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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Understanding and Developing Dual-Wavelength Olefin Metathesis Polymerizations for the Rapid, Continuous Additive Manufacturing of High-Performance Thermosets

This report details the goals, approach, results, and future needs of a three-year Laboratory Directed Research and Development project funded by Sandia’s Materials Science Research Foundation. In this project, we established basic principles and mechanistic understanding of orthogonal or sequential chemistries for fabricating multi-material or robust materials. We developed numerous additive manufacturing, or 3D-printing, techniques including volumetric solid-state printing, dual-wavelength printing, and lithographic regulation of polymer crystallinity. We leveraged these new printing motifs to expand upon what is possible with manufacturing to give bespoke optical and mechanical performance. Moreover, we discovered new techniques for depolymerization enabling recovery of pristine carbon-fiber and high value electronics under moderate conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Control of polymer architectures by living ring-opening metathesis copolymerization

In an aspect, a method of synthesizing a graft copolymer comprises the steps of: copolymerizing a first macromonomer and a first reactive diluent; wherein said first macromonomer comprises a first backbone precursor directly or indirectly covalently linked to a first polymer side chain group; wherein said reactive diluent is provided in the presence of the first macromonomer at an amount selected so as to result in formation said graft copolymer having a first backbone incorporating said diluent and said first macromonomer in a first polymer block characterized by a preselected first graft density or a preselected first graft distribution of said first macromonomer. In some embodiments of this aspect, said preselected first graft density is any value selected from the range of 0.05 to 0.75. In some methods, the composition and amount of said diluent is selected to provide both a first preselected first graft density and a first preselected first graft distribution.

Grubbs, Robert H.↗
DOE OSTI2025

Toward Efficient Entropic Recycling by Mastering Ring–Chain Kinetics

Traditional chemical recycling approaches for condensation polymers suffer compounding energy losses and CO 2 emissions across multiple polymerization and depolymerization cycles. Entropic recycling can address these energy losses by entrapping free energy within the deconstruction products. Entropic recycling involves depolymerization to macrocyclic monomers, but such processes have not been feasible due to the high dilutions typically required to generate macrocyclic compounds. Here, we leverage selective catalysis to allow entropic recycling at concentrations 20–2000× higher than typical for macrocyclization reactions. We find that Ru-based olefin metathesis catalysts containing bulky iodine ligands significantly bias the ring–chain kinetic product distribution during ring-closing metathesis (RCM) toward the formation of oligomeric cycloalkenes. Further improvements in reaction concentration and macrocycle yield are obtained by using high catalyst loadings and by predisposing the alkene substrates to undergo favorable macrocyclization. These RCM optimizations translate effectively to cyclodepolymerization (CDP) of an olefin-containing polymer, with RCM and CDP affording similar macrocycle product distributions under identical reaction conditions. Macrocycle polymerization by entropy-driven ring-opening metathesis provides much higher molecular weight polymers than condensation polymerization of linear analogues, reducing the time to achieve high molecular weight from hours to minutes and enabling polymerization at room temperature. Finally, our findings re-emphasize the importance of energy consumption during a polymer’s lifecycle and provide a framework for the design of efficient entropic recycling systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Scalable Frontal Oligomerization: Insights from Advanced Mass Analysis

Linear oligomers of dicyclopentadiene (DCPD) are reactive precursors for thermoplastic and thermoset materials. Unlike the foul-smelling parent monomer, oligomers composed of DCPD are odorless. With appropriate modification of the end-group or backbone chemistry, telechelic DCPD oligomers have potential utility as cross-linkers and as macromonomer precursors for block and graft copolymers. Most existing methods to produce oligo-DCPD, however, require solvent, are relatively slow, and necessitate air-free techniques. Here we show that frontal ring-opening metathesis oligomerization (FROMO) of neat DCPD and other norbornene derivatives rapidly generates hundreds of grams of material in minutes with catalyst loadings of 0.5 mM. This energy-efficient catalytic process utilizes the heat generated by the reaction to self-propagate oligomerization throughout the liquid monomer. FROMO employs a terminal olefin (e.g., styrene) in which a cross-metathesis reaction (i.e., chain transfer) competes with ring-opening metathesis (i.e., propagation). Kendrick mass analysis enables rapid identification and assignment of all the chain-end types present and quantifies the degree of branching resulting from the infrequent cyclopentene ring-opening reaction. This analytical technique also detects oligomer species derived from trace impurities in the monomer or chain-transfer agent that are otherwise difficult to observe with other characterization methods. Here, the obtained oligomers possess well-defined chain-ends and molecular weight distributions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗