat source in the direction indicated by the propagation arrow, and p(DCPD) forms behind the front. Scanning electron micrographs show a matrix containing intact catalyst and monomer microcapsules that persist in the FROMP at approximately 200°C, and that a remedial agent is released from the microcapsules when the same matrix is ​​scraped by a razor blade.

[0062] Figure 7 This demonstrates the effect of incorporating microcapsules into polymer precursors on the FROMP front velocity (V0). f ), frontal temperature (T) max ) and glass transition temperature (T gThe effect of microcapsule loading varies. Both the frontal velocity and frontal temperature decrease with increasing microcapsule loading, and the glass transition temperature of the polymer containing microcapsules is approximately 95°C at all loading levels, compared to approximately 130°C in the absence of microcapsules.

[0063] Figure 8 Schematic diagrams of self-healing polymers comprising a dual-capsule system, either pristine, damaged, or repaired through self-healing, are shown, along with tapered double cantilever beam (TDCB) tests. Self-healing reduces crack length and alters the slope of the load-displacement curve. Repair efficiency (η') is calculated using the internal work (or strain energy) from both pristine and repaired fracture tests.

[0064] Figure 9 TDCB test results of the original, repaired, and unrepaired materials were compared to determine the microcapsule loading required to restore mechanical properties. Microcapsule loadings of 15 wt.% or greater restored the original mechanical properties of p(DCPD). Scanning electron micrographs showed that the repair agent covered the fracture plane and repaired the damaged material.

[0065] Compared to the self-healing polymers described in this article, Figure 10 The TDCB experimental results for a solvent-based welding material, which was injected into the crack site using an exogenous monomer solution from a syringe, are shown. The solvent welding effect was insignificant, providing less than 5% repair efficacy. Conversely, as disclosed herein, using the same ROMP chemistry for both matrix fabrication and repair resulted in the formation of a favorable interface, thereby enhancing the overall self-healing properties.

[0066] The above compositions and methods can be better understood in conjunction with the following examples. Furthermore, the following non-limiting examples are illustrative. The procedures described as general methods are described in light of what is generally considered effective for preparing the illustrated compositions. However, those skilled in the art will understand that it may be necessary to modify the procedures of any given embodiment of this disclosure, for example, by changing the order or steps and / or the chemical reagents used. Example

[0067] Catalyst microcapsules were prepared from a catalyst / solvent mixture by vigorously emulsifying the catalyst / solvent mixture in a neutralized 1.75 wt.% poly(ethylene maleic anhydride) (EMA) surfactant solution for 10 minutes using a homogenizer.

[0068] Monomer microcapsules were prepared from an activator (e.g., CuCl) and a mixture of monomers DCPD / PCH (95 / 5 wt%) containing 2 wt.% antioxidant. The activator and mixture were vigorously stirred in a neutralized 1 wt.% EMA aqueous solution using an overhead mixer, and then dissolved in ascorbic acid.

[0069] Microcapsule shells were prepared as described below. A urea-formaldehyde (UF) prepolymer was synthesized by preparing a formaldehyde solution at pH 8 using triethanolamine and dissolving urea in this solution. The mixture was reacted at 70°C for 1 hour. The prepolymer solution was added to the emulsified mixture, and then 0.38 g of resorcinol was dissolved. After stabilization for 10 minutes, the emulsion was heated to 35°C, and when the temperature reached 30°C, the pH was adjusted to 2.5 using formic acid. The reaction was completed after 5 hours.

[0070] When pre-hydrolyzed TEOS is added after the UF reaction and the reaction is continued at 55°C for 5 hours, an additional SiO2 coating is added.

[0071] The synthesized microcapsules were washed in a centrifuge and then spray-dried (using a Buchi miniature spray dryer B-290) to produce free-flowing microcapsule powder.

[0072] The preparation of self-healing polymers involves mixing catalyst microcapsules and monomer microcapsules (e.g., 1 wt.% and 7.5 wt.% respectively) in a polymer precursor liquid and applying appropriate stimulation (e.g., heat or light) to initiate a frontier polymerization reaction.

[0073] Exemplary systems and methods are described by reference in the following literature incorporated herein by reference: Lee, Y. Betal., Adv. Mater. 2024, 36, 2309662.

[0074] Although this disclosure has been described with reference to embodiments and accompanying drawings, this disclosure is not limited thereto, but can be modified and varied by those skilled in the art without departing from the spirit and scope of this disclosure.

[0075] In addition to the features mentioned in each of the independent aspects listed above, some embodiments may individually or in combination illustrate optional features mentioned in the dependent aspects and / or disclosed in the above description and shown in the accompanying drawings.

Claims

1. Formulation for making a self-repairing polymer, the formulation comprising: a polymer precursor liquid; and a dual capsule system dispersed in the polymer precursor liquid, the dual capsule system comprising: monomer microcapsules, each of the monomer microcapsules comprising a monomer solution and an activator encapsulated in a shell; and a catalyst microcapsule, each of the catalyst capsules comprising a ruthenium catalyst and a solvent encapsulated in a shell.

2. The formulation of claim 1, wherein the shells of the monomer microcapsules and the catalyst microcapsules have a degradation resistance temperature of at least 200 °C, the shells being thermally stable shells.

3. The formulation of claim 1 or 2, wherein the monomer solution comprises monomers capable of ring-opening metathesis polymerization (ROMP).

4. The formulation of any one of the preceding claims, wherein the monomer solution comprises dicyclopentadiene (DCPD).

5. The formulation of any one of the preceding claims, wherein the monomer solution comprises 5-ethylidene-2-norbornene (ENB).

6. The formulation of claim 5, wherein the monomer solution comprises the ENB at a concentration of up to 5 vol. %.

7. The formulation of any one of the preceding claims, wherein the activator comprises a metal ion capable of a metal transfer reaction.

8. The formulation of any one of the preceding claims, wherein the activator comprises a copper ion.

9. The formulation of any one of the preceding claims, wherein the ruthenium catalyst comprises a thermally latent Grubbs-based complex.

10. The formulation of any one of the preceding claims, wherein the monomer microcapsules have a nominal width or diameter in the range of 1 micrometer to 800 micrometers.

11. The formulation of any one of the preceding claims, wherein the catalyst microcapsules have a nominal width or diameter in the range of 1 micrometer to 800 micrometers.

12. The formulation of any one of the preceding claims, wherein the concentration of the monomer microcapsules and the catalyst microcapsules in the polymer precursor liquid is in the range of 1 wt. % to 40 wt. %.

13. The formulation of any one of the preceding claims, wherein the shell of each of the monomer microcapsules and the catalyst microcapsules has a nominal thickness in the range of 20 nanometers to 10 micrometers.

14. The formulation of any one of the preceding claims, wherein the shell of each of the monomer microcapsules and the catalyst microcapsules has a multi-layer structure.

15. The formulation of any one of the preceding claims, wherein the shell of each of the monomer microcapsules and the catalyst microcapsules comprises one or more polymeric layers and / or one or more ceramic layers.

16. The formulation of claim 15, wherein the one or more polymeric layers comprise urea formaldehyde, poly melamine, and / or polydopamine.

17. The formulation of claim 15 or 16, wherein the one or more ceramic layers comprise silicon dioxide.

18. The formulation of any one of the preceding claims, wherein the polymer precursor liquid comprises: a thermally curable monomer; and a ruthenium catalyst.

19. The formulation of claim 18, wherein the ruthenium catalyst comprises a Grubbs- based complex.

20. The formulation of claim 18 or 19, wherein the monomer is capable of front- onset ring-opening metathesis polymerization (FROMP).

21. The formulation of any one of claims 18 to 20, wherein the monomer comprises dicyclopentadiene (DCPD).

22. The formulation of any one of claims 18 to 21, wherein the polymer precursor liquid comprises 5-ethylidene-2-norbornene (ENB).

23. The formulation of claim 22, wherein the polymer precursor liquid comprises the ENB at a concentration of up to 5 vol%.

24. A method of making a self-healing polymer, the method comprising: providing the formulation of any one of the preceding claims; and heating the polymer precursor liquid to effect polymerization, the monomer microcapsules and catalyst microcapsules remaining intact during the heating, thereby forming a self- healing polymer.

25. The method of claim 24, wherein the step of heating the polymer precursor liquid to effect polymerization comprises: initiating an exothermic polymerization reaction in the polymer precursor liquid; and generating a self-propagating polymerization front that moves through the polymer precursor liquid.

26. The method of claim 24 or 25, wherein the self-healing polymer comprises a thermoset polymer.

27. The method of any one of claims 24 to 26, wherein the self-healing polymer comprises polydicyclopentadiene (pDCPD).

28. A self-healing polymer, the self-healing polymer comprising: a polymer matrix; a dual microcapsule system dispersed in the polymer matrix, the dual microcapsule system comprising: monomer microcapsules, each of the monomer microcapsules comprising a monomer solution and an activator encapsulated in a shell; and catalyst microcapsules, each of the catalyst microcapsules comprising a ruthenium catalyst and a solvent encapsulated in a shell.

29. The self-healing polymer of claim 28, wherein the polymer matrix comprises a thermoset polymer.

30. The self-healing polymer of claim 28 or 29, wherein the polymer matrix comprises polydicyclopentadiene (pDCPD).

31. A method of using a self-healing polymer, the method comprising: using a component comprising the self-healing polymer of any one of claims 28 to 30 in a remote location; during use of the component, exposing the self-healing polymer to a mechanical force or environmental condition capable of causing damage; and during the exposing, forming a damaged region having the self-healing polymer, the monomer microcapsules and catalyst microcapsules rupturing, whereby the monomer solution, the activator, and the ruthenium catalyst are mixed in the damaged region, and ring-opening metathesis polymerization occurs in the damaged region, thereby effecting self- healing of the component.

32. The method of claim 31, wherein the remote location is in a subsea, subterranean, space, or human body.

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