Method for deconstructing an olefinic thermoset

Abstract

A method for deconstruction of an olefinic thermoset is provided in which the olefinic thermoset, an organic solvent, and a ruthenium metathesis catalyst are contacted under conditions effective to provide a deconstructed olefinic polymer composition. Methods for the manufacture of a recycled thermoset are also disclosed in which a virgin cyclic olefin monomer and a deconstructed olefinic polymer composition are polymerized in the presence of an olefin metathesis catalyst to provide the recycled thermoset.

Description

8519 PAG; SD16952.1 (103349-015PCT)METHOD FOR DECONSTRUCTING AN OLEFINIC THERMOSETCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 724,456, filed on November 25, 2024, the contents of which is hereby incorporated by reference in its entirety.FEDERAL RESEARCH STATEMENT

[0002] This invention was made with Government support under Contract No. DE- NA0003525 awarded by the United States Department of Energy / National Nuclear Security Administration, and under Contract No. DMR2045336 awarded by the National Science Foundation. The Government has certain rights in the invention.BACKGROUND

[0003] Thermoset polymers are indispensable in high-performance applications due to their superior mechanical, thermal, and chemical resistance properties relative to analogous thermoplastics. This arises from the covalent crosslinking within their polymer network structure, making thermosets ideal for adhesives, coatings, composites, electronic packaging, and vulcanized rubbers. Consequently, thermosets comprise approximately 18% of all polymers produced.

[0004] However, their crosslinked structures pose significant recycling challenges, often leading to landfill disposal or energy-intensive, highly polluting incineration methods. Developing sustainable end-of-life strategies for thermosets has therefore emerged as a pressing scientific and environmental priority. Among thermosets, poly(dicyclopentadiene) (pDCPD) is especially challenging to recycle due to its exceptional toughness, chemical inertness, and crosslink density.

[0005] Accordingly, there remains a continuing need in the art for improved recycling methods for thermoset polymers. It would be particularly advantageous to provide methods for recycling olefinic thermosets such as pDCPD.SUMMARY

[0006] A method for deconstruction of an olefinic thermoset, the method comprising: contacting the olefinic thermoset; an organic solvent; and a ruthenium metathesis catalyst; under conditions effective to provide a deconstructed olefinic polymer composition; wherein the8519 PAG; SD16952.1 (103349-015PCT) olefinic thermoset comprises less than 50 mole percent of repeat units derived from cyclopentene.

[0007] A method for the manufacture of a recycled thermoset, the method comprising: polymerizing a virgin cyclic olefin monomer; and a deconstructed olefinic polymer composition obtained by the method of the present disclosure; in the presence of an olefin metathesis catalyst to provide the recycled thermoset.

[0008] A recycled thermoset made by the method described herein represents another aspect of the present disclosure.

[0009] A recycled thermoset can be derived from a curable composition comprising a virgin cyclic olefin monomer; and a deconstructed olefinic polymer composition obtained by the method and comprising a macrocyclic compound; wherein the recycled thermoset comprises the macrocyclic compound or a cyclic derivative thereof.

[0010] The above described and other features are exemplified by the following figures and detailed description.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The following figures are exemplary embodiments.

[0012] FIG. 1 shows a schematic illustration of a process according to an aspect of the present disclosure.

[0013] FIG. 2 shows process optimization by solvent with environmental impact scores whereby a higher value is ‘greener’.

[0014] FIG. 3 shows process optimization by catalyst selection in an inert atmosphere.

[0015] FIG. 4 shows process optimization by catalyst selection in an ambient atmosphere

[0016] FIG. 5 shows kinetics of poly(dicyclopentadiene) (pDCPD) deconstruction as an effect of temperature.

[0017] FIG. 6 shows percent deconstruction and recovery for use of optimized conditions (225 millimolar (mM) in cyclopentyl methyl ether (CPME), 0.67 mole percent (mol%) second generation Hoyveda-Grubbs (HG2), 60 °C, and inert) for various manufacturing methods: ring -opening metathesis polymerization (ROMP), frontal ring -opening metathesis polymerization (FROMP) no post-cure, FROMP with post-cure, and photoROMP.

[0018] FIG. 7 shows a schematic illustration representing two hypothesized pathways for Metathesis Deconstruction of pDCPD; ring-closing metathesis of cyclopentene and chain transfer at double bonds in the crosslinks and main chains.8519 PAG; SD16952.1 (103349-015PCT)

[0019] FIG. 8 shows evolution of a tolucnc-ck solution (0.6 mL) containing Pl (pH2DCPD -co-DCPD-F, 30 mg) undergoing metathesis deconstruction (0.6 mg G2) as monitored by19F-NMR.

[0020] FIG. 9 shows gel permeation chromatography (GPC) spectra of pFbDCPD prior to and after metathesis deconstruction (~1.5 mol% G2).

[0021] FIG. 10 shows a comparison of Young’s Modulus (GPa) and ultimate tensile strength (UTS) from tensile testing dogbones (ASTM D638 Type V) of virgin pDCPD and pDCPD containing 20 weight percent (wt%) fragments recovered from metathesis deconstruction (MD).

[0022] FIG. 11 shows single fiber tensile test strength comparison of as-received vs. reclaimed carbon fiber post-MD processing.

[0023] FIG. 12 shows dynamic mechanical analysis of composites made using pristine and reclaimed carbon fibers.

[0024] FIG. 13 shows a process of encapsulating an electronic device in pDCPD and recovery via MD wherein the electronic maintains functionality.DETAILED DESCRIPTION

[0025] Derived from the ring-opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD), pDCPD is notable for its impact resistance and thermal stability, enabling its use in automotive panels, agricultural equipment, construction components, and marine infrastructure. It is applied widely in elastomeric ethylene-propylene-diene (EPDM) rubbers, soft robotics, and 3D printing applications such as direct ink writing (DIW), digital light processing (DLP), growth printing (GP), and solid-state volumetric printing. Moreover, DCPD is an abundant byproduct of naphtha steam cracking, comprising -9% of the C5+ fraction, which itself accounts for -18% of naphtha steam cracker output, yielding a global annual production on the order of approximately four and a half million metric tons.

[0026] Despite its versatility and abundance, the high durability of pDCPD severely limits recycling. Prior work has explored approaches such as chemical deconstruction through cleavable comonomers or bond-exchange like enol ethers, silyl ethers, or copolymerization with light-degradable units. However, these strategies require the use of synthetic comonomers and harsh deconstruction conditions (acid or high-intensity UV light) and are not aligned with standard commercial formulations. In contrast, metathesis deconstruction (MD) processes offer more direct and facile strategies by utilizing catalysts that react with the polymer alkenes in order to break down the crosslinked network into monomers, oligomers, and cyclooligomers.8519 PAG; SD16952.1 (103349-015PCT)These lower molecular weight products can be solubilized and reprocessed into next generation products. For example, degradation of cyclopentene-DCPD copolymers using Grubbs second generation catalyst (G2) at 1.0 mol% loading in toluene at 60 °C has been demonstrated. Other methods use a chain transfer agent approach to promote upcycling of pDCPD via formation of alcohol-functionalized telechelic oligomers using G2 at 0.25 mol% in toluene at 120 °C. These prior MD strategies for thermosets have leveraged ring-closing metathesis of cyclopentene, chain transfer agents, and designer monomers, there remains a critical need for accessible and generalizable methods applicable to recycle industrially relevant pDCPD.

[0027] The present inventors have discovered a method for degradation of an olefinic thermoset, such as pDCPD, using commercially available ruthenium metathesis catalysts. Advantageously, the method can be conducted in “green” solvents, and thus is more environmentally friendly than prior processes. An exemplary schematic illustration of the process according to an aspect of the present disclosure is shown in FIG. 1. The present inventors have optimized the process for economic viability, elucidating the detailed deconstruction mechanism and fragment composition, and validating the approach with real- world commercial pDCPD samples, carbon-fiber composites, and encapsulated electronics. A life-cycle assessment id further provided, highlighting the sustainability and translatability of the present method. The present disclosure establishes a comprehensive, practical, and broadly applicable platform for olefinic thermoset deconstruction, thermoset matrix removal, and efficient recycling into next-generation products. A significant improvement is therefore provided by the present disclosure.

[0028] Accordingly, an aspect of the present disclosure is a method for deconstruction of an olefinic thermoset. The olefinic thermoset is a crosslinked polymeric material containing carbon-carbon double bonds (olefinic groups) in its backbone or network structure, which is formed through a polymerization process and is insoluble and infusible upon curing. The olefinic thermoset can be provided by polymerization of a cyclic olefin monomer, which may be polymerized using various ring-opening metathesis polymerization methods.

[0029] Preferably, the olefinic thermoset comprises poly(dicyclopentadiene), a copolymer thereof, or a derivative thereof. A poly(dicyclopentadiene) thermoset refers to a polymer or copolymer obtained by ring-opening metathesis polymerization of dicyclopentadiene, resulting in a rigid, highly crosslinked network containing residual or newly formed olefinic bonds. Optionally, dicyclopentadiene can be copolymerized in the presence of one or more additional cyclic olefin monomers, such as, but not limited to, cyclooctene, norbomene, cyclopentene, cyclooctadiene, tricyclopentadiene, or a derivative thereof, or a8519 PAG; SD16952.1 (103349-015PCT) combination thereof.

[0030] In some aspects, the olefinic thermoset is poly(dicyclopentadiene) and no additional comonomers are present (i.e., a homopolymer). In some aspects, the olefinic thermoset is a copolymer comprising repeating units derived from dicyclopentadiene and one or more additional cyclic olefins. Preferably the olefinic thermoset comprises less than 50 mole percent of repeat units derived from cyclopentene, for example less than 40 mole percent, or less than 30 mole percent, or less than 20 mole percent, or less than 10 mole percent, or less than 1 mole percent of repeat units derived from cyclopentene. In some aspects, the olefinic thermoset is devoid of repeat units derived from cyclopentene.

[0031] The olefinic thermoset can optionally comprise one or more additives typically present in thermoset materials with the proviso that the one or more additives do not significantly adversely affect a desired property of the olefinic thermoset or its deconstruction by the method disclosed herein. Suitable additives include, for example, dyes, pigments, colorants, antioxidants, heat stabilizers, light stabilizers, plasticizers, lubricants, flow modifiers, drip retardants, flame retardants, antiblocking agents, antistatic agents, flow-promoting agents, processing aids, substrate adhesion agents, mold release agents, toughening agents, low-profile additives, stress-relief additives, inorganic fillers, or a combination thereof.

[0032] In an aspect, the olefinic thermoset can comprise an inorganic filler. Suitable inorganic fillers include, for example, alumina, silica (including fused silica and crystalline silica), boron nitride (including spherical boron nitride), aluminum nitride, silicon nitride, magnesia, magnesium silicate, glass fibers, glass mat, carbonaceous materials (e.g., carbon fiber, graphite, graphene, carbon nanotubes (single-walled or multi-walled), carbon black, activated carbon, pyrolytic carbon, and mesophase pitch-derived carbon materials), or a combination thereof. Suitable glass fibers include those based on E, A, C, ECR, R, S, D, and NE glasses, as well as quartz. The glass fiber can have a diameter of 2 to 30 micrometers, preferably 5 to 25 micrometers, more preferably 5 to 15 micrometers. The length of the glass fibers before compounding can be 2 to 7 millimeters, preferably 1.5 to 5 millimeters. Alternatively, longer glass fibers or continuous glass fibers can be used. The glass fiber can, optionally, include an adhesion promoter to improve its compatibility with the olefinic thermoset. Adhesion promoters include chromium complexes, silanes, titanates, zircon-aluminates, propylene maleic anhydride copolymers, reactive cellulose esters, and the like.

[0033] In an aspect, the olefinic thermoset can be provided as a composite material by incorporating a reinforcing filler or fiber in the olefinic polymer matrix prior to or during curing. Exemplary reinforcing fillers can be as described above. In an aspect, the reinforcing material8519 PAG; SD16952.1 (103349-015PCT) can comprise glass fibers, carbon fibers, aramid fibers, natural fibers, or woven or non-woven fabrics comprising such fibers. The reinforcement can be present in the form of short fibers, continuous fibers, mats, fabrics, or preforms, and may be randomly oriented, aligned, or layered to achieve desired mechanical, thermal, or dimensional properties.

[0034] In an aspect, the olefinic thermoset can be provided as an encapsulant, wherein an article or component is at least partially or fully surrounded by, embedded in, or coated by the olefinic thermoset. Exemplary articles or components can include, but are not limited to, electronic components such as circuit boards, semiconductors, connectors, or sensors, as well as other devices requiring protection from mechanical stress, moisture, chemicals, or thermal exposure. The olefinic thermoset encapsulant provides a rigid, crosslinked, and insoluble coating or matrix that secures, protects, and electrically insulates the article while maintaining the desirable mechanical, thermal, and chemical properties of the polymer. It can be desirable to remove the olefinic thermoset encapsulant and recover the article or component, whereby the article or component retains its functionality after then encapsulant is removed. For example, where the encapsulated component is an electronic component such as a circuit board, the circuit board can retain its functionality after removal of the encapsulating olefinic thermoset via the metathesis deconstruction method provided herein.

[0035] The method for deconstructing the olefinic thermoset comprises contacting the olefinic thermoset with an organic solvent and a ruthenium metathesis catalyst. The olefinic thermoset is not soluble in the organic solvent, but optionally may be swellable. The organic solvent can solubilize the deconstructed olefinic polymer composition (e.g., the linear or cyclic olefin oligomers that result from the deconstruction). In some aspects, the organic solvent can comprise an aromatic solvent (e.g., benzene, chlorobenzene, toluene, xylene, and the like, a derivative thereof, or a combination thereof), a cyclic ether solvent (e.g., tetrahydrofuran, or the like), or a hydrophobic ether solvent (e.g., cyclopentyl methyl ether). In some aspects, cyclopentyl methyl ether can be used as a solvent due to its favorable environmental and safety profile, including low toxicity, high chemical and thermal stability, reduced volatility, minimal peroxide formation, and improved biodegradability, making it an eco-friendly alternative to conventional organic solvents.

[0036] The olefinic thermoset and the organic solvent can generally be provided in any suitable amounts. In an aspect the olefinic thermoset and the organic solvent can be provided in amounts effective to provide an olefin repeat unit concentration of 1 millimole per liter of organic solvent to 2 moles per liters of organic solvent, for example, 1 millimole per liter of organic solvent to 1 mole per liter of organic solvent, or 1 to 500 millimoles per liter of organic8519 PAG; SD16952.1 (103349-015PCT) solvent, or 25 to 500 millimoles per liter of organic solvent, or 50 to 500 millimoles per liter of organic solvent, or 75 to 500 millimoles per liter of organic solvent. In an aspect, the olefinic thermoset and the organic solvent can be provided in amounts effective to provide an olefin repeat unit concentration of 100 to 500 millimoles per liter of organic solvent. In an aspect, the concentration can be at least 1, or at least 25, or at least 50, or at least 75, or at least 100, or at least 150, or at least 200, or at least 250, or at least 300, or at least 350, or at least 400 millimoles per liter of organic solvent. Also within this range, the concentration can be at most 450, or at most 400, or at most 350, or at most 300, or at most 275, or at most 250, or at most 200, or at most 150, or at most 100, or at most 75 millimoles per liter of organic solvent. In an aspect, the concentration can be 150 to 300 millimoles per liter of organic solvent.

[0037] The term “ruthenium metathesis catalyst” as used herein refers to a transition metal complex comprising a ruthenium center coordinated to one or more ligands capable of promoting an olefin metathesis reaction, including ring-opening metathesis polymerization (ROMP), cross-metathesis, or ring -closing metathesis. The one or more ligands can comprise stabilizing ligands (e.g., phosphines, N-heterocyclic carbenes, and the like) and labile ligands (e.g., halides, alkylidene groups, and the like) that facilitate the reversible cleavage and reformation of carbon-carbon double bonds.

[0038] Representative ruthenium-based metathesis catalysts include, without limitation, Grubbs first-generation catalysts (e.g., bis(tricyclohexylphosphine)benzylidene ruthenium dichloride), Grubbs second-generation catalysts (e.g., N-heterocyclic carbene-substituted benzylidene ruthenium dichloride), Grubbs third-generation catalysts (e.g., N-heterocyclic carbene-substituted benzylidene ruthenium complexes bearing labile pyridine or phosphine ligands), Hoveyda-Grubbs catalysts (e.g., chelated benzylidene ruthenium complexes bearing an alkoxy or aryloxy ligand), nitro-Grela-I2 catalysts (e.g., ruthenium benzylidene complexes containing an electron-withdrawing nitro-substituted chelating ligand), and related derivatives thereof. Additional suitable catalysts include ruthenium complexes bearing phosphine, N- heterocyclic carbene, or pyridine ligands, as well as functionalized variants designed to enhance activity, selectivity, or thermal stability in ring-opening metathesis polymerization of strained cyclic olefins. In a specific aspect, the ruthenium metathesis catalyst comprises a second generation Hoveyda-Grubbs catalyst (dichloro[l,3-bis(2,4,6-trimethylphenyl)-2- imidazolidinylidene]-(2-isopropoxystyrene)ruthenium(II)). The particular catalyst can be selected based on the chemical identity of the olefinic thermoset, the organic solvent, the desired reaction conditions (e.g., reaction time and temperature), and desired extent of deconstruction or recovery, as shown herein.8519 PAG; SD16952.1 (103349-015PCT)

[0039] The ruthenium catalyst can be present in an amount effective to provide a concentration of 0.001 to 5 mole percent, based on total moles of olefin repeat units. Within this range, the ruthenium catalyst can be present in an amount effective to provide a concentration of at least 0.01, or at least 0.05, or at least 0. 1, or at least 0.2, or at least 0.5, or at least 0.6, or at least 0.7, or at least 0.75, or at least 0.8 mole percent, based on total moles of olefin repeat units. Also within this range, the ruthenium catalyst can be present in an amount effective to provide a concentration of at most 4.5, or at most 4, or at most 3.5, or at most 3, or at most 2.5, or at most 2, or at most 1.5, or at most 1, or at most 0.95, or at most 0.9, or at most 0.85, or at most 0.8, or at most 0.75, or at most 0.7 mole percent, based on total moles of olefin repeat units. In an aspect, the ruthenium catalyst can be present in an amount effective to provide a concentration of 0.5 to 1 mole percent, based on total moles of olefin repeat units. In an aspect, the ruthenium catalyst can be present in an amount effective to provide a concentration of 0.5 to 0.75 mole percent, based on total moles of olefin repeat units. In some aspects, it may be desirable to reduce the amount of catalyst used, for example due to cost, and thus lower amounts of catalyst are also contemplated by the present disclosure.

[0040] The olefinic thermoset, the organic solvent, and the ruthenium catalyst are contacted under conditions effective to provide a deconstructed olefinic polymer composition. The effective conditions can include, for example, a temperature of 20 to 100°C. Within this range, the temperature can be, for example, 20 to 80°C, or 40 to 100°C, or 40 to 80°C. The contacting can be for any suitable time, for example for at least 30 minutes, or 30 minutes to 72 hours, or 30 minutes to 50 hours, or 1 hour to 72 hours, or 1 hour to 50 hours. In an aspect, the contacting can be under an inert atmosphere, for example, under nitrogen, argon, or other inert atmosphere, preferably which is free of oxygen. In an aspect, the contacting can be under ambient conditions, for example in the presence of oxygen.

[0041] The method can further comprise deactivating the ruthenium metathesis catalyst. The quenching step may comprise contacting the reaction mixture with a quenching agent effective to deactivate the ruthenium metathesis catalyst. Suitable quenching agents include, but are not limited to, alkyl vinyl ethers such as ethyl vinyl ether, benzaldehyde, alcohols, or other compounds capable of reacting with the catalyst carbene moiety to form an inactive complex. The quenching agent may be added in an amount sufficient to ensure complete deactivation of the catalyst, for example, in a molar excess relative to the catalyst concentration. The quenched reaction mixture may be stirred for a period of time effective to achieve full termination of the deconstruction and provide the deconstructed olefinic polymer composition.

[0042] The deconstructed olefinic polymer composition comprises a linear oligomer8519 PAG; SD16952.1 (103349-015PCT) derived from the olefinic thermoset, a cyclic oligomer derived from the olefinic thermoset, a cyclic olefin monomer derived from the olefinic thermoset, or a combination thereof. In an aspect, when the olefinic thermoset comprises poly(dicyclopentadiene), the deconstructed olefinic polymer composition can comprise one or more oligomer structures according to formulas (I)-(III)As will be understood by one of skill in the art, the repeat unit structure indicated by formula (III) can be present together with the repeat unit structure shown in the cyclic oligomer of formula (I) or can be present together with the repeat unit structure shown in the linear oligomer of formula (II). As further described in the working examples below, the metathesis deconstruction process can proceed by multiple pathways, including backbone metathesis and ring closing metathesis of cyclopentene units, giving rise to the deconstructed oligomer composition with some variation in oligomer architecture (linear or cyclic) and repeat unit structure.

[0043] In an aspect, the deconstructed olefinic polymer composition comprises a linear oligomer derived from the olefinic thermoset and a cyclic oligomer derived from the olefinic thermoset. In an aspect, the deconstructed olefinic polymer composition can comprise 1 to 99 mole percent of the linear oligomer derived from the olefinic thermoset and 1 to 99 mole percent of the cyclic oligomer derived from the olefinic thermoset, based on total moles of repeat units of the deconstructed olefinic polymer composition. For example, the deconstructed olefinic polymer composition can comprise 5 to 75, or 10 to 60, or 10 to 50, or 10 to 40 mole percent of the linear oligomer, and 25 to 95, or 40 to 90, or 50 to 90, or 60 to 90 mole percent of the cyclic oligomer.

[0044] The linear and cyclic oligomers are substantially free of crosslinks. The linear or cyclic oligomers can have varying molecular weight but are such that the oligomers can be solubilized in the organic solvent. Stated another way, the deconstructed olefinic polymer composition can form a single homogeneous phase, for example at an olefin repeat unit concentration of 100 to 500 millimoles per liter of organic solvent and a temperature of 20 to 25°C, without the formation of undissolved particles, precipitate, or phase separation. It will be understood that the linear oligomer derived from the olefinic thermoset, the cyclic oligomer derived from the olefinic thermoset, or the combination thereof are soluble in the organic8519 PAG; SD16952.1 (103349-015PCT) solvent. However, when certain additives, for example reinforcing fdlers, are present in the olefinic thermoset, such additives may be suspended in the solvent. Precipitated additives can optionally be recovered for further use, as further described in the working examples.

[0045] Advantageously, the method provided herein can provide high levels of deconstruction of the olefinic thermoset (e.g., a high percent conversion to the deconstructed product mixture). For example, the deconstructed olefinic polymer composition can retain at least 85 weight percent, or at least 90 weight percent, or at least 95 weight percent, or at least 97 weight percent, or at least 99 weight percent of an initial weight of the olefinic thermoset. Stated another way, at least 85 weight percent of the initial olefinic thermoset can be converted to the deconstructed olefinic polymer composition.

[0046] The method can optionally further comprise recovering the deconstructed olefinic polymer composition. Recovering the deconstructed olefinic polymer composition can comprise decanting and optionally filtering the organic solvent comprising solubilized deconstructed product to remove non-soluble olefinic thermoset starting material, if present. The mixture comprising the organic solvent and the solubilized deconstructed product (and catalyst residue) can be contacting with a polar solvent to precipitate the deconstructed polymer composition. Any suitable polar solvent can be used provided that it is miscible with the organic solvent and the deconstructed product is insoluble. Exemplary polar solvents can include, for example, an alcoholic solvent such as methanol, ethanol or isopropanol, a ketone solvent such as acetone, an ether solvent such as diethyl ether, and the like, or mixtures thereof.

[0047] Precipitated deconstructed olefinic polymer composition can be isolated using any suitable solid-liquid separation technique, for example filtration, centrifugation, or a combination thereof.

[0048] In a further advantageous feature, method provided herein can result in high levels of recovery of the deconstructed olefinic polymer composition. For example, the deconstructed olefinic polymer composition can be recovered in a yield of at least 75 weight percent, or at least 80 weight percent, or at least 85 weight percent, or at least 90 weight percent, or at least 95 weight percent, each based on an initial weight of the olefinic thermoset.

[0049] In a further advantageous feature, when the olefinic thermoset comprises a reinforcing layer, reinforcing fibers, or reinforcing particulate fillers, the layer, fibers, and fillers can be separated and recovered from the deconstructed product. The recovered reinforcing layer, fibers, and fillers can subsequently be recycled for further use in new composites (e.g., prepared from virgin materials, recycled materials or a combination thereof). Recovery and reuse of reinforcing fibers is further shown and discussed in the working examples below.8519 PAG; SD16952.1 (103349-015PCT)

[0050] The present inventors have further discovered that recovered deconstructed olefinic polymer composition can be useful in the preparation of recycled materials. For example, the deconstructed olefinic polymer composition can be re-polymerized in the presence of an olefin metathesis catalyst to provide a recycled olefinic thermoset. Any suitable olefin metathesis catalyst can be used for preparing the recycled thermoset, including the ruthenium catalysts already discussed herein. Other suitable metathesis catalysts can include, for example, those having a transition metal -carbene complex comprising a metal such as molybdenum, tungsten, or osmium.

[0051] The polymerization may be conducted in a suitable organic solvent such as toluene, dichloromethane, benzene, or mixtures thereof, or under neat (bulk) conditions. The reaction temperature may be selected based on the desired polymer structure and catalyst activity, and may range from 0 to 100°C, or 20 to 70°C. The polymerization may proceed for a time sufficient to achieve the desired monomer conversion or molecular weight, for example from several minutes to several hours. Upon completion, the reaction may be quenched by addition of a quenching agent such as an alkyl vinyl ether, alcohol, or other compound capable of deactivating the metal-carbene species. The resulting polymer may then be isolated by precipitation into a non-solvent, filtration, or solvent removal under reduced pressure.

[0052] Optionally, re-polymerization can be in the presence of a virgin cyclic olefin monomer to provide a recycled thermoset having a desired content of recycled material. The virgin cyclic olefin monomer can comprise any suitable cyclic olefin for ring-opening metathesis polymerization including dicyclopentadiene, norbomene, norbomadiene, cyclooctene, cyclooctadiene, cyclopentene, tricyclopentadiene, and the like, or a derivative thereof, or a combination thereof. In a specific aspect, the deconstructed olefinic polymer composition can comprise linear or cyclic oligomers having repeating units derived from dicyclopentadiene, and the virgin cyclic olefin monomer can comprise virgin dicyclopentadiene.

[0053] In an aspect, the method can comprise polymerizing a reaction mixture comprising 1 to 99 weight percent of the deconstructed olefinic polymer composition and 1 to 99 weight percent of the virgin cyclic olefin monomer, each based on total weight of the reaction mixture to provide a corresponding recycled thermoset material. For example, the method can comprise polymerizing a reaction mixture comprising 10 to 99, or 20 to 99, or 30 to 99, or 40 to 99, or 50 to 99, or 60 to 99, or 70 to 99 weight percent of the deconstructed olefinic polymer composition and 1 to 90, or 1 to 80, or 1 to 70, or 1 to 60, or 1 to 50, or 1 to 40, or 1 to 30 weight percent of the virgin cyclic olefin monomer, each based on total weight of the reaction mixture to provide a corresponding recycled thermoset material.8519 PAG; SD16952.1 (103349-015PCT)

[0054] Accordingly, the recycled thermoset can be derived from 1 to 99 weight percent of the deconstructed olefinic polymer composition and 1 to 99 weight percent of the virgin cyclic olefin monomer, each based on total weight of the recycled thermoset material. For example, the recycled thermoset can be derived from 10 to 99, or 20 to 99, or 30 to 99, or 40 to 99, or 50 to 99, or 60 to 99, or 70 to 99 weight percent of the deconstructed olefinic polymer composition and 1 to 90, or 1 to 80, or 1 to 70, or 1 to 60, or 1 to 50, or 1 to 40, or 1 to 30 weight percent of the virgin cyclic olefin monomer, each based on total weight of the recycled thermoset material.

[0055] The present inventors have unexpectedly found that the recycled thermosets described herein can exhibit a desirable combination of physical properties. For example, the recycled thermoset can have a Young’s modulus that is within 20%, preferably within 10% of a Young’s modulus for a corresponding virgin thermoset (i.e., a thermoset of substantially the same chemical composition except prepared solely from virgin materials). In an aspect, the recycled thermoset can have an ultimate tensile strength that is within 20%, preferably within 10% of an ultimate tensile strength for a corresponding virgin thermoset, determined according to ASTM D638 Type V. In a specific aspect, the recycled thermoset can include up to 20 weight percent of recycled material (e.g., derived from the deconstructed olefinic polymer composition of the present disclosure) and can exhibit a Young’s modulus that is within 20%, preferably within 10% of a Young’s modulus for a corresponding virgin thermoset, and an ultimate tensile strength that is within 20%, preferably within 10% of an ultimate tensile strength for a corresponding virgin thermoset, determined according to ASTM D638 Type V. In another specific aspect, the recycled thermoset can comprise repeating units derived from dicyclopentadiene and comprise up to 20 weight percent of recycled material (e.g., derived from the deconstructed olefinic polymer composition of the present disclosure and comprising repeating units derived from dicyclopentadiene), and can exhibit a Young’s modulus that is within 20%, preferably within 10% of a Young’s modulus for a corresponding virgin thermoset, and an ultimate tensile strength that is within 20%, preferably within 10% of an ultimate tensile strength for a corresponding virgin thermoset, determined according to ASTM D638 Type V.

[0056] As discussed above, the deconstructed olefinic polymer composition can comprise a cyclic oligomer deconstruction product. As such, a recycled thermoset material derived from the deconstructed olefinic polymer composition of the present disclosure can include a cyclic oligomer deconstruction product, also referred to herein as a macrocyclic compound. Accordingly, the recycled thermoset derived from a curable composition comprising a virgin cyclic olefin monomer and a deconstructed olefinic polymer composition obtained by8519 PAG; SD16952.1 (103349-015PCT) the present method, wherein the deconstructed olefinic polymer composition comprises a macrocyclic compound represents another aspect of the present disclosure. The resulting thermoset can comprise the macrocyclic compound or a macrocyclic derivative thereof. The present inventors have unexpectedly found that despite the presence of this macrocyclic compound, the recycled thermoset retains good mechanical properties, for example Young’s modulus and ultimate tensile strength as described above.

[0057] The concentration of the macrocyclic compound within the recycled thermoset material can vary depending, for example, on the deconstruction reaction conditions and thus the composition of the deconstruction reaction product. Thus the mount of the macrocyclic compound present in the resin composition is not specifically limited. In some aspects, the recycled thermoset material may include up to 10 weight percent of a macrocyclic compound (e.g., that is derived from the cyclic oligomer deconstruction product). For example, the recycled thermoset material can comprise 1 to 10 weight percent of the macrocyclic compound.

[0058] This disclosure is further illustrated by the following examples, which are nonlimiting.EXAMPLES

[0059] An optimized method for pDCPD thermoset deconstruction and recovery was developed through a series of experiments designed to evaluate the effects of solvent, catalyst choice, atmosphere (inert vs. ambient), and temperature. All experiments were conducted at a DCPD repeat unit concentration of ~225 mM (approx. 450 ± 50 mg in 15 mb) to minimize solvent use as excess solvent increases purification cost, largely outweighing the emissions and cost savings in alternative solvolysis approaches. It has been previously noted that more concentrated MD conditions can yield a broader distribution of deconstruction products as a potential trade-off. Deconstruction efficiency was assessed by gravimetric analysis of residual solid material after treatment, followed by precipitation of solubilized fragments to determine recovery values.

[0060] To identify solvents that enable complete MD of pDCPD while minimizing environmental impact, pDCPD samples were first swollen in a panel of solvents for 12 hours, followed by the addition of Hoveyda-Grubbs 2nd generation catalyst (HG2, 0.67 mol% based on pDCPD) at room temperature. The solvents tested included toluene, xylenes, cyclopentyl methyl ether (CPME), tetrahydrofuran (THF), methyl-tetrahydrofuran (Me-THF), limonene, dichloromethane (DCM), and NeoClear, a commercial xylenes substitute. Notably, the only three solvents to facilitate complete deconstruction at room temperature for three days were8519 PAG; SD16952.1 (103349-015PCT) toluene, xylenes, and CPME (FIG. 2). CPME was selected for further studies, as the use of CPME resulted in clean precipitations. Furthermore, separation and recovery of CPME form methanol is routinely conducted on an industrial scale as methanol is required for the synthesis of CPME. CPME also has reported green solvent characteristics including improved environmental impact score, low toxicity, and low peroxide formation, making it preferable for scalable and sustainable processes.

[0061] Utilizing CPME as the solvent, a set of ruthenium-based metathesis catalysts were screened. Grubbs type ruthenium alkylidene metathesis catalysts were the focus of this study for their balance of reactivity and air-stability. Grubbs 1st generation (Gl), Grubbs 2nd generation (G2), Grubbs 3rd generation (G3), Hoveyda-Grubbs 1st generation (HG1), Hoveyda- Grubbs 2nd generation (HG2), and nitro-Grela-b (nGb) catalyst were utilized. Under an inert atmosphere at room temperature, all catalysts except HG1 facilitated substantial deconstruction over a period of three days, with percent deconstruction of 99.6 ± 0.2, 99. 1 ± 0.3, 92 ± 7, 30 ± 10, 98.5 ± 0.4, and 98. 1 ± 0.7 % and percent recovery of 98.9 ± 0.8, 98 ± 1, 90 ± 3, 27 ± 7, 92 ± 4, and 97.2 ± 0.3 % for Gl, G2, G3, HG1, HG2, and nGU, respectively (FIG. 3). In an ambient atmosphere, nGU was the only catalyst to achieve near complete deconstruction, with percent deconstruction of 40 ± 20, 13 ± 5, 5 ± 10, I ± 1, 40 ± 10, and 83 ± 10 % and percent recovery of 40 ± 20, 20 ± 7, 8 ± 10, 8.1 ± 0.7, 16 ± 6, and 80 ± 10 % for Gl, G2, G3, HG1, HG2, and nGb, respectively (FIG. 4).

[0062] Given HG2's oxygen-ruthenium chelate and ring-closing metathesis (RCM) activity, it was selected for further study under an ambient atmosphere. It was hypothesized that increasing the temperature would enhance the deconstruction rate enough to outpace catalyst deactivation caused by exposure to air. A range of temperatures from room temperature (RT) to 100 °C were tested with kinetic experiments with complete deconstruction occurring in approximately 72, 48, 24, 3.5, and 2 h for RT, 40, 60, 80, and 100 °C, respectively, under inert conditions at 225 mM (FIG. 5). When repeated in ambient atmosphere with catalyst and solvent solution prepared on the bench, near quantitative deconstruction (>95 %) with HG2 in CPME was successfully achieved within 72 h at all temperatures above 60 °C, validating our hypothesis. Screening catalyst loading of HG2 in both inert and ambient atmospheres at RT revealed a dramatic difference in ability to deconstruct pDCPD samples. In going from 2 to 0.10 mol% HG2 (constant volume of CPME), a decrease in percent deconstruction was measured for samples under inert and ambient conditions (98.6 ± 0.1 to 70 ± 30 % and 96 ± 3 to 0 ± 1 %, respectively). By heating 0.10 mol% inert samples from 40 to 100 °C, complete deconstruction was achieved indicating that lower loadings can be employed successfully for MD when heated.8519 PAG; SD16952.1 (103349-015PCT)

[0063] To assess the robustness of the deconstruction platform across subtly different network structures, pDCPD samples were prepared by multiple manufacturing methods: FROMP with and without thermal post-cure, photoROMP, and ROMP with thermal post-curing. Deconstruction performance, utilizing ‘optimized’ conditions (225 mM in CPME, HG2 (0.67 mol%), 60 °C, and inert), was consistent across all manufacturing methods with observed deconstruction values -95% and recovery values -80% (FIG. 6).

[0064] Matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF) enabled structural analysis of deconstruction fragments after pDCPD samples, with and without ENB copolymerization, were treated to MD (inert, G2 or HG2, RT). We applied the Modular Operations for Spectral Alignment by Iterative Compression (MOSAIC) method to identify nonconstitutional repeating units (e.g., chain-ends, adducted ions) in the resulting oligomers. MOSAIC employs modular arithmetic to subtract monomer-derived mass contributions, thereby aligning homologous series of identical nonconstitutional repeating units horizontally in plots of remainder mass vs. m / z. This analysis revealed that most peaks correspond to cyclooligomers lacking chain-ends, with remainder masses matching the Ag+counterion from the MALDI matrix. A minor series of linear oligomers with benzylidene (=CHPh) termini on both ends was also observed. Substitution of G2 for the Hoveyda-Grubbs second-generation catalyst (HG2) again predominantly resulted in signals corresponding to cyclooligomers, along with linear oligomers bearing catalyst-derived o-isopropoxybenzylidene end groups. It is noted that MALDI-TOF shows bias to species more readily ionized and should not be used as conclusive evidence, yet the predominance of cyclooligomer series supports the hypothesis that metathesis deconstruction proceeds through chain transfer at one or both types of C=C bonds present in the pDCPD network in addition to the previously hypothesized ringclosing of the cyclopentene moiety (FIG. 7).

[0065] During polymerization, DCPD primarily incorporates the bridged bicyclic alkenes (norbomenyl-type) into the polymer main chain, while ring-opening of the cyclopentenyl double bonds occurs to a lesser extent, forming crosslinks. To directly probe the crosslinking sites derived from opened cyclopentenyl alkenes, a fluorinated copolymer, Pl, was designed that mimics the crosslink structure found in pDCPD (FIG. 8). Pl was synthesized via FROMP using a mixture of FhDCPD and a19F-labeled DCPD analog (DCPD-F) containing both a cyclopentenyl ring and a fluorine tag, in an 80:20 weight ratio, enabling site-specific monitoring of these crosslink-like units by19F NMR spectroscopy. Upon treatment of Pl with G2 in toluene-ds, time-resolved19F NMR revealed the gradual appearance of a sharp new fluorine signal corresponding to a small-molecule species with a chemical shift identical to that8519 PAG; SD16952.1 (103349-015PCT) of free DCPD-F (FIG. 8). Diffusion-ordered spectroscopy (DOSY) confirmed that this peak originates from a species with the same diffusion coefficient as the monomeric DCPD-F and is distinct from the polymer-bound fluorinated units. These observations indicate that under metathesis conditions, DCPD-F units embedded in the polymer undergo intramolecular ringclosing metathesis (RCM), releasing the free monomer. This behavior resembles the ceilingtemperature-driven depolymerization of polypentenamers. In effect, the cyclopentenyl -derived crosslinks within the pDCPD network undergo RCM with the catalyst, leading to “decrosslinking” and the release of soluble fragments.

[0066] To isolate the role of the main-chain alkenes, independent of cyclopentenyl contributions, polyflTDCPD) (pFbDCPD) was synthesized by polymerizing the partially hydrogenated monomer H2DCPD. Upon metathesis deconstruction, MALDI-TOF analysis showed major peaks corresponding to a cyclic H2DCPD series, and gel permeation chromatography (GPC) confirmed a substantial molecular weight reduction from 55 kDato 13.6 kDa after 20 hours (FIG. 9). These results demonstrate that chain transfer can occur along the main-chain alkenes, despite such reactivity being atypical in conventional ROMP systems. Further support came fromJH and13C NMR spectra of deconstructed pDCPD, which revealed the disappearance of most cis main-chain double bonds, consistent with chain transfer along the pFbDCPD backbone. Together, these findings confirm that the main-chain alkenes constitute a viable site for chain-transfer-driven deconstruction.

[0067] The kinetics of metathesis deconstruction in fully crosslinked pDCPD versus pFbDCPD thermosets was compared. The pFbDCPD network, synthesized via FROMP of H2DCPD with 2.5 wt% CL1, a bis-norbomene cross-linker, forms a thermoset lacking cyclopentenyl-derived crosslinks. When both samples were subjected to metathesis conditions with G2 at ambient temperature for 48 hours, the pDCPD sample fully dissolved, whereas the pFbDCPD thermoset only swelled. Notably, the swelling ratio of pFbDCPD sample under metathesis was 899%, significantly higher than the 183% swelling observed in the absence of catalyst. This enhanced swelling indicates that the main-chain alkenes do engage in chain transfer, albeit slowly, ultimately leading to complete deconstruction of the CL1 cross-linked system over approximately 10 days. The markedly slower breakdown of the pFbDCPD network confirms that the main-chain norbomenyl alkenes are intrinsically less reactive toward chain transfer than the less hindered cyclopentenyl-derived crosslink alkenes. While the latter undergo rapid ring-closing metathesis to effectively “unzip” the network, the main-chain double bonds also participate in chain transfer, forming smaller cyclooligomers accompanied by cis-to-trans isomerization.8519 PAG; SD16952.1 (103349-015PCT)

[0068] Regeneration of polymer and composite materials was also explored. Recovered oligomers were reincorporated at 20 wt% loading into neat resins and remanufactured via FROMP. Coincidentally, 20 wt% recycled oligomer loading is in good agreement with recent results demonstrating this as the upper limit for maintaining glass transition temperature, mechanical properties, and microstructure. Indeed, similar glass transition temperatures (Tgs, as indicated by the peak in tan delta, Young’s modulus, and tensile strength were observed relative to neat pDCPD materials (FIG. 10). This, coupled with the high gel fractions obtained in regenerated materials (99.7% ± 4.2%), indicates good reincorporation of recycled oligomers into DCPD resins, demonstrating promise for introducing lifecycle circularity and sustainable practices in the manufacture of these high-performance thermosets.

[0069] The ability to deconstruct more industrially relevant materials such as fiber composites and encapsulated components was investigated. A 7 cm x 7 cm portion of a 6-ply laminate (volume fraction, Vf„ X%) was deconstructed using a solution of HG2 in CPME after an initial swelling in neat CPME. The fabric plies were manually separated, washed with fresh CPME, and dried in an oven at 110 °C for 2 h to remove CPME and any residual moisture. All of the initial fiber mass was reclaimed during the deconstruction process totaling 5.98 mg with 96% of the mass retaining a woven architecture. 80% of the initial matrix mass was recovered as oligomers (3.11g). In total, 92% of the initial mass of the composite was reclaimed through metathesis deconstruction of the matrix.

[0070] The integrity of the reclaimed reinforcement was characterized by their statistical distribution of tensile strengths compared to as-received carbon fiber. Tensile tests were conducted on single carbon fiber filaments manually extracted from as-received and reclaimed carbon fiber tows following testing procedures as described in ASTM Cl 557. A precursory analysis of the mean and standard deviation of as-received and reclaimed carbon fiber showed equivalent strengths (FIG. 11). Further analysis showed the fiber tensile strengths fit the form of a Weibull distribution with high correlation with the scale parameter for as-received reinforcement nearly matching the manufacturer’s reported strength for T300 fiber (3,540 MPa). Properties derived from flaw-dominated behavior, including ceramic fiber tensile failure, are known to follow a Weibull distribution rather than a normal distribution. Furthermore, it was observed that the strength of as-received reinforcement is more broadly distributed with m=4.81 compared to m=7.04 for reclaimed reinforcement. Surprisingly, the reclaimed reinforcement had a slightly higher scale parameter, representing a greater stress at which there is a 63% probability of failure, likely due to loss of small fibers during recovery after MD. Finally, a recycled carbon fiber composite was manufactured by infusing the reclaimed reinforcement with8519 PAG; SD16952.1 (103349-015PCT) freshly prepared DCPD resin and compared it to the laminate with as-received fiber reinforcement. Characterization by dynamic mechanical analysis showed minimal to no change in modulus and glass transition temperature (FIG. 12).

[0071] To demonstrate the scalability of this composite chemical recycling technology, an additional larger laminate was manufactured using 12 plies ( I / of 58±1%) of the same carbon fiber fabric. A 200 x 140 mm portion of the 2.4 mm-thick 12-ply laminate weighing 93.79 g was also deconstructed using the HG2 / CPME solution. The recovered oligomers were dried for 5 days in vacuo resulting in a recovered oligomer mass of 20.80 g or 84% of the initial matrix mass, a slightly higher recovery efficiency than the small-scale experiments. The 3.1 g gained by the reinforcement, which can in principle be recovered through optimization of the deconstruction procedures, accounts for 12% of the initial matrix mass resulting in approximately 4% of the initial matrix mass lost due to washing and handling. The large, reclaimed carbon fiber fabric plies were dried for 2 days in vacuo to fully remove CPME and moisture while minimizing oxidation of any residual degraded material. In total, the recovered fabric plies weighed 72. 10 g, a 4% increase over the calculated initial mass. Overall, 99% of the initial mass of the laminate was recovered as reclaimed carbon fiber and matrix oligomers.

[0072] In addition to thickness-dependence, there was variation in the deconstruction quality in the plane of the laminate. Visible residual degraded material was seen near the center of the bottom plies as well as a visibly clear region around the edge of the contaminated plies. FTIR scans near the center and edge of the bottom ply reveal starkly different DCPD signatures, indicating less residual degraded polymer is present near the edge of the ply. The variation in deconstruction quality through the thickness and in the plane of the laminate suggest diffusion of the catalyst into the laminate plays a critical role and should be a principal consideration for further scaling and optimization of this chemical recycling method.

[0073] As an applied example, a simple electronic circuit board was embedded in DCPD (manufactured by FROMP) and recovered via MD (G1 (2 mg / mL) in toluene over the course of ~64 hours (FIG. 13). After MD, the device was still operational though minor damage to rubber components (i.e., buttons) was observed likely due to the pDCPD swelling and solvent effects of toluene.

[0074] A variety of commercial pDCPD-based materials and glass fiber composite samples were obtained. (Small pieces were cut from the samples (~0.5 g to 5 g) and were deconstructed using HG2 in toluene (0.67 mol% catalyst loading) at 80°C over several days. All non-composite samples were seen to deconstruct within approximately 24-48 hours and oligomers precipitated in cold methanol resulting in recoveries ranging from >84% and 47-79%8519 PAG; SD16952.1 (103349-015PCT) for the non-composite and composite samples, respectively. Total recoveries including oxidized and other material fillers were generally >90%. Samples containing glass fibers or sheets were able to be deconstructed and fiber isolated with a total material recovery yield of >90%. These results show promising application of MD beyond the scope of lab-scale experiments.

[0075] Thermoset deconstruction remains an important aim for scientists with pDCPD as a particularly tough material. The present inventors have reported a scalable, metathesis deconstruction (MD) chemical recycling strategy for pDCPD thermosets, composites, and encapsulated electronics that utilizes commercially available HG2 ruthenium catalyst in CPME as a ‘green’ solvent in an exemplary process. Process optimization and mechanistic studies reveal that catalytic fragmentation proceeds through both ring-closing metathesis and chain transfer with efficacy affected by solvent, catalyst, temperature, and atmosphere thereby allowing for efficient breakdown and recovery of a range of pDCPD containing materials.

[0076] Under optimized conditions quantitative deconstruction was achieved with recoveries routinely exceeding 90% of original starting material for lab-manufactured and commercial pDCPD samples. Additionally, reclaimed carbon and glass fiber composites could be deconstructed, and carbon fibers were shown to maintain original mechanical integrity upon recovery. Reincorporation of up to 20 wt% pDCPD fragments into fresh DCPD resin produced regenerated materials with comparable thermomechanical properties, representing a method for closing the loop on pDCPD materials. As a final demonstration of scalability, a life-cycle analysis and techno-economic analysis revealed that net environmental and economic benefits versus landfilling can be readily achieved with the reported method.

[0077] This disclosure establishes metathesis deconstruction as a practical route to circularity for high-performance thermosets by enabling clean separation and high-value recovery of both polymer and composite materials. The present results demonstrate a viable, lower-impact alternative to disposal and incineration and a realistic path toward closed-loop manufacturing for pDCPD-based systems. A significant improvement is therefore provided by the present disclosure.

[0078] This disclosure further encompasses the following aspects.

[0079] Aspect 1: A method for deconstruction of an olefinic thermoset, the method comprising: contacting the olefinic thermoset; an organic solvent; and a ruthenium metathesis catalyst; under conditions effective to provide a deconstructed olefinic polymer composition; wherein the olefinic thermoset comprises less than 50 mole percent of repeat units derived from cyclopentene.

[0080] Aspect 2: The method of aspect 1, wherein the olefinic thermoset comprises8519 PAG; SD16952.1 (103349-015PCT) poly dicyclopentadiene, a copolymer thereof, or a derivative thereof.

[0081] Aspect 3: The method of aspect 1 or 2, wherein the organic solvent comprises benzene, chlorobenzene, toluene, xylene, tetrahydrofuran, cyclopentyl methyl ether, or a derivative thereof.

[0082] Aspect 4: The method of any of aspects 1 to 3, wherein the organic solvent comprises cyclopentyl methyl ether or a derivative thereof.

[0083] Aspect 5: The method of any of aspects 1 to 3, wherein the ruthenium metathesis catalyst comprises a first-generation Grubbs catalyst, second-generation Grubbs catalyst, third- generation Grubbs catalyst, a nitro-Grela-h catalyst, or a Hoveyda-Grubbs catalyst.

[0084] Aspect 6: The method of any of aspects 1 to 4, wherein the ruthenium metathesis catalyst comprises a second generation Hoveyda-Grubbs catalyst.

[0085] Aspect 7: The method of any of aspects 1 to 6, wherein the deconstructed polymer composition comprises a linear oligomer derived from the olefinic thermoset, a cyclic oligomer derived from the olefinic thermoset, a cyclic olefin monomer derived from the olefinic thermoset, or a combination thereof.

[0086] Aspect 8: The method of any of aspects 1 to 7, wherein the deconstructed olefinic polymer composition is soluble in the organic solvent.

[0087] Aspect 9: The method of any of aspects 1 to 8, wherein the conditions effective to provide the deconstructed olefinic polymer composition comprise a temperature of 20 to 100°C; and a time of 30 minutes to 72 hours.

[0088] Aspect 10: The method of any of aspects 1 to 9, wherein the conditions effective to provide the deconstructed olefinic polymer composition comprise a temperature of 40 to 100°C; and a time of 1 to 50 hours.

[0089] Aspect 11: The method of any of aspects 1 to 10, wherein the contacting is under an inert atmosphere.

[0090] Aspect 12: The method of any of aspects 1 to 10, wherein the contacting is under ambient conditions in the presence of oxygen.

[0091] Aspect 13: The method of any of aspects 1 to 12, wherein the olefinic thermoset is present in an olefin repeat unit concentration of 1 millimoles per liter of organic solvent to 2 moles per liter of organic solvent, preferably 150 to 300 millimoles per liter of organic solvent.

[0092] Aspect 14: The method of any of aspects 1 to 13, wherein the ruthenium metathesis catalyst is present in an amount effective to provide a concentration of 0.001 to 5 mole percent, based on total moles of olefin repeat units, preferably 0.5 to 0.75 mole percent, based on total moles of olefin repeat units.8519 PAG; SD16952.1 (103349-015PCT)

[0093] Aspect 15: The method of aspect 1, comprising: contacting an olefinic thermoset comprising polydicyclopentadiene or a derivative thereof; an organic solvent comprising cyclopentyl methyl ether; and a ruthenium metathesis catalyst comprising a Hoveyda-Grubbs catalyst; at a temperature of 20 to 100°C and for a time of 30 minutes to 72 hours; wherein the olefinic thermoset is present in an olefin repeat unit concentration of 150 to 300 millimoles per liter of organic solvent; and the ruthenium metathesis catalyst is present in an amount effective to provide a concentration of 0.5 to 0.75 mole percent, based on total moles of olefin repeat units.

[0094] Aspect 16: The method of any of aspects 1 to 15, wherein the deconstructed olefinic polymer composition retains at least 85 weight percent, preferably at least 90 weight percent of an initial weight of the olefinic thermoset.

[0095] Aspect 17: The method of any of aspects 1 to 16, further comprising recovering the deconstructed olefinic polymer composition.

[0096] Aspect 18: The method of aspect 17, wherein recovering the deconstructed olefinic polymer composition comprises contacting the deconstructed olefinic polymer composition with a polar solvent, and isolating the precipitated deconstructed olefinic polymer composition.

[0097] Aspect 19: The method of aspect 17 or 18, wherein the deconstructed olefinic polymer composition is recovered in an amount of at least 75 weight percent, preferably at least 80 weight percent, based on an initial weight of the olefinic thermoset.

[0098] Aspect 20: The method of any of aspects 1 to 19, wherein the olefinic thermoset further comprises an additive, preferably a reinforcing filler or a reinforcing layer.

[0099] Aspect 21: The method of any of aspects 1 to 19, wherein an article is encapsulated by the olefinic thermoset, and the method further comprises recovering the article, preferably wherein the article is an electronic component.

[0100] Aspect 22: A method for the manufacture of a recycled thermoset, the method comprising: polymerizing a deconstructed olefinic polymer composition obtained by the method of any of aspects 1 to 21 and, optionally, a virgin cyclic olefin monomer; in the presence of an olefin metathesis catalyst to provide the recycled thermoset.

[0101] Aspect 23: The method of aspect 22, wherein the polymerizing is in the absence of a solvent.

[0102] Aspect 24: The method of aspect 22 or 23, wherein the recycled thermoset is derived from 1 to 99 weight percent, preferably 70 to 99 weight percent of the virgin cyclic olefin monomer; and 1 to 99 weight percent, preferably 1 to 30 weight percent of the8519 PAG; SD16952.1 (103349-015PCT) deconstructed olefinic polymer composition, wherein weight percent is based on the total weight of the recycled thermoset.

[0103] Aspect 25: The method of any of claims 22 to 24, wherein the recycled thermoset has a Young’s modulus that is within 20%, preferably within 10% of a Young’s modulus for a corresponding virgin thermoset; and an ultimate tensile strength that is within 20%, preferably within 10% of an ultimate tensile strength for a corresponding virgin thermoset, determined according to ASTM D638 Type V.

[0104] Aspect 26: A recycled thermoset made by the method of any of aspects 22 to 25.

[0105] Aspect 27: A recycled thermoset derived from a curable composition comprising a virgin cyclic olefin monomer; and a deconstructed olefinic polymer composition obtained by the method of any of aspects 1 to 21 and comprising a macrocyclic compound; wherein the recycled thermoset comprises the macrocyclic compound or a cyclic derivative thereof.

[0106] The compositions, methods, and articles can alternatively comprise, consist of, or consist essentially of, any appropriate materials, steps, or components herein disclosed. The compositions, methods, and articles can additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any materials (or species), steps, or components, that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles.

[0107] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. “Combinations” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms “first,” “second,” and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms “a” and “an” and “the” do not denote a limitation of quantity, and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and / or” unless clearly stated otherwise. Reference throughout the specification to “an aspect” means that a particular element described in connection with the aspect is included in at least one aspect described herein, and may or may not be present in other aspects. The term “combination thereof’ as used herein includes one or more of the listed elements, and is open, allowing the presence of one or more like elements not named. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various aspects.

[0108] Unless specified to the contrary herein, all test standards are the most recent standard in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.8519 PAG; SD16952.1 (103349-015PCT)

[0109] Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this application belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

[0110] Compounds are described using standard nomenclature. For example, any position not substituted by any indicated group is understood to have its valency filled by a bond as indicated, or a hydrogen atom. A dash that is not between two letters or symbols is used to indicate a point of attachment for a substituent. For example, -CHO is attached through carbon of the carbonyl group.

[0111] Unless substituents are otherwise specifically indicated, each of the foregoing groups can be unsubstituted or substituted, provided that the substitution does not significantly adversely affect synthesis, stability, or use of the compound. “Substituted” means that the compound, group, or atom is substituted with at least one (e.g., 1, 2, 3, or 4) substituents instead of hydrogen, where each substituent is independently nitro (-NO2), cyano (-CN), hydroxy (-OH), halogen, thiol (-SH), thiocyano (-SCN), C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C1-6 haloalkyl, C1-9 alkoxy, C1-6 haloalkoxy, C3-12 cycloalkyl, C5-I8 cycloalkenyl, C6-12 aryl, C7-13 arylalkylene (e.g., benzyl), C7-12 alkylarylene (e.g, toluyl), C4-12 heterocycloalkyl, C3-12 heteroaryl, C1-6 alkyl sulfonyl (-S(=O)2-alkyl), C6-12 arylsulfonyl (-S(=O)2-aryl), or tosyl (CH3C6H4SO2-), provided that the substituted atom’s normal valence is not exceeded, and that the substitution does not significantly adversely affect the manufacture, stability, or desired property of the compound. When a compound is substituted, the indicated number of carbon atoms is the total number of carbon atoms in the compound or group, including those of any substituents.

[0112] While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.

Claims

8519 PAG; SD16952.1 (103349-015PCT)CLAIMS1. A method for deconstruction of an olefinic thermoset, the method comprising: contacting the olefinic thermoset; an organic solvent; and a ruthenium metathesis catalyst; under conditions effective to provide a deconstructed olefinic polymer composition; wherein the olefinic thermoset comprises less than 50 mole percent of repeat units derived from cyclopentene.

2. The method of claim 1, wherein the olefinic thermoset comprises polydicyclopentadiene, a copolymer thereof, or a derivative thereof.

3. The method of claim 1, wherein the organic solvent comprises benzene, chlorobenzene, toluene, xylene, tetrahydrofuran, cyclopentyl methyl ether, or a derivative thereof, preferably cyclopentyl methyl ether or a derivative thereof.

4. The method of claim 1, wherein the ruthenium metathesis catalyst comprises a first- generation Grubbs catalyst, second-generation Grubbs catalyst, third-generation Grubbs catalyst, a nitro-Grela-h catalyst, or a Hoveyda-Grubbs catalyst, preferably a second generation Hoveyda- Grubbs catalyst.

5. The method of claim 1, wherein the deconstructed polymer composition comprises a linear oligomer derived from the olefinic thermoset, a cyclic oligomer derived from the olefinic thermoset, a cyclic olefin monomer derived from the olefinic thermoset, or a combination thereof.

6. The method of claim 1, wherein the deconstructed olefinic polymer composition is soluble in the organic solvent.

7. The method of claim 1, wherein the conditions effective to provide the deconstructed olefinic polymer composition comprise a temperature of 20 to 100°C; and8519 PAG; SD16952.1 (103349-015PCT) a time of 30 minutes to 72 hours.

8. The method of claim 1, wherein the contacting is under an inert atmosphere.

9. The method of claim 1, wherein the contacting is under ambient conditions in the presence of oxygen.

10. The method of claim 1, wherein the olefinic thermoset is present in an olefin repeat unit concentration of 1 millimole per liter of organic solvent to 2 moles per liter of organic solvent, preferably 150 to 300 millimoles per liter of organic solvent; and the ruthenium metathesis catalyst is present in an amount effective to provide a concentration of 0.001 to 5 mole percent, based on total moles of olefin repeat units, preferably 0.5 to 0.75 mole percent, based on total moles of olefin repeat units.

11. The method of claim 1, comprising: contacting an olefinic thermoset comprising polydicyclopentadiene or a derivative thereof; an organic solvent comprising cyclopentyl methyl ether; and a ruthenium metathesis catalyst comprising a Hoveyda-Grubbs catalyst; at a temperature of 20 to 100°C and for a time of 30 minutes to 72 hours; wherein the olefinic thermoset is present in an olefin repeat unit concentration of 150 to300 millimoles per liter of organic solvent; and the ruthenium metathesis catalyst is present in an amount effective to provide a concentration of 0.5 to 0.75 mole percent, based on total moles of olefin repeat units.

12. The method of claim 1, wherein the deconstructed olefinic polymer composition retains at least 85 weight percent, preferably at least 90 weight percent of an initial weight of the olefinic thermoset.

13. The method of claim 1, further comprising recovering the deconstructed olefinic polymer composition, wherein recovering the deconstructed olefinic polymer composition comprises contacting the deconstructed olefinic polymer composition with a polar solvent, and isolating the8519 PAG; SD16952.1(103349-015PCT) precipitated deconstructed olefinic polymer composition, preferably wherein the deconstructed olefinic polymer composition is recovered in an amount of at least 75 weight percent, preferably at least 80 weight percent, based on an initial weight of the olefinic thermoset.

14. The method of claim 1, wherein the olefinic thermoset further comprises an additive, preferably a reinforcing filler or a reinforcing layer.

15. The method of claim 1, wherein an article is encapsulated by the olefinic thermoset, and the method further comprises recovering the article, preferably wherein the article is an electronic component.

16. A method for the manufacture of a recycled thermoset, the method comprising: polymerizing a deconstructed olefinic polymer composition obtained by the method of claim 1; and optionally, a virgin cyclic olefin monomer; in the presence of an olefin metathesis catalyst to provide the recycled thermoset, optionally, wherein the polymerizing is in the absence of a solvent.

17. The method of claim 16, wherein the recycled thermoset is derived from1 to 99 weight percent, preferably 70 to 99 weight percent of the virgin cyclic olefin monomer; and1 to 99 weight percent, preferably 1 to 30 weight percent of the deconstructed olefinic polymer composition, wherein weight percent is based on the total weight of the recycled thermoset.

18. The method of claim 16, wherein the recycled thermoset has a Young’s modulus that is within 20%, preferably within 10% of a Young’s modulus for a corresponding virgin thermoset; and an ultimate tensile strength that is within 20%, preferably within 10% of an ultimate tensile strength for a corresponding virgin thermoset, determined according to ASTM D638 Type V.

19. A recycled thermoset made by the method of claim 16.8519 PAG; SD16952.1 (103349-015PCT)20. A recycled thermoset derived from a curable composition comprising a virgin cyclic olefin monomer; and a deconstructed olefinic polymer composition obtained by the method of claim 1 and comprising a macrocyclic compound; wherein the recycled thermoset comprises the macrocyclic compound or a cyclic derivative thereof.

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