Polycyanurate formulations featuring soft-segment incorporation and methods of making and using same

Abstract

A curable composition comprising a hydroxyl or cyanurate-functional, hyperbranched polycyanurate (PCN) prepolymer obtainable by reversible nucleophilic aromatic substitution (SNAr) between a tri-alkoxy and / or tri-aryloxy 1,3,5-triazine and an alcohol component selected from mono-ols, diols, and polyols. The hyperbranched PCN prepolymer provides low viscosity at high functional-group density and programmable end groups to control molecular weight, functionality, and crosslink density. In particular, end-group programmability enables orthogonal build-outs: hydroxyl-terminated oligomers are further polymerized with alkoxy / aryloxy triazines to yield PCN thermoset networks, while alkoxy / aryloxy triazine-terminated oligomers are subsequently polymerized with polyols or other multifunctional nucleophiles to provide the complementary construction of a cyanurate-rich network.

Description

Docket No. ROCT.P2007WO / 00651221Polycyanurate Formulations Featuring Soft-Segment Incorporation and Methods of Making and Using SameRELATED APPLICATION

[0001] This application claims priority to US Provisional Application No. 63 / 705,413 filed on October 9, 2024, the content of which is incorporated herein by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] The present disclosure relates to polycyanurate (PCN) thermosets. More particularly, it concerns soft-segment-modified polycyanurate compositions, precursors and catalysts therefor, methods of making such compositions by curing, and / or co-curing, and articles and coatings derived therefrom that exhibit enhanced flexibility and toughness while retaining the characteristic high thermal stability, low dielectric constant, low moisture uptake, and radiation resistance of triazine-rich networks.BACKGROUND

[0003] Polycyanurates (PCNs) are the thermosets typically formed from cyanate ester resins through homo-trimerization. PCNs are among the most advanced high-performance thermosetting systems and compete directly with epoxies and bismaleimides (BMI) across aerospace, microelectronics, and cryogenic applications. Their performance derives from polycyanurate networks containing triazine rings, which confer balanced dipoles, low polarity, and minimal hydrogen bonding — attributes correlated with low dielectric constant, low dissipation factor, and low water absorption relative to epoxy or BMI matrices. Triazine-rich networks also display exceptional radiation tolerance and mechanical and electrical stability at cryogenic temperature.

[0004] Despite these advantages, conventional aryl-cyanate formulations produced by homo-trimerization are brittle, costly, and compositionally constrained to aryl cyanate monomers. To achieve acceptable fracture resistance, current practice frequently blends PCNs with epoxies or inorganic fillers, trading off dielectric performance, outgassing, and / or heat resistance.SUMMARY

[0005] The present invention provides a class of polycyanurate (PCN) prepolymers and methods of using them to form cyanurate-rich thermoset networks with improved processability and toughness. The prepolymers are prepared by reversible nucleophilicDocket No. ROCT.P2007WO / 00651221 aromatic substitution (S\Ar) on 1,3,5-triazine electrophiles and feature hyperbranched architectures that deliver low viscosity at high functional-group density.

[0006] In one aspect, a hydroxyl-functional PCN prepolymer is formed by reversible S\Ar between a trialkoxy and / or triaryloxy triazine (e.g., 2, 4, 6-triethoxy- 1,3,5-triazine) and one or more alcohols selected from mono-ols, diols, and polyols, including aliphatic and aromatic (phenolic) alcohols with at least one multivalent alcohol to introduce branching. The resulting PCN polyol bears a plurality of reactive hydroxyl groups (aliphatic and / or phenolic), enabling subsequent network formation and / or chemical derivatization. Owing to its hyperbranched topology, it exhibits minimal chain entanglement and smooth, low-viscosity flow in solution or melt.

[0007] In another aspect, the stoichiometry and sequence of the S\Ar reaction are controlled such that the growing PCN oligomers possess selected terminal groups — either hydroxyl-terminated or alkoxy / aryloxy triazine-terminated.

[0008] In certain embodiments, hydroxyl-terminated oligomers are subsequently polymerized with alkoxy / aryloxy triazines and / or other cyanate-forming monomers to yield PCN thermoset networks. Alkoxy / aryloxy-terminated oligomers are subsequently polymerized with polyols or other multifunctional nucleophiles to provide the complementary build-out to a cyanurate-rich network. This end-group programmability enables precise control over molecular weight, functionality, viscosity, and crosslink density during cure.

[0009] In another aspect, the PCN polyol serves as a versatile intermediate for creating hybrid thermosets:

[0010] PCN-polyurethane (PCN-PU) via reaction with isocyanates, integrating urethane segments with cyanurate domains;

[0011] PCN-epoxy (PCN-EP) by directly reacting PCN polyols with epoxy monomers or converting the PCN polyol to a polyepoxide prepolymer (e.g., via etherification with epichlorohydrin) and curing alone or directly co-curing with additional epoxy monomers; and

[0012] PCN-polyester (PCN-PE) by polyesterification with diacids / diesters / anhydrides / acid chlorides and / or ring-opening polymerization of lactones, followed by co-cure to maintain high triazine content.

[0013] In another aspect, the hydroxyl groups of the PCN polyol are capped (e.g., etherified or esterified) to form substantially nonreactive, PCN-compatible oligomeric plasticizers. These additives are blended with aryl cyanate esters during trimerization or S\Ar- based curing to reduce modulus and residual stress and enhance toughness without materially altering established industrial workflows.Docket No. ROCT.P2007WO / 00651221

[0014] The platform technology disclosed herein addresses key industry challenges by providing: (1) Excellent Tunability: The vast choice of alcohols allows precise control over molecular weight, viscosity, and cross-link density. (2) Superior Processability: The hyperbranched architecture ensures low viscosity for easy processing. (3) Material Versatility: Enables the creation of a wide range of materials from a single prepolymer platform, including pure PCNs, PCN-PU hybrids, PCN-EP hybrids, PCN-PE hybrids, and performance additives. (4) Enhanced Properties: The resulting thermoset networks are engineered to exhibit a superior combination of properties, including high thermal stability, enhanced toughness, reduced deformation during extreme thermal cycling, and excellent dielectric characteristics, making them ideal for applications in aerospace, electronics, and advanced insulation.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 shows formation of hydroxyl-functional PCN prepolymers (aliphatic and / or phenolic) and their utilization to construct PCN networks, hybrid PCN-polyurethane (PCN-PU), PCN-polyester (PCN-PE), and PCN-epoxy (PCN-EP) systems, and preparation of capped, nonreactive oligomeric plasticizers.

[0016] FIG. 2 shows a two-stage preparation of PCN networks in which a soluble, melt- flowable oligomeric polycyanurate is first generated with reactive alkoxy-triazine end groups, and is then chain-extended / crosslinked via further SNAr to afford a PCN thermoset network.

[0017] Fig. 3 shows representative examples of alcohols, curable co-monomers, and capping reagents.

[0018] Fig 4 shows a kinetic SNAr study of 2,4,6-triethoxy-l,3,5-triazine with n- butanol.

[0019] (A) Reaction scheme. Model exchange between 2,4,6-triethoxy-l,3,5-triazine and n-butanol (nBuOH) under a base catalysis. Successive substitutions give mono-, di-, and tri-butoxy triazines; ethanol is removed during the run.

[0020] (B) Relative conversion profiles. Time-dependent “relative” 2,4,6-triethoxy-1,3,5-triazine for different bases at identical loading / conditions. l,5,7-triazabicyclo[4.4.0]dec- 5-ene (TBD) ~ KOtBu ~ NaOtBu show the fastest apparent rates; 1,8- Diazabicyclo[5.4.0]undec-7-ene (DBU) and K2CO3 are slower and plateau before full conversion. A small background reaction is observed at room temperature, with accelerated progress on heating.DocketNo. ROCT.P2007WO / 00651221

[0021] Fig. 5 shows neat PCN film (left): Solvent-free, bubble-free PCN film cast from PCN polyol prepolymer and cured under staged thermal profile; exhibits high optical clarity and uniform thickness.

[0022] PCN / Glass-fiber laminate (right): PCN matrix impregnated into a woven glassfiber mat and cured to form a transparent to translucent composite with complete wet-out, no visible voids, and good fiber consolidation.

[0023] Fig. 6 shows formation and appearance of a PCN-Epoxy (PCN-EP) hybrid.

[0024] Shown is a hard, transparent bar obtained from a cyanurate-epoxy hybrid network. The PCN-EP hybrid is prepared by reacting the hydroxyl-functional PCN prepolymer prepared from 2,4,6-triethoxy-l,3,5-triazine and 1,4-butanediol with Bisphenol A diglycidyl ether.

[0025] Fig. 7 shows representative tensile stress-strain curves of 1,6-hexanediol-based PCN films prepared using different base catalyst amounts.

[0026] Fig. 8 shows 1,6-Hexanediol-based PCN films are transparent to frequencies ranging from 30 kHz up to 26.5 GHz. When compared to other common plastics such as PET, PTFE, and LDPE, — normalized for thickness — the PCN films exhibited lower intensity across the entire frequency range.

[0027] Fig. 9 shows cryogenic thermal-cycling performance of 1,6-hexanediol and 1,12-dodecanediol-based PCN films.

[0028] Specimens were bent at room temperature (RT), immersed in liquid nitrogen (77 K) for 8 h, rewarmed to RT, and tensile-tested; the sequence was repeated for two cycles. Films showed minimal shape change and negligible variation in tensile properties after two cycles. In a separate series of five consecutive cycles — with the last three immersions shortened to 10 min — each film returned to a flat, original geometry on warming, evidencing excellent thermal stability, chemical resistance, and reversible shape recovery under extreme thermal shock.

[0029] Fig. 10 shows tensile performance after cryogenic treatment.

[0030] Left: Tensile properties of a 1 , 12-dodecanediol-based PCN film after the second cryogenic cycle; subsequent 10 fatigue cycles under strain produced no measurable change.

[0031] Right: Tensile stress-strain curves of 1,12-dodecanediol-based PCN film after six consecutive RT«->77 K thermal cycles, showing negligible change in modulus, strength, and elongation relative to pre-cycle values.

[0032] Fig. 11 shows lamination of PCN films using diol / TBD interlayer. Two 1,6-hexanediol-based PCN films were stacked with an interlayer solution of a 1,6-Docket No. ROCT.P2007WO / 00651221 hexanediol containing TBD (10 mol% relative to total hydroxyl groups). The stack was heat- pressed at 120 °C (under light pressure) for a fixed dwell, allowing base-catalyzed S\Ar reaction at the film surfaces. A fully laminated panel with no visible interface by optical inspection was obtained. The bondline is optically continuous and free of voids, indicating complete interdiffusion and bonding across the interface.DETAILED DESCRIPTIONDefinitions

[0033] As used herein, “polycyanurate” (PCN) means a polymer network comprising trialkoxy / aryloxy 1,3,5-triazine (“cyanurate”) rings that are covalently integrated into the polymer backbone; in this specification, PCNs are formed via nucleophilic aromatic substitution (SNAr) on triazine electrophiles (no cyanate-ester cyclotrimerization is required).

[0034] “SNAr” refers to nucleophilic aromatic substitution on a triazine bearing alkoxy and / or aryloxy leaving groups, typically under basic conditions, with displacement of the corresponding alcohol.

[0035] ‘ ‘PCN polyol” (also “hydroxyl-functional PCN prepolymer”) denotes a hydroxyl-functional, hyperbranched PCN oligomer obtained by S\Ar between a trialkoxy / aryloxy triazine (e.g., 2, 4, 6-triethoxy- 1,3,5-triazine, ) and an alcohol component (mono-ols, diols, and / or polyols) including aliphatic and phenolic alcohols.

[0036] “PCN-PU,” “PCN-EP,” and “PCN-PE” respectively denote PCN-polyurethane, PCN-epoxy, and PCN-polyester hybrids.

[0037] “Cyanurate-rich” describes compositions that, after cure, comprise a significant cyanurate functionality, e.g., 30-70 mol%, 70-95 mol% of the total curable functionality in the cured network is cyanurate-forming (triazine) content.

[0038] The disclosed platform exploits (i) the versatility of the triazine S\Ar exchange and (ii) the broad availability of alcohol monomers (aliphatic, cycloaliphatic, aromatic; monools, diols, polyols). This scheme enables rapid architectural tuning of PCN prepolymers and their integration into hybrid networks while preserving hallmark PCN attributes (low dielectric constant / loss, low moisture uptake, radiation tolerance, cryogenic stability).

[0039] A practical challenge of direct S\Ar in coatings or bulk articles is the evolution of small-molecule alcohol byproducts (e.g., methanol, ethanol) inherent to the exchange. These volatiles can form bubbles and voids during cure. To mitigate this, the invention adopts a prepolymer strategy: PCN-prepolymer is first synthesized under controlled conditions, the volatile alcohol byproducts are removed, and the resulting low-viscosity PCN prepolymer isDocket No. ROCT.P2007WO / 00651221 then used as a building block in downstream polymerization to form PCN thermoset films and coating, as well as hybridizations (PU, epoxy, polyester) or as a tailored plasticizer.

[0040] Various aspects of this disclosure are further illustrated by the following items:

[0041] Item 1. A polycyanurate prepolymer, comprising a plurality of 1,3,5-triazine (“cyanurate”) nodes covalently linked through — O — R — O — linkage, the polycyanurate prepolymer having a plurality of terminal groups, wherein the terminal group is (a) hydroxyl groups (hydroxyl-terminated polycyanurate prepolymer, “PCN polyol”), or (b) alkoxy and / or aryloxy triazine groups (triazine-terminated polycyanurate prepolymer), wherein R is

[0042] (i) C1-C30 alkylene, C3-C20 cycloalkylene, C6-C20 arylene, or C7-C20 aralkylene, each optionally substituted with Ci-Ce alkyl, halo, cyano, or Ci-Ce alkoxy;

[0043] (ii) heteroatom-interrupted groups in which the alkylene or aralkylene backbone is optionally interrupted by — O — , — S — , — NR' — , — CO — , — COO — , — OCO — , — SO2 — , carbonate, or urethane (carbamate) linkages;

[0044] (iii) poly(alkylene oxide) segments of the formula — (CH2CHR'O)n— where R' = H or C1-C4 alkyl and n = 2-500 (including PEG, PPG, PTMEG);

[0045] (iv) aromatic diol residues including phenylene-, biphenyl-, or bisphenol-type residues (e.g., resorcinol, hydroquinone, bisphenol structures) optionally bearing alkyl, halo, alkoxy, or perfluoroalkyl substituents;

[0046] (v) siloxane-containing segments of the formula — [Si(R")2 — O]m— where R" is Ci— Ce alkyl or phenyl and m = 2-500; or

[0047] (vi) combinations and copolymeric sequences of any of (i)-(v);

[0048] Item 2. The polycyanurate prepolymer of Item 1, wherein the terminal groups are the same within same prepolymer.

[0049] Item 3. The polycyanurate prepolymer of any of Items 1-2, obtained by reversible nucleophilic aromatic substitution (S\Ar) between a triazine compound having three alkoxy and / or aryloxy leaving groups and an alcohol component comprising one or more of mono-ols, diols, and polyols, the prepolymer having a hyperbranched architecture.

[0050] Item 4. A composition comprising the polycyanurate prepolymer of any of Items 1-3, wherein the composition is curable.

[0051] Item 5. The composition of Item 4, obtained by reacting the prepolymer obtained in claim 3 with one or more co-reactants selected from: alcohols, cyanurates, isocyanates, epoxy monomers or prepolymers, and ester-forming reagents comprising diacids, diesters, anhydrides, acid chlorides, and lactones; wherein the composition is curable to aDocket No. ROCT.P2007WO / 00651221 cyanurate-rich thermoset network, and wherein the prepolymer provides low viscosity at high functional-group density suitable for high-solids processing.

[0052] Item 6. The polycyanurate prepolymer of any preceding Items, wherein the 1,3,5-triazine node comprises 2,4,6-alkoxy-l,3,5-triazine or 2,4,6-tri(aryloxy)-l,3,5-triazine.

[0053] Item 7. The polycyanurate prepolymer of any of any preceding Items, wherein the alcohol component comprises at least one multivalent alcohol selected from aliphatic and / or aromatic (phenolic) diols and polyols to introduce branching.

[0054] Item 8. The polycyanurate prepolymer of any preceding Items, wherein the prepolymer has an OH value of about 50-600 mg KOH / g and a solution viscosity at 60-80 wt% solids of about 100-2,000 cP at 25 °C.

[0055] Item 9. The polycyanurate prepolymer of any preceding Items, wherein the S\ Ar stoichiometry and sequence are selected to provide hydroxyl-terminated prepolymer end groups.

[0056] Item 10. The polycyanurate prepolymer of any preceding Items, further comprising alkoxy and / or aryloxy triazines as co-reactants such that hydroxyl-terminated oligomers are polymerized therewith to yield a polycyanurate thermoset.

[0057] Item 11. The polycyanurate prepolymer of any preceding Items, wherein the S\ Ar stoichiometry and sequence are selected to provide alkoxy- or aryloxy-triazine terminated oligomers.

[0058] Item 12. The polycyanurate prepolymer of any preceding Items, further comprising polyols or other multifunctional nucleophiles as co-reactants, wherein alkoxy - / aryloxy-terminated oligomers are polymerized therewith to yield a cyanurate-rich network.

[0059] Item 13. The composition of any preceding Items, wherein the co-reactant set comprises an isocyanate, and curing yields a PCN-polyurethane (PCN-PU) hybrid having urethane soft segments integrated with cyanurate domains.

[0060] Item 14. The polycyanurate prepolymer of any preceding Items, wherein the prepolymer is etherified with epichlorohydrin to form a polyepoxide.

[0061] Item 15. The composition of any preceding Items, wherein the one or more coreactants comprise an epoxy curing agent and optionally additional epoxy monomers, thereby yielding a PCN-epoxy (PCN-EP) hybrid on cure.

[0062] Item 16. The composition of any preceding Items, wherein the one or more coreactants comprise one or more ester-forming reagents selected from diacids, diesters, anhydrides, acid chlorides, and lactones, thereby yielding a PCN-polyester (PCN-PE) hybrid on cure.Docket No. ROCT.P2007WO / 00651221

[0063] Item 17. The polycyanurate prepolymer of any preceding Items, wherein at least a portion of the terminal hydroxyl groups of the prepolymer are capped by ether, ester, or carbamate (urethane) formation to provide a substantially non-reactive, PCN-compatible plasticizer.

[0064] Item 18. The polycyanurate prepolymer of any preceding Items, wherein the capped prepolymer is present at about 0.5-15 wt% of the total composition and is blended with aryl cyanate esters to reduce modulus and residual stress and increase toughness during trimerization.

[0065] Item 19. The composition any preceding Items, wherein the composition further comprises a cyanurate-formation catalyst selected from the group consisting of 1,5,7- triazabicyclo[4.4.0]dec-5-ene (TBD), l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), potassium carbonate (K2CO3), potassium tert-butoxide (KOtBu), and sodium tert-butoxide (NaOtBu), disodium bisphenol A, and combination thereof, and wherein the composition is curable under a staged thermal profile comprising holds between about 100-230 °C, or between about 100 - 140 °C.

[0066] Item 20. The composition of any preceding Items, wherein volatile byproducts generated during prepolymer preparation are removed prior to use of the composition, thereby enabling bubble-free films at >60 wt% solids.

[0067] Item 21. The composition of any preceding Items, wherein the cured thermoset network exhibits at least one of the following properties: dielectric constant <3.2 (1 MHz- 10 GHz), moisture uptake <1.5 wt%, low outgassing compatible with vacuum applications, or improved tensile toughness relative to neat aryl polycyanurates.

[0068] Item 22. The polycyanurate prepolymer of any preceding Items, wherein the prepolymer exhibits a hyperbranched topology that minimizes chain entanglement relative to linear polymers at comparable functionality.

[0069] Item 23. The composition of any preceding Items, wherein the composition is curable to provide coatings, encapsulants, laminates, adhesive films, or insulation.

[0070] Item 24. The composition of any preceding Items, wherein the cyanurate-rich fraction constitutes 30-70 mol% or 70-95 mol% of total curable functionality in the cured network.

[0071] Item 25. The polycyanurate prepolymer of any preceding Items, wherein the alcohol component comprises a mixture of aliphatic and aromatic alcohols to tune modulus and toughness, and the triazine leaving group set (alkoxy vs. aryloxy) is selected to control S\Ar kinetics.Docket No. ROCT.P2007WO / 00651221

[0072] Item 26. The composition of any preceding Items, wherein the composition excludes added solvents during final cure and achieves uniform, defect-free films by virtue of the low viscosity of the prepolymer.

[0073] Item 27. The composition of any preceding Items, wherein the cured network is configured for aerospace, electronics, RF / antenna covers, protective coatings, or advanced insulation applications requiring thermal stability, dielectric performance, low moisture uptake, cryogenic cycling, and toughness.

[0074] Item 28. The composition of any preceding Items, wherein the cured network comprises reversibly exchangeable triazine-alkoxy and / or triazine-aryloxy linkages configured to undergo base-catalyzed exchange, thereby providing repairability including stress relaxation, crack healing, and reshaping without loss of cyanurate content.

[0075] Item 29. The composition of any preceding Items, wherein the composition further comprises a latent or active base catalyst selected from a carbonate salt, selected from the group consisting of l,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 1,8- diazabicyclo[5.4.0]undec-7-ene (DBU), potassium carbonate (K2CO3), potassium tert-butoxide (KOtBu), and sodium tert-butoxide (NaOtBu), and disodium bisphenol A, wherein the catalyst is present at about 0.01-0.10 equivalents relative to triazine functionality to promote dynamic S\Ar exchange upon heating.

[0076] Item 30. The composition of any preceding Items, wherein repairability is achieved by thermally conditioning the cured article at 90-200 °C for 1-240 minutes in the presence of alcohol, including, PCN polyol prepolymer and a base catalyst, effecting self- healing of microcracks and reduction of residual stress via bond exchange in the cyanurate network.

[0077] Item 31. The composition of any preceding Items, wherein the cured network is chemically degradable at end-of-life by reverse SN Ar depolymerization, comprising contacting the article with a lower alcohol selected from methanol and ethanol in the presence of a base selected from K2CO3, alkali tert-butoxides, and TBD, thereby forming soluble triazine intermediates and alcoholates.

[0078] Item 32. The composition of any preceding Items, wherein ethanol / IGCOs is employed to convert the network to soluble triazine species and alcohol fragments, enabling closed-loop recycling by recovery and reuse of triazine-containing intermediates in the preparation of the prepolymerv

[0079] Item 33. The composition of any preceding Items, wherein recycled triazine intermediates obtained from the degradability process are re-functionalized with mono-ols,Docket No. ROCT.P2007WO / 00651221 diols, or polyols to regenerate the hydroxyl-functional prepolymer for remanufacture of cyanurate-rich articles.

[0080] Item 34. A method of preparing a composition comprising a hyperbranched polycyanurate prepolymer, the method comprising

[0081] (A) reacting a triazine compound having three alkoxy and / or aryloxy leaving groups with an alcohol component comprising one or more of mono-ols, diols, and polyols in a reversible nucleophilic aromatic substitution (S\Ar) to obtain a prepolymer having a hyperbranched architecture.

[0082] Item 35. The method of Item 34, further comprising

[0083] (B) reacting the prepolymer obtained in Item 34 with one or more co-reactants selected from: alcohols, cyanurates, isocyanates, epoxy monomers or prepolymers, and ester- forming reagents comprising diacids, diesters, anhydrides, acid chlorides, and lactones.

[0084] Item 36. The method of any of Items 34-35, wherein the composition is curable to a cyanurate-rich thermoset network, and wherein the prepolymer has low viscosity at high functional-group density suitable for high-solids processing.

[0085] Item 37. A method of using the composition of any of Items 1-33 to make a product suitable for functioning in a certain environment, wherein the certain environment requires low dielectric constant / loss, low moisture uptake, radiation tolerance, and / or cryogenic stability.Examples

[0086] The following examples are provided to illustrate specific embodiments of the current disclosure and to demonstrate the features and advantages of the embodiments but are not intended to limit the scope thereof. Instead, the examples guide one of ordinary skill in the art in understanding and applying the inventive concepts of the disclosure.Synthesis of PCN Prepolymers

[0087] Reagents and Stoichiometry: A triazine electrophile such as 2,4,6-triethoxy- 1,3,5-triazine (TETA) is reacted with an alcohol feed comprising one or more of:

[0088] Diols (e.g., ethylene glycol, 1,4-butanediol, hexanediol, polyether diols, bisphenol- A);

[0089] Mono-ols (e.g., n-butanol, benzyl alcohol) to moderate molecular weight and cap chain ends; and

[0090] Polyols (e.g., glycerol, pripol™, trimethylolpropane, pentaerythritol) to raise branching / functional density.Docket No. ROCT.P2007WO / 00651221Synthesis of hydroxyl-terminated PCN prepolymer

[0091] In exemplary embodiments, 1.5-3 equivalents of total OH per alkoxy / aryoxy triazine are employed to drive formation of oligomers with plural reactive hydroxyl groups (aliphatic or phonolic) and minimal chain entanglement, yielding low solution / melt viscosity at high solids.Reaction Conditions and Volatile Removal

[0092] S\Ar is conducted neat or in an inert solvent (e.g., anisole), typically at 60- 140 °C. A base (e.g., carbonate, alkaline oxide) or nucleophilic catalyst can be used to accelerate exchange. After reaching the targeted substitution, volatile alcohol byproducts (e.g., ethanol from TETA) are removed by vacuum stripping and / or sparging, producing a bubble- free PCN polyol suitable for downstream processing at high solids with smooth flow.

[0093] In representative preparations, 1.0 equivalent of TETA is combined with about 4.0 equivalents of a selected diol and heated at approximately 140 °C under inert atmosphere overnight (e.g., 12-20 h). Catalysis may be effected by either:• a heterogeneous base such as potassium carbonate (K2CO3) at -0.03-0.06 equivalents relative to TETA, which can be mechanically separated (e.g., by centrifugation or filtration) post-reaction; or• a homogeneous organobase such as l,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at ~0.03-0.06 equivalents relative to TETA, enabling a single-pot, homogeneous process.

[0094] The diol component can be selected from ethylene glycol, 1,4-butanediol, 1,6- hexanediol, 1,12-dodecane diol, bisphenol A, and other aliphatic or aromatic diols.Example 1

[0095] A mixture of TETA (1.0 eq), ethylene glycol (4.0 eq), and TBD (0.06 eq) was heated at 140 °C 8-24 h. The product was a low-viscosity liquid, consistent with partial substitution and suppressed network growth under these homogeneous conditions.

[0096] Using 1,4-butanediol (4.0 eq) at 140 °C 8-24 h, both K^CCh-catalyzed and TBD- catalyzed reactions afforded cyanurate -based polyol mixtures exhibiting similar apparent reactivity (viscosity and substitution profiles within expected ranges for partially polymerized materials).Docket No. ROCT.P2007WO / 00651221

[0097] Using 1,6-hexanediol (4.0 eq) at 140 °C 8-24 h, both K^CCh-catalyzed and TBD-catalyzed produced partially polymerized PCN polyols with comparable conversion by spectroscopic analysis.

[0098] The partially polymerized mixtures obtained herein contain PCN oligomers bearing multiple hydroxyl groups in combination with free diol. Such mixtures may be:• used as-is as low-viscosity, PCN-rich polyols in PCN-PU, PCN-EP, or PCN-PE hybrid formulations;• advanced in a subsequent step (e.g., removal of residual diol, controlled chain extension) prior to final cure; and / or formulated as additives / plasticizers to modulate viscosity, residual stress, and toughness• DiokTETA ratio: about 2.5:1 to 6: 1 molar ratio, preferably -4: 1 for partial polymerization.• Catalyst loading: about 0.01-0.10 eq vs TETA; exemplary 0.06 eq for both K2COs and TBD at 140 °C.• Temperature / time: about 120-160 °C for 8-24 h, adjusted to balance substitution rate and avoid gelation where a liquid polyol product is desired.Example 2 Synthesis of cyanurate-capped PCN prepolymer

[0099] In exemplary embodiments, 0.2-0.6 equivalents of total OH per alkoxy / aryoxy triazine functional group are employed to drive formation of oligomers with plural reactive alkoxy / aryoxy triazine groups and minimal chain entanglement, yielding low solution / melt viscosity at high solids.Reaction Conditions and Volatile Removal

[0100] S\Ar is conducted neat or in an inert solvent (e.g., anisole), typically at 60- 140 °C. A base (e.g., carbonate, alkaline oxide) or nucleophilic catalyst can be used to accelerate exchange. After reaching the targeted substitution, volatile alcohol byproducts (e.g., ethanol from TETA) are removed by vacuum stripping and / or sparging, producing a bubble- free PCN prepolymer (Oligo-PCN) suitable for downstream processing at high solids with smooth flow.• DiokTETA ratio: about 0.3:1 to 1:1 (OH equivalents basis), preferably -0.75:1 for partial polymerization.Docket No. ROCT.P2007WO / 00651221• Catalyst loading: about 0.01-0.10 eq vs TETA; exemplary 0.06 eq for both K2COs and TBD at 140 °C.• Temperature / time: about 120-160 °C for 8-24 h, adjusted to balance substitution rate and avoid gelation.

[0101] In representative preparations, 1.0 equivalent of TETA is combined with about 0.75 equivalents of a selected diol and heated at approximately 80-100 °C under inert atmosphere overnight (e.g., 12-20 h). Catalysis may be effected by either:• a heterogeneous base such as potassium carbonate (K2CO3) at -0.03-0.06 equivalents relative to TETA, which can be mechanically separated (e.g., by centrifugation or filtration) post-reaction; or• a homogeneous organobase such as l,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at ~0.03-0.06 equivalents relative to TETA, enabling a single-pot, homogeneous process.

[0102] The partially polymerized mixtures can be used as-is as low-viscosity, oligomeric PCNs, and / or formulated as additives / plasticizers to modulate viscosity, residual stress, and toughness.

[0103] A mixture of TETA (1.0 eq), 1,4 hexane diol (0.75 eq), and TBD (0.06 eq) was heated at 100 °C 18 h. The product was a pale opaque low-viscosity liquid, consistent with partial substitution and suppressed network growth under these homogeneous conditions. The partially polymerized mixtures obtained contain PCN oligomers bearing multiple alkoxy cyanurate groups. Such mixtures may be:• formulated as additives / plasticizers to modulate viscosity, residual stress, and toughness during cyanurate trimerization of aryl cyanate esters, without disrupting• Post-processing: Added more diols (0.75 eq. e.g., 1,6-hexane diol) to the above oligo- PCN prepolymer and the mixture was heated at 100-140 °C for 18 h to develop clear PCN thermoset films.Example 3 Formation of PCN Thermoset Films

[0104] Producing neat polycyanurate (PCN) films free of bubbles can be challenged by the interplay between condensation reaction kinetics and evaporation of the alcohol byproduct (e.g., ethanol) generated during triazine S\Ar exchange. When the rate of network formation outpaces the rate of volatile egress, the rapidly increasing viscosity traps volatiles and yields foam- like defects.Docket No. ROCT.P2007WO / 00651221

[0105] To address volatile entrapment, the invention provides process controls that decouple cure kinetics from volatilization, including: (i) temperature programming (lower or staged cure), (ii) catalyst loading reduction, and (iii) optional transient plasticization (e.g., with anisole) to lower viscosity and enhance volatile transport. These controls can be used independently or in combination and are compatible with PCN prepolymer routes and direct film casting on inert or release-treated substrates. PCN final formulations contained TETA and 1.5 equiv of a diol (1:1 stoichiometry reactive polymerizable groups), with TBD as S\Ar base catalyst. Films were cast and cured isothermally at 120 °C:• Scheme 1 (0.06 equiv TBD vs TETA): Full cure achieved within <18 h, but visible bubbling and voids were observed due to excessive cure rate relative to ethanol evaporation.• Scheme 2 (0.03 equiv TBD): Full cure within <18 h with a pristine, bubble-free film. This loading balanced cure and volatilization rates, permitting ethanol egress prior to vitrification.• Scheme 3 (0.01 equiv TBD): The film remained a viscous, partially cured gel after the same time, indicating under-catalysis and insufficient network formation at 120 °C.

[0106] The optimized 0.03 equiv TBD condition was further applied to 1,4-butanediol and 1,12-dodecanediol systems, yielding defect- free films under otherwise identical conditions. For 1,4-butanediol, adhesion to the substrate was comparatively strong.

[0107] In certain prior workflows, anisole or analogous high-boiling diluents may be introduced to temporarily plasticize the growing network, lowering viscosity and improving volatile transport during cure at 120-140 °C.

[0108] Non-limiting base candidates include l,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), potassium carbonate (K2CO3), potassium tert-butoxide (KOtBu), and sodium tert-butoxide (NaOtBu), disodium bisphenol A. In embodiments, base loading is about 0.01-0.10 equivalents relative to the triazine (e.g., TETA), preferably 0.02-0.06 equivalents. Temperature can be controlled within 100-140 °C, staged holds (e.g., 100-110 °C devolatilization 120-130 °C advancement) under dry N2; limit oxygen exposure to reduce color development with organic superbases. To control the development yellow color, employ shorter high-T dwells, antioxidants, and lower base loadings; for optical- sensitive dielectric films, K2CO3 or dual-base strategies (brief KOtBu / TBD initiation then K2CO3 finish) can be used.Docket No. ROCT.P2007WO / 00651221

[0109] All bases showed some solubility in TETA; K2CO3 was only partially soluble at the tested loading. Addition of KOtBu or NaOtBu produced a color shift in TETA (clear — slightly yellow / amber), while TBD and DBU yielded homogeneous solutions but may contribute to color development at elevated temperature. Partial solubility can be advantageous when heterogeneous removal (e.g., filtration / centrifugation) is desired; complete solubility favors single-pot processing. Upon heating, most bases promoted progression toward substitution; however, DBU and K2CO3 displayed slower rates and plateaued before full conversion under the test conditions. TBD and KOtBu exhibited the fastest apparent rates; NaOtBu performed similarly to KOtBu.

[0110] TBD offers high reactivity and homogeneous, single-pot processing, making it a preferred catalyst for efficient S\Ar and low-viscosity prepolymer formation, particularly where throughput is prioritized. To mitigate yellowing at elevated temperature, embodiments use lower loadings (e.g., -0.02-0.04 eq), inert atmospheres, antioxidants, and / or staged cures (initial lower-temperature hold to vent volatiles, followed by higher-temperature advancement).

[0111] K2CO3 provides excellent color stability and low discoloration, with the benefit of heterogeneous removal; however, partial solubility and slower kinetics may require higher temperature, longer dwell, or increased loading to reach target conversion.

[0112] KOtBu and NaOtBu deliver fast kinetics comparable to TBD, but can induce a color shift in TETA upon mixing; these bases are advantageous when rapid substitution is required and optical / yellowing constraints are secondary or can be addressed by process controls (e.g., reduced residence time at peak temperature). Fig. 4 shows the kinetic profiles of the S\Ar reaction using different base catalysts.

[0113] DBU is generally slower and more color-prone under the test conditions and may be reserved for systems requiring milder basicity or specific compatibilities.

[0114] Reducing base catalyst from 0.06 eq to 0.03 eq to TETA produced films with increased tensile modulus and tensile strength without sacrificing elongation at break. It is believed that slower cure kinetics at 0.03 eq synchronize network growth with byproduct (ethanol) removal, minimizing early vitrification and bubble entrapment and thus enabling higher conversion and improved properties.

[0115] Thermal post-curing further increased modulus and strength, indicating that the initial cure was incomplete under the as-cast schedule. Accordingly, the disclosure contemplates staged thermal profiles (e.g., devolatilization hold below vitrification temperature followed by higher-temperature advancement) and extended post-cures to reach full conversion and optimize properties.DocketNo. ROCT.P2007WO / 00651221

[0116] To verify conversion, Fourier-transform infrared spectroscopy (FTIR) was employed to monitor polymerization. In embodiments, FTIR data were used to determine minimum post-cure time / temperature needed for complete reaction for a given thickness and catalyst loading. Elevated post-cure temperatures and / or longer dwell times are contemplated for bulk films relative to thin coatings.Generalized Process Window to form bubble-free films• Catalyst (base) loading: about 0.015-0.06 equiv vs TETA, preferably -0.02-0.04 equiv; optimized herein at -0.03 equiv for 120 °C cures.• Temperature: 90-140 °C; in embodiments, 120 °C affords a practical balance of cure rate and volatile removal; staged profiles (e.g., 100 °C hold for ethanol egress — 120- 130 °C to drive conversion) are contemplated.• Thickness: thinner wet films (<50-75 pm) facilitate volatile escape; thicker sections may use step-coating with intermediate devolatilization holds.

[0117] By tuning catalyst loading and cure temperature, the process prevents bubble entrapment without resorting to high-pressure reactors. The resulting neat PCN films exhibit uniform morphology, low dielectric loss, and surface integrity suitable for advanced coatings, laminates, and electronic insulation. The same control strategy is applicable to variant diols (aliphatic, cycloaliphatic, aromatic, polyether) and to hybrid PCN systems (e.g., PCN-PU, PCN-EP, PCN-polyester), maintaining industrially compatible cure schedules.Example 4 Formation of Hybrid NetworksExample 4a Preparation of alkyl and aryl PCN hybrid

[0118] Route A — In-situ SNAr with mixed diols (baseline).Alkyl-aryl PCN hybrids are synthesized by SN Ar between a triazine electrophile and a mixture of alkyl diols and aromatic diols to enhance toughness relative to neat aryl PCNs. A representative process employs TETA and a multi-ol feed at ~1:1 functional-equivalent stoichiometry, forming a crosslinked network with ethanol as byproduct. Volatile ethanol is removed under vacuum (optionally with inert sweep and staged temperature holds), consistent with condensation polymer practice (polyesters, polyamides, phenolics), thereby limiting voids, defects, and outgassing.

[0119] Mechanical properties are tuned by the alkyl: aromatic diol ratio: more alkyl diol lowers modulus and increases compliance; more aromatic diol increases rigidity and heat resistance. Feed strategy reflects nucleophile reactivity: alkyl alcohols are more nucleophilic than phenols and thus react faster with TETA.

[0120] Polymerization kinetics are modulated by the triazine leaving group. Aromatic diols exchange more readily with aryloxy triazines than with alkoxy triazines; therefore, 2,4,6-Docket No. ROCT.P2007WO / 00651221 triphenoxy- 1, 3, 5-triazine can be used to adjust rate and sequence of incorporation. Phenol byproduct formed in this case is removed by the same vacuum / volatilization methods.

[0121] Combining (i) controlled alkyl / aromatic diol ratios with (ii) leaving-group engineering yields high-performance alkyl / aryl PCN hybrids with tailored mechanics and robust processability.Route B — PCN-polyol-enabled formation of alkyl / aryl PCN hybrids (prepolymer route).

[0122] To mitigate byproducts during network formation and improve defect control, an alternative PCN-polyol route is employed:1. Synthesis of PCN polyol (hydroxyl-functional PCN prepolymer).Prepare a hydroxyl-functional, hyperbranched PCN polyol by SN Ar between a trialkoxy and / or triaryloxy triazine (e.g., TETA or triphenoxy triazine) and one or more alcohol components (mono-ols / diols / polyols), chosen to embed alkyl segments, aromatic segments, or both into the prepolymer backbone. Conduct the reaction under conditions that allow complete removal of low-boiling byproducts (e.g., ethanol and, where applicable, phenol), yielding a PCN polyol with controlled OH functionality and low viscosity.2. Network formation using PCN polyol.Form the alkyl / aryl PCN hybrid network by reacting the PCN polyol with complementary triazine electrophiles (alkoxy and / or aryloxy triazines) and / or with other cyanate-forming monomers, using a staged thermal schedule that maintains byproduct removal below vitrification. The alkyl vs. aromatic content of the final network is governed by the PCN polyol composition (alkyl-rich, aromatic-rich, or mixed) and the electrophile set used in the network-building step.3. Optional capped oligomeric plasticizer.A portion of the PCN polyol may be end-capped (e.g., etherified / esterified) to render it substantially nonreactive under cure conditions, producing a PCN-compatible oligomeric plasticizer. This capped prepolymer can be blended into aryl cyanate trimerization or SNAr-based PCN matrices to increase toughness and reduce residual stress while avoiding in-situ volatile evolution during final cure.

[0123] Relocating volatile removal to the prepolymer stage helps prevent bubble formation, reduce outgassing, and simplify defect control in thick sections or films.Docket No. ROCT.P2007WO / 00651221Additionally, the PCN polyol route minimizes formation of problematic side species (e.g., isocyanate-ester-type impurities) that have hindered some alkyl-PCN formulations, thereby improving formulation robustness.Example 4b PCN-Poly urethane (PCN-PU)

[0124] PCN polyols were reacted with di- / polyisocyanates (e.g., MDI, IPDI, HDI, H12MDI) with or without using catalysts. Urethane formation may proceed at ambient-120 °C. The resulting hybrids combine urethane segments with cyanurate domains.Example 4c PCN-Epoxy (PCN-EP)

[0125] Route A — Direct reaction of PCN polyol with epoxy resins (ring-opening cure) In one embodiment, a hydroxyl-functional PCN prepolymer (“PCN polyol”) was directly reacted with an epoxy resin to form a PCN-epoxy (PCN-EP) hybrid without prior epoxidation of the PCN polyol. Fig. 6 illustrates the ring-opening reaction of a 1,4-butanediol-containing PCN polyol with bisphenol-A diglycidyl ether (BADGE) to yield a PCN-epoxy thermoset.

[0126] Processing window. Conducted an epoxy advance at -100-170 °C (monitor epoxide equivalent weight or residual epoxide), followed by an optional post-cure at -180- 210 °C to complete network development.

[0127] Stoichiometry. Set the Epoxy: OH equivalent ratio (epoxide equivalents : hydroxyl equivalents of PCN polyol) to -0.6-1.5 : 1, adjusted to achieve the desired crosslink density and toughness.Route B — Pre-epoxidized PCN polyol (PCN-EP prepolymer) then cure / co-cure

[0128] In another embodiment, PCN polyols are converted to polyepoxide prepolymers by etherification with epichlorohydrin under basic conditions, yielding a PCN-EP prepolymer. Target epoxide equivalent weight (EEW) by controlling conversion and residual OH.

[0129] Cure modes, (i) Self-cure: PCN-EP cured alone using amine, anhydride, or cationic / onium systems; staged 120-170 °C advance — 180-210 °C post-cure.

[0130] (ii) Co-cure with additional epoxy monomers: Blend PCN-EP with diglycidyl / difunctional and / or multifunctional epoxies; cure as above.

[0131] Process sequencing. A representative schedule is 120-150 °C (epoxy advance; devolatilization) — 170-190 °C (network development) — 190-210 °C (final conversion of residual epoxy / cyanurate formation).Docket No. ROCT.P2007WO / 00651221

[0132] Route A enables direct grafting of epoxy onto the PCN framework; Route B allows precise epoxide functionality and broad co-curing latitude with standard epoxy toolkits.

[0133] Additives: flow aids, adhesion promoters, antioxidants / UV stabilizers may be included at <2 wt% total to preserve dielectric performance.Example 4d. PCN-Polyester (PCN-PE)

[0134] In another embodiment, a PCN polyol is polymerized through esterification with ester- forming derivatives to yield a PCN-grafted polyesters:

[0135] Ester-forming derivatives: diacids (adipic, sebacic, azelaic, terephthalic, isophthalic), diesters / di-methyl esters, anhydrides (phthalic, maleic), acid chlorides, and lactones (s-caprolactone).

[0136] Catalysts / conditions: titanium alkoxides, tin(II) carboxylates, zinc / zirconium salts; melt or solution polycondensation or ring-opening polymerization at 80-180 °C, optionally with azeotropic or vacuum water / alcohol removal.

[0137] Polyester segments impart toughness and bend compliance, while the PCN phase maintains low dielectric constant / loss, low moisture uptake, radiation resistance, and thermal-cycling durability.Example 4e. Capping to Form Non-Reactive Plasticizers

[0138] In another embodiment, the hydroxyl groups of the hydroxyl-functional PCN polyol are deactivated (“capped”) by reaction with monofunctional reagents, thereby rendering the prepolymer substantially non-reactive under typical cure conditions and suitable as a PCN- compatible oligomeric plasticizer to improve toughness and processing of cyanurate matrices.

[0139] Suitable capping chemistries include, without limitation:

[0140] (i) Ether formation via alkyl halides (e.g., haloalkanes) to give alkyl-ether end groups;

[0141] (ii) Carbamate (urethane) formation via alkyl isocyanates (e.g., hexyl isocyanate) to give urethane-capped termini;

[0142] (iii) Ester formation via acid chlorides or anhydrides;

[0143] (iv) Carbonate or silyl-ether capping for tailored stability; and

[0144] (v) Hydrophilicity / flexibility modification by installing poly(ethylene glycol) (PEG) or other mono-functional chains.

[0145] The degree of capping can be adjusted (e.g., 50-100 mol % of available -OH) to balance compatibility, plasticization efficiency, and storage stability. Because the prepolymer possesses a hyperbranched, dendrimer-like architecture with minimal chainDocket No. ROCT.P2007WO / 00651221 entanglement, the capped product maintains low viscosity at high solids, enabling solvent-free blending and void-free processing. When incorporated at, for example, -1-15 wt % into cyanurate-forming formulations (including aryl-PCN varnishes produced by trimerization or SNAr-based PCN systems), the capped prepolymer reduces modulus and residual stress, increases fracture toughness and bend compliance, and preserves low dielectric loss and low moisture uptake due to its PCN-compatible backbone. In certain embodiments, the capping groups are substantially non-exchangeable under the selected cure profile (e.g., <230 °C, neutral to mildly basic conditions), thereby preventing unwanted side-reactions while delivering durable toughening and process-wide compatibility.Example 5 Dynamic Covalent Behavior: Self-Healing and Recycling

[0146] The S\Ar exchange on triazines can be rendered dynamic in the presence of bases such as TBD, alkaline alkoxide, or carbonate, providing reversible covalent bonds within the PCN architecture. Under appropriate triggers (e.g., heat, base, solvent), bonds break and reform, enabling:

[0147] Self-healing: stress relaxation and closure of microcracks via bond reshuffling within the network;

[0148] Reworkability / repairability: partial network flow and re-bonding under controlled stimuli; and

[0149] Closed-loop recycling: end-of-life depolymerization of PCNs via reverse S\Ar, converting the network into soluble triazine intermediates and alcohol fragments (e.g., using ethanol / IGCOs), followed by re-monomerization / reuse.

[0150] Fig. 11 shows exemplary lamination (“welding”) using dynamic S\Ar. TWO 1,6- hexanediol-based PCN films were stacked with an interlayer solution comprising a 1,6- hexanediol and TBD (10 mol% relative to total -OH) and heat-pressed at -120 °C under minimal pressure. The basic interlayer activates interfacial S\Ar exchange, producing covalent bonding across the interface. After a brief dwell, the laminate exhibited a continuous, void-free bondline with no visible interface, evidencing chemical lamination enabled by reversible S\ Ar exchange. This process serves as a practical demonstration of rep airability / re workability for PCN articles without introducing foreign adhesives or compromising dielectric and environmental performance.Example 6 Performance and Suitability

[0151] The PCN network materials produced by the foregoing embodiments are engineered for high-performance environments, including space hardware, fusion-magnetDocket No. ROCT.P2007WO / 00651221 insulation, and aerospace electronics, where radiation resistance, low outgassing, low water uptake, low dielectric constant / loss, cryogenic strength retention, and thermal-shock durability are critical. The prepolymer strategy provides industrial compatibility (varnish processing, high solids, smooth flow) while the dynamic S\Ar capability offers self-healing, reworkability, and closed- loop recycling pathways.

[0152] As depicted in Fig. 8, PCN films produced from TETA and 1,6-hexanediol were evaluated for electromagnetic interference (EMI) transmission over 30 kHz to 26.5 GHz. The 1,6-hexanediol-based PCN films were substantially transparent across the measured frequency range. When normalized for thickness, the PCN films showed lower measured intensity across the band compared with common plastics (e.g., PET, PTFE, LDPE) used as references. Without limiting the invention, the data indicate low dielectric loss and minimal conductive attenuation typical of non-filled, low-loss thermosets, supporting use in RF-transparent radomes, conformal coatings, and EMI-benign encapsulants.

[0153] Exposure of as-cured PCN films to 385 nm high-intensity UV under the stated conditions produced no statistically significant change in modulus, tensile strength, or elongation relative to non-exposed controls.Cryogenic Cycling Protocol and Results (Fig. 9&10)

[0154] As depicted in FIG. 9, films were bent at room temperature (RT), then immersed in liquid nitrogen (77 K) for about 8 hours, removed and allowed to warm to RT, and subsequently tested in tension. This cycle was repeated twice for mechanical comparison, and in additional trials five consecutive cycles are conducted in which the last three cycles use 10- minute immersions at 77 K.

[0155] 1,6-hexanediol-based and 1,12-dodecanediol-based PCN films showed:• Full resistance to permanent deformation: bent specimens returned to a flat, original geometry upon warming to RT;• Negligible change in tensile properties after two full thermal cycles;• No visible warpage or set even after five consecutive cycles, including short-duration cryogenic soaks.

[0156] These observations demonstrate that the disclosed PCN films recover fully from extreme thermal excursion without plastic set or microcrack- induced distortion under the tested conditions.

[0157] Under the same thermal-cycling protocol, PTFE films exhibited irreversible deformation after a single cycle (bent geometry not restored upon warming). The contrastDocket No. ROCT.P2007WO / 00651221 indicates that the disclosed PCN materials provide superior resistance to cryogenic cycling- induced shape change relative to PTFE of comparable thickness.

[0158] The combination of cryogenic shape recovery, mechanical property retention, and chemical / thermal robustness renders the disclosed PCN films well-suited for applications requiring repeated cycling between RT and cryogenic temperatures, including fusion-magnet insulation, space hard and soft dust repellent coatings, cryogenic electronics encapsulation, radome / conformal coatings, and vacuum-compatible insulating layers.

Claims

Docket No. ROCT.P2007WO / 00651221Claims1. A polycyanurate prepolymer, comprising a plurality of 1,3,5-triazine (“cyanurate”) nodes covalently linked through — O — R — O — linkage, the polycyanurate prepolymer having a plurality of terminal groups, wherein the terminal group is (a) hydroxyl groups (hydroxyl-terminated polycyanurate prepolymer, “PCN polyol”), or (b) alkoxy and / or aryloxy triazine groups (triazine-terminated polycyanurate prepolymer), wherein R is(i) C1-C30 alkylene, C3-C20 cycloalkylene, C6-C20 arylene, or C7-C20 aralkylene, each optionally substituted with Ci-Ce alkyl, halo, cyano, or Ci-Ce alkoxy;(ii) heteroatom-interrupted groups in which the alkylene or aralkylene backbone is optionally interrupted by — O — , — S — , — NR' — , — CO — , — COO — , — OCO — , — SO2 — , carbonate, or urethane (carbamate) linkages;(iii) poly(alkylene oxide) segments of the formula — (CH2CHR'0)n— where R' = H or C1-C4 alkyl and n = 2-500 (including PEG, PPG, PTMEG);(iv) aromatic diol residues including phenylene-, biphenyl-, or bisphenol-type residues (e.g., resorcinol, hydroquinone, bisphenol structures) optionally bearing alkyl, halo, alkoxy, or perfluoroalkyl substituents;(v) siloxane-containing segments of the formula — [Si(R")2 — O]m— where R" is Ci-Ce alkyl or phenyl and m = 2-500; or(vi) combinations and copolymeric sequences of any of (i)-(v);2. The polycyanurate prepolymer of claim 1, wherein the terminal groups are the same within same prepolymer.

3. The polycyanurate prepolymer of claim 1, obtained by reversible nucleophilic aromatic substitution (SNAT) between a triazine compound having three alkoxy and / or aryloxy leaving groups and an alcohol component comprising one or more of mono-ols, diols, and polyols, the prepolymer having a hyperbranched architecture.

4. A composition comprising the polycyanurate prepolymer of claim 1, wherein said composition is curable.Docket No. ROCT.P2007WO / 006512215. The composition of claim 4, obtained by reacting the prepolymer obtained in claim 3 with one or more co-reactants selected from: alcohols, cyanurates, isocyanates, epoxy monomers or prepolymers, and ester-forming reagents comprising diacids, diesters, anhydrides, acid chlorides, and lactones; wherein the composition is curable to a cyanurate- rich thermoset network, and wherein the prepolymer provides low viscosity at high functional-group density suitable for high-solids processing.

6. The polycyanurate prepolymer of claim 1, wherein the 1,3,5-triazine node comprises 2,4,6-alkoxy-l,3,5-triazine or 2, 4, 6-tri(aryloxy)- 1,3,5-triazine.

7. The polycyanurate prepolymer of claim 3, wherein the alcohol component comprises at least one multivalent alcohol selected from aliphatic and / or aromatic (phenolic) diols and polyols to introduce branching.

8. The polycyanurate prepolymer of claim 3, wherein the prepolymer has an OH value of about 50-600 mg KOH / g and a solution viscosity at 60-80 wt% solids of about 100-2,000 cP at 25 °C.

9. The polycyanurate prepolymer of claim 3, wherein the S\Ar stoichiometry and sequence are selected to provide hydroxyl-terminated prepolymer end groups.

10. The polycyanurate prepolymer of claim 8, further comprising alkoxy and / or aryloxy triazines as co-reactants such that hydroxyl-terminated oligomers are polymerized therewith to yield a polycyanurate thermoset.

11. The polycyanurate prepolymer of claim 3, wherein the S\Ar stoichiometry and sequence are selected to provide alkoxy- or aryloxy -triazine terminated oligomers.

12. The polycyanurate prepolymer of claim 11, further comprising polyols or other multifunctional nucleophiles as co-reactants, wherein alkoxy- / aryloxy-terminated oligomers are polymerized therewith to yield a cyanurate-rich network.

13. The composition of claim 5, wherein the co-reactant set comprises an isocyanate, and curing yields a PCN-polyurethane (PCN-PU) hybrid having urethane soft segments integrated with cyanurate domains.Docket No. ROCT.P2007WO / 0065122114. The polycyanurate prepolymer of claim 3, wherein the prepolymer is etherified with epichlorohydrin to form a poly epoxide.

15. The composition of claim 5, wherein the one or more co-reactants comprise an epoxy curing agent and optionally additional epoxy monomers, thereby yielding a PCN- epoxy (PCN-EP) hybrid on cure.

16. The composition of claim 5, wherein the one or more co-reactants comprise one or more ester-forming reagents selected from diacids, diesters, anhydrides, acid chlorides, and lactones, thereby yielding a PCN-polyester (PCN-PE) hybrid on cure.

17. The polycyanurate prepolymer of claim 3, wherein at least a portion of the terminal hydroxyl groups of the prepolymer are capped by ether, ester, or carbamate (urethane) formation to provide a substantially non-reactive, PCN-compatible plasticizer.

18. The polycyanurate prepolymer of claim 17, wherein the capped prepolymer is present at about 0.5-15 wt% of the total composition and is blended with aryl cyanate esters to reduce modulus and residual stress and increase toughness during trimerization.

19. The composition claim 5, wherein the composition further comprises a cyanurate- formation catalyst selected from the group consisting of l,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), potassium carbonate (K2CO3), potassium tert-butoxide (KOtBu), and sodium tert-butoxide (NaOtBu), disodium bisphenol A, and combination thereof, and wherein the composition is curable under a staged thermal profile comprising holds between about 100-230 °C, or between about 100 -140 °C.

20. The composition of claim 5, wherein volatile byproducts generated during prepolymer preparation are removed prior to use of the composition, thereby enabling bubble- free films at >60 wt% solids.

21. The composition of claim 5, wherein the cured thermoset network exhibits at least one of the following properties: dielectric constant <3.2 (1 MHz- 10 GHz), moisture uptake <1.5 wt%, low outgassing compatible with vacuum applications, or improved tensile toughness relative to neat aryl polycyanurates.Docket No. ROCT.P2007WO / 0065122122. The polycyanurate prepolymer of claim 3, wherein the prepolymer exhibits a hyperbranched topology that minimizes chain entanglement relative to linear polymers at comparable functionality.

23. The composition of claim 4, wherein the composition is curable to provide coatings, encapsulants, laminates, adhesive films, or insulation.

24. The composition of claim 5, wherein the cyanurate-rich fraction constitutes 30-70 mol% or 70-95 mol% of total curable functionality in the cured network.

25. The polycyanurate prepolymer of claim 3, wherein the alcohol component comprises a mixture of aliphatic and aromatic alcohols to tune modulus and toughness, and the triazine leaving group set (alkoxy vs. aryloxy) is selected to control S\Ar kinetics.

26. The composition of claim 5, wherein the composition excludes added solvents during final cure and achieves uniform, defect-free films by virtue of the low viscosity of the prepolymer.

27. The composition of claim 5, wherein the cured network is configured for aerospace, electronics, RF / antenna covers, protective coatings, or advanced insulation applications requiring thermal stability, dielectric performance, low moisture uptake, cryogenic cycling, and toughness.

28. The composition of claim 5, wherein the cured network comprises reversibly exchangeable triazine-alkoxy and / or triazine-aryloxy linkages configured to undergo basecatalyzed exchange, thereby providing repairability including stress relaxation, crack healing, and reshaping without loss of cyanurate content.

29. The composition of claim 27, wherein the composition further comprises a latent or active base catalyst selected from a carbonate salt, selected from the group consisting of l,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), l,8-diazabicyclo[5.4.0]undec-7-ene (DBU), potassium carbonate (K2CO3), potassium tert-butoxide (KOtBu), and sodium tert-butoxide (NaOtBu), and disodium bisphenol A, wherein the catalyst is present at about 0.01-0.10 equivalents relative to triazine functionality to promote dynamic SN Ar exchange upon heating.Docket No. ROCT.P2007WO / 0065122130. The composition of claim 28, wherein repairability is achieved by thermally conditioning the cured article at 90-200 °C for 1-240 minutes in the presence of alcohol, including, PCN polyol prepolymer and a base catalyst, effecting self-healing of microcracks and reduction of residual stress via bond exchange in the cyanurate network.

31. The composition of claim 28, wherein the cured network is chemically degradable at end-of-life by reverse SN Ar depolymerization, comprising contacting the article with a lower alcohol selected from methanol and ethanol in the presence of a base selected from K2CO3, alkali tert-butoxides, and TBD, thereby forming soluble triazine intermediates and alcoholates.

32. The composition of claim 30, wherein ethanol / K^COs is employed to convert the network to soluble triazine species and alcohol fragments, enabling closed-loop recycling by recovery and reuse of triazine-containing intermediates in the preparation of the prepoly merv33. The composition of claim 32, wherein recycled triazine intermediates obtained from the degradability process are re-functionalized with mono-ols, diols, or polyols to regenerate the hydroxyl-functional prepolymer for remanufacture of cyanurate-rich articles.

34. A method of preparing a composition comprising a hyperbranched polycyanurate prepolymer, the method comprising(A) reacting a triazine compound having three alkoxy and / or aryloxy leaving groups with an alcohol component comprising one or more of mono-ols, diols, and polyols in a reversible nucleophilic aromatic substitution (S\Ar) to obtain a prepolymer having a hyperbranched architecture.

35. The method of claim 34, further comprising(B) reacting the prepolymer obtained in claim 34 with one or more co-reactants selected from: alcohols, cyanurates, isocyanates, epoxy monomers or prepolymers, and ester-forming reagents comprising diacids, diesters, anhydrides, acid chlorides, and lactones.

36. The method of claim 35, wherein the composition is curable to a cyanurate-rich thermoset network, and wherein the prepolymer has low viscosity at high functional-group density suitable for high-solids processing.Docket No. ROCT.P2007WO / 0065122137. A method of using the composition of claim 4 to make a product suitable for functioning in a certain environment, wherein the certain environment requires low dielectric constant / loss, low moisture uptake, radiation tolerance, and / or cryogenic stability.

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