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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Designing Recyclable Biomass-Based Polyesters (Final Technical Report)

This project successfully demonstrated the production of sustainable polyesters from biomass-derived monomers, offering properties on par with or superior to fossil-based plastics such as LLDPE and PBAT. Using renewable chemical platforms like furfural and HMF, we synthesized over eight novel monomers and nearly 100 aliphatic-aromatic polyesters. Among these, PPeAT and PDDF emerged as highly promising candidates for flexible packaging applications, exhibiting excellent mechanical performance, tunable thermal properties, and enhanced barrier characteristics. Key advances included the development of ring-opening polymerization strategies using cyclic monomer intermediates to produce high molecular weight materials with excellent control. The resulting polymers achieved biobased content of at least 44 wt.%. We also implemented chemical recycling via catalytic methanolysis, recovering over 90% of monomers from PPeAT at semi-pilot scale. This supports a circular economy approach by enabling material reuse without performance loss. Techno-economic and life cycle assessments confirmed that these polyesters can reduce greenhouse gas emissions by up to 50% compared to petroleum-derived alternatives. Favorable mechanical properties may further reduce material demand, and cost competitiveness was demonstrated under specific market conditions. Feedstock cost and environmental footprint were identified as primary levers for future optimization. In summary, the project met or closely approached all technical targets, including biodegradability, strength, and processing compatibility. While minor issues such as color and melting point variation remain, the results strongly support continued development and scale-up of these sustainable materials.

09 BIOMASS FUELS↗
DOE OSTI2025

Tuning Copolymer Microstructure Using Ring-Opening Cross-Metathesis Polymerization

The capability of ring-opening cross-metathesis (RO/CM) polymerization to produce alternating copolymers was studied. By treating commercial polybutadiene (PB) with bulky oxanorbornene monomers and Ru-based olefin metathesis catalysts, alternating copolymers were produced under mild conditions with high sequence fidelities. Here, we found that alternating copolymers could be produced starting from a variety of butadiene sources including PB, cyclooctadiene (COD), or t,t,t-1,5,9-cyclododecatriene (CDT), highlighting for the first time the kinetic pathway independence of this process. Kinetic copolymerization analysis of an oxanorbonene monomer with CDT revealed that much higher monomer conversions were obtained compared with the analogous homopolymerizations and showed evidence of alternating monomer incorporation. Copolymerization of these monomers also enabled good control when targeting different molecular weights. Copolymer thermal analysis revealed a strong correlation between thermal behavior and alternating sequence fidelity, providing a second lever beyond composition to tune thermal behavior. These data demonstrate that a broad variety of polymer microstructures can be accessed via RO/CM polymerization and highlight the potential of CDT in alternating copolymer synthesis.

Foster, Jeffrey C. [Oak Ridge National Laboratory ↗
DOE OSTI2026

Effects of a Small Fraction of Norbornene Comonomers on the Frontal Ring Opening Metathesis Polymerization of Dicyclopentadiene and Dihydrofuran

Frontal ring-opening metathesis polymerization (FROMP) is an energy-efficient process for the construction of high performance polydicyclopentadiene (pDCPD) thermosets. A small fraction of norbornene (NBE) comonomer is often added to DCPD to liquify the resin, but their effects on the resin chemistry and frontal curing characteristics are not quantitatively understood, especially for recently developed deconstructable DCPD resins containing cleavable comonomers. 2,3-Dihydrofuran (DHF) is a commercially available, effective cleavable comonomer for ROMP of norbornenes, and it has been recently demonstrated to enable full deconstruction of pDCPD thermosets at 5% loading. Herein, we investigated deconstructable DCPD resins containing 5% of different (oxa)NBE derivatives and 5% DHF. We report the effects of such a small fraction of (oxa)NBE comonomers on the resin pot life (room temperature resin reactivity), front curing characteristics, degree of cure, crosslinking density, comonomer distribution, and deconstruction kinetics of the resulting pDCPD thermosets. These effects can be correlated to the metathesis reactivity of these comonomers. As a result, this study provides quantitative understanding that will guide the future development of new deconstructable FROMP resins with desired construction and deconstruction characteristics.

Luo, Xuyi [Stanford University, CA (United States)↗
DOE OSTI2025

Videos of Chemically Activated Frontal Polymerization of Thermosets

Video recordings of the frontal ring-opening metathesis polymerization (FROMP) of thermoset polymer specimens in 10mm glass test tubes were collected in order to measure the front speed resulting from varied front initiation methods. Maximum front temperature was also measured. Polymerization resins comprised of dicyclopentadiene (DCPD) with 5 wt% 5-ethylidene-2-norbornene (ENB) added, grubbs’ second generation catalyst, and tributyl phosphite (TBP) inhibitor (8000:1:1 monomer:initiator:inhibitor ratio). Polymerization fronts were triggered using concentrated solutions of grubbs’ third generation catalyst in various solvents.

Cramblitt, Anna C.↗
DOE OSTI2025

Polymer Size–Catalytic Activity Relationships in Solution by Fluorescence Correlation Spectroscopy

Measuring the catalytic activity of specific sizes of polymers with active catalysts in solution is typically challenging, due to limited instrument detection sensitivity and/or dynamic range. Here, a fluorescence correlation spectroscopy (FCS) method is developed to determine the catalytic activity of living polymers of a specific apparent size in solution. Deviation from a single-component FCS data fitting, as assessed by χ2, is also introduced and developed as a “speciation index”—a method to evaluate and track changes in the relative amount of distinct polymer sizes with reaction progress. These methods are enabled by incorporating a selectively reactive fluorescent monomer into growing polydicyclopentadiene or polynorbornene during ring-opening metathesis polymerization (ROMP). Compared to polynorbornene, data showed that catalysts in aggregates of polyDCPD retained higher activity for longer—outcomes not directly inferable from simple diffusional-access predictions. Here, the ability to assign catalytic activity to polymers of specific sizes, and then to determine how this activity evolves with reaction progress, support long-term goals in the development and measurement of nano-objects that possess size-dependent catalytic activity.

Active catalyst↗
DOE OSTI2025

Real-time process monitoring and automated control for direct ink write 3D printing of frontally polymerizing thermosets

Additive manufacturing (AM) enables the fabrication of complex geometries, yet its application to thermosets remains limited by post-processing requirements. Frontal ring-opening metathesis polymerization (FROMP) offers a promising alternative, enabling energy-efficient, in situ curing of freestanding thermoset structures. This study presents a real-time process monitoring and automated control system for direct ink writing (DIW) of FROMP thermosets. By integrating thermochromic leuco dyes and computer vision, we enable real-time polymerization front tracking, allowing autonomous printing parameter adjustments for consistent geometries across resin formulations. The system’s accuracy was validated against manual tracking, demonstrating precise front velocity detection. Its adaptability was confirmed by printing freestanding mechanical springs with different resins, achieving consistent geometries and mechanical properties despite front velocity variations. These findings highlight the potential of automated DIW control for scalable, repeatable, and material-agnostic 3D printing of thermosets.

Mejia, Edgar Brian [Sandia National Laboratories (↗
DOE OSTI2025

Polyhalohydrins: Investigating Vicinal Functionalities by Ring-Opening of Epoxides on Polyolefins

Halohydrins are functional groups that are underexplored in polymer science. This study synthesized and examined structure–property relationships of halohydrin-functionalized polymers derived from polycyclooctene (PCOE), which was obtained via ring-opening metathesis polymerization (ROMP). The polyhalohydrins, including polychlorohydrin, polybromohydrin, and polyiodohydrin, were produced through a two-step process involving epoxidation of PCOE followed by epoxide ring-opening using hydrochloric, hydrobromic, or hydroiodic acid. These stereoirregular and regioirregular polymers are amorphous as measured by differential scanning calorimetry and X-ray scattering. Lap joint shear testing revealed an enhanced adhesive performance in polychlorohydrin and polybromohydrin, with the former demonstrating nearly three times the ultimate shear stress compared to a model polyethylene, hydrogenated PCOE. Additionally, contact angle measurements and surface free energy analysis showed an increase in hydrophilicity and polarity from iodine- to bromine- to chlorine-functionalized polyhalohydrins, aligning with trends in adhesion strength. Furthermore, these results underscore the potential of halohydrin functionalization as a versatile approach for tuning surface properties, offering new opportunities for polymer-to-polymer transformations.

Functional groups↗
DOE OSTI2025

Equilibrium-gated pattern formation: How molecular dissociation thermodynamics drive emergent behavior in dissipative polymeric systems

Emergent patterns in biological systems arise through dissipative processes that balance reaction and transport phenomena, producing highly functional properties from self-regulating mechanisms. Synthetic fabrication, by contrast, often relies on user-controlled, multistep methods that lack the self-organizing capabilities of natural systems. Inspired by nature, we sought chemical systems that integrate strongly coupled reaction and transport phenomena, identifying frontal ring-opening metathesis polymerization (FROMP) as a method capable of creating diverse forms and functions through reactive processing. By employing discrete molecular initiators, FROMP allows precise control of key reaction steps—inhibition, initiation, and propagation. Using an integrated computational and experimental framework, we uncover how near-equilibrium inhibition dynamics, coupled with far-from-equilibrium reaction kinetics, drive pattern formation in frontally polymerized synthetic materials. We propose the concept of equilibrium-gated pattern formation, demonstrating how initiator chemistry can be tuned to achieve programmable macroscale properties. Our study reveals a surprising insight: Emergent behavior in FROMP systems arises from the inhibition-dominated regime of resin composition, expanding prior observations that such behavior is confined to a narrow compositional space near the boundary between front quenching and uniform front propagation. We identify a broader compositional window, far from the quenching regime, where emergent behavior reliably manifests. This expanded design space significantly enhances the operational flexibility of reactive systems and their capacity for self-organization. Furthermore, these insights provide a roadmap for designing bioinspired materials with self-organizing capabilities, unlocking possibilities in synthetic manufacturing.

Architected Polymers↗
DOE OSTI2025

Thiol- and Disulfide-Functionalized Polycyclooctene: Metathesis Polymerization, Degradation, and Reformation

The enormous global production and use of polymers and plastics, combined with slower and less efficient disposal and recycling methods, have led to a worldwide growth in plastic waste. Here, we describe an approach that builds degradability into macromolecular polyolefins through the design of telechelic oligomers with reactive functional groups that enables control over polymer deconstruction and reconstruction. Our work exploits disulfide-containing polymers that have emerged as promising cyclable materials due to their dynamic reversibility (bond formation and cleavage) driven by redox chemistry under mild conditions. Specifically, we describe the synthesis of a telechelic α,ω-dithiopolycyclooctene (PCOE) by ring-opening metathesis polymerization using a dithioacetate chain transfer agent, followed by deprotection to convert the chain-end thioacetates to thiols. This process was studied towards control over the degree of oxidation to yield disulfide-containing PCOE, followed by an evaluation of reductive degradation and oxidative repolymerization. Overall, this approach facilitates the production of disulfide-containing unsaturated polyolefins and the integration of degradable and reformable moieties into soluble, processable, metathesis-derived polymers.

Lee, Kyoungwon↗
DOE OSTI2026

A Chemocatalytic Route to Stereoregular Poly(3-hydroxyhexanoate) and Its Statistical and Tri-Block Copolymers

Poly(3-hydroxyhexanoate) (P3HHx)-based poly(3- hydroxyalkanoate)s (PHAs) are biologically produced, commercially implemented PHAs, but little is known in the open literature about the structure and property characterizations of discrete, authentic homopolymer P3HHx, and its copolymers with poly(3- hydroxybutyrate) (P3HB). Here, we introduce a chemocatalytic route to stereoregular (both isotactic and syndiotactic) P3HHx and PHA copolymers with P3HB, including statistical copolymer P3HBHx with various levels of 3HHx incorporation and discrete hard−soft−hard triblock copolymer P3HB-b-P3HHx-b-P3HB, and present extensive characterizations of their structures, thermal properties, and mechanical performance. The synthesis is efficiently achieved by one-pot polymerization of eight-membered di(n-propyl) and dimethyl (for copolymerization) diolides catalyzed by chiral molecular catalysts. Notably, P3HBHx can be rapidly produced in quantitative yield and exhibits high molar mass (M n up to 551 kg/mol) as well as both high modulus (up to 1.39 GPa) and ductility (up to 445%), while P3HB-b-P3HHx-b-P3HB further extends application temperature windows by possessing a unique combination of low T g (−18 °C) and high T m (154 °C) values. These findings highlight the stereomicrostructural and architectural versatility of chemocatalytic routes to PHAs, which, in turn, can be utilized to largely tune the PHA thermal properties and mechanical performance.

Biopolymers↗
DOE OSTI2026

Positional Isomer of P3HB by Stereoselective Polymerization of Racemic α-Methyl-β-propiolactone Delivers Polyethylene-like Properties

Biobased and biodegradable poly(3-hydroxybutyrolactone) (P3HB) has long been considered as a more sustainable alternative to petroleum-based, nonbiodegradable polyolefins, but its properties are far off from its polyolefin (polyethylene, PE, and polypropylene, PP) counterpart’s unique set of thermal (low T g below −20 °C and high T m > 100 °C) and mechanical (high ductility >350%) characteristics. Here, we report that a positional isomer of P3HB, poly(3-hydroxy-2-methylpropionate) (P3H2MP), synthesized by catalyst-controlled stereoselective polymerization of racemic α-methyl-β-propiolactone, can match that demanding set of thermomechanical properties of PE. In particular, isotactic-rich P3H2MP, readily synthesized under ambient conditions, reaches high M n close to one million Da, T g down to −25 °C, T m up to 115 °C, tensile strength up to 64 MPa, and toughness up to 131 MJ m –3 , thus mechanically outperforming PE while maintaining a comparable low T g and high T m combination. A P3H2MP-based triblock copolymer further widens the low-high temperature window from T g = −29 °C to T m = 186 °C, resembling those of PP. These results show that P3H2MP exhibits the unique combination of thermomechanical properties matching those of high-performance polyolefins.

Biopolymers↗
DOE OSTI2023

A Self‐Healing System for Polydicyclopentadiene Thermosets

Self-healing offers promise for addressing structural failures, increasing lifespan, and improving durability in polymeric materials. Implementing self-healing in thermoset polymers faces significant manufacturing challenges, especially due to the elevated temperature requirements of thermoset processing. To introduce self-healing into structural thermosets, the self-healing system must be thermally stable and compatible with the thermoset chemistry. This article demonstrates a self-healing microcapsule-based system stable to frontal polymerization (FP), a rapid and energy-efficient manufacturing process with a self-propagating exothermic reaction (≈200 °C). A thermally latent Grubbs-type complex bearing two N-heterocyclic carbene ligands addresses limitations in conventional G2-based self-healing approaches. Under FP's elevated temperatures, the catalyst remains dormant until activated by a Cu(I) co-reagent, ensuring efficient polymerization of the dicyclopentadiene (DCPD) upon damage to the polyDCPD matrix. The two-part microcapsule system consists of one capsule containing the thermally latent Grubbs-type catalyst dissolved in the solvent, and another capsule containing a Cu(I) coagent blended with liquid DCPD monomer. Using the same chemistry for both matrix fabrication and healing results in strong interfaces as demonstrated by lap-shear tests. In an optimized system, the self-healing system restores the mechanical properties of the tough polyDCPD thermoset. Self-healing efficiencies greater than 90% via tapered double cantilever beam tests are observed.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Chemically Recyclable Analogs of Styrene–Butadiene Copolymers Enabling Perfectly Linear Ethylene–Styrene Materials with Random Phenyl Distribution

Copolymerization of cyclopentene (CP) and 4-phenylcyclopentene (4PCP) at a full range of comonomer feed ratios is reported using Ru-based ring-opening metathesis polymerization (ROMP) yielding homogeneous copolymers analogous to poly(styrene-ran-1,4-butadiene) and poly(ethylene-ran-styrene) copolymers following hydrogenation under mild conditions. In all cases, total monomer conversions of 86%–92% yielded copolymers with compositions within 4% of monomer feeds. Analysis of equilibrium copolymerization thermodynamics, rarely performed on two cycloolefin monomers with low ring strain energies, provides rational design strategies for negotiating two monomers with different equilibrium monomer concentrations. Inverse-gated decoupled 13 C NMR analysis of dyad sequences on the resulting copolymer microstructures concludes a near-random distribution of comonomer units. The copolymers produced from ROMP have number-average molar masses up to 60 kg mol –1 , moderate dispersities (1.5 ± 0.1), and high trans olefin content (86% ± 2%) while glass-transitions temperatures follow the Fox equation and span the full range between homopolymer extremities of PCP (−96 °C) and P4PCP (17 °C). Unlike most prevulcanized elastomers, these materials undergo facile chemical recycling to monomer, producing complete ring-closing metathesis depolymerization (RCMD) of the polymer back to the CP comonomers. Quantitative olefin hydrogenation produced perfectly linear polyethylene with 4%–16% of the backbone carbons containing a phenyl pendant, analogous to ES copolymers with up to 71.5% w/w styrene units but with random distribution of the aromatic pendants. Thermal properties of these materials are discussed, which span from semicrystalline to amorphous, and with T g values notably less than the reported ES copolymer analogs at similar compositions.

animal feed↗
DOE OSTI2026

B -Alkyl-borabicyclo[3.3.1]nonane Reagents Promote Closed-Shell Nickel-Catalyzed Alkylarylation Toward Encoded Cyclooctene Monomers

Access to new tailored monomers is essential to explore unprecedented polymer structures and modulate their properties. In previous work, we disclosed an iteroselective diarylation of 1,5-cyclooctadiene as an attractive platform for preparing diverse cyclooctene monomers; however, it was limited to C(sp 2 ) coupling partners. Established difunctionalization methods with C(sp 3 ) fragments rely on carbon-based radical formation, which is incompatible with 1,5-cyclooctadiene. This work describes a two-electron redox manifold for the nickel-catalyzed alkylarylation of 1,5-cyclooctadiene and discloses B -alkyl-borabicyclo[3.3.1]nonane (alkyl-9-BBN) as an effective transmetalating reagent for maintaining a polar reaction mechanism. The method provides 5,6-alkylarylated cyclooctenes suitable for ring-opening metathesis polymerization to obtain new materials. The properties of these polymers are benchmarked and fine-tuned by variation of coupling partners in the nickel catalysis. Density functional theory calculations revealed that destabilization of the pretransmetalation complex promotes the reactivity of alkyl-9-BBN in transmetalation compared to alkylboronic esters.

alkyls↗
DOE OSTI2026

FROMP-from-Monomer

This repository provides the 1D reaction-diffusion simulation engine for the multi-scale framework. It takes monomer-level kinetic and thermodynamic descriptors as inputs, approximated from quantum chemical calculations, to simulate and predict the macroscopic propagation behavior of Frontal Ring-Opening Metathesis Polymerization (FROMP). By solving a coupled 1D reaction-diffusion PDE system, this tool predicts front propagation speed, front temperature, and degree of conversion. The solver explicitly captures the three fundamental ROMP steps, initiator activation/inhibition, chain initiation, and propagation, while accounting for high-temperature cycloreversion as a competing pathway. The numerical implementation uses FEniCS to handle the coupled heat diffusion and reaction kinetics.

Chua, Lauren [Massachusetts Inst. of Technology (M↗
DOE OSTI2025

Catalytic Difunctionalization of Cyclic Dienes: Direct Entry to Novel ROMP Monomers

We developed a catalytic platform to convert simple hydrocarbon feedstocks into valuable, tunable materials by leveraging nickel-catalyzed difunctionalization of cyclic dienes to access a novel class of cyclic alkene monomers. These monomers undergo ring-opening metathesis polymerization (ROMP) to yield sequence-controlled polymers with defined stereochemistry. Through mechanistic studies and catalyst optimization, we established a scalable, gram-level synthesis for selective diarylation, and expanded the reaction scope to include arylalkylation through rationally tuning the organoboron coupling partner. The resulting polymers were systematically studied to understand how steric, electronic, and stereochemical features influence polymerization behavior and bulk material properties. Functionalized derivatives bearing sulfonated groups were explored as proton-exchange membranes, and chemical recycling pathways were developed to recover monomers from the final materials. This work bridges small-molecule catalysis and macromolecular design, enabling access to tunable, recyclable polymers from abundant hydrocarbon starting materials.

36 MATERIALS SCIENCE↗
NASA NTRS1988

Second and third order nonlinear optical properties of conjugated molecules and polymers

Second- and third-order nonlinear optical properties of some newly synthesized organic molecules and polymers are reported. Powder second-harmonic-generation efficiencies of up to 200 times urea have been realized for asymmetric donor-acceptor acetylenes. Third harmonic generation chi(3)s have been determined for a series of small conjugated molecules in solution. THG chi(3)s have also been determined for a series of soluble conjugated copolymers prepared using ring-opening metathesis polymerization. The results are discussed in terms of relevant molecular and/or macroscopic structural features of these conjugated organic materials.

Perry, Joseph W.↗
NASA NTRS2007

Norbornene-Based Polymer Electrolytes for Lithium Cells

Norbornene-based polymers have shown promise as solid electrolytes for lithium-based rechargeable electrochemical cells. These polymers are characterized as single-ion conductors. Single-ion-conducting polymers that can be used in lithium cells have long been sought. Single-ion conductors are preferred to multiple-ion conductors as solid electrolytes because concentration gradients associated with multiple-ion conduction lead to concentration polarization. By minimizing concentration polarization, one can enhance charge and discharge rates. Norbornene sulfonic acid esters have been synthesized by a ring-opening metathesis polymerization technique, using ruthenium-based catalysts. The resulting polymer structures (see figure) include sulfonate ionomers attached to the backbones of the polymer molecules. These molecules are single-ion conductors in that they conduct mobile Li+ ions only; the SO3 anions in these polymers, being tethered to the backbones, do not contribute to ionic conduction. This molecular system is especially attractive in that it is highly amenable to modification through functionalization of the backbone or copolymerization with various monomers. Polymers of this type have been blended with poly(ethylene oxide) to lend mechanical integrity to free-standing films, and the films have been fabricated into solid polymer electrolytes. These electrolytes have been demonstrated to exhibit conductivity of 2 10(exp -5)S/cm (which is high, relative to the conductivities of other solid electrolytes) at ambient temperature, plus acceptably high stability. This type of norbornene-based polymeric solid electrolyte is in the early stages of development. Inasmuch as the method of synthesis of these polymers is inherently flexible and techniques for the fabrication of the polymers into solid electrolytes are amenable to optimization, there is reason to anticipate further improvements.

Cheung, Iris↗