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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Solution Blowing Synthesis of Li-Conductive Ceramic Nanofibers

Solid state electrolytes (SSEs) offer great potential to enable high-performance and safe lithium (Li) batteries. However, the scale-up synthesis and processing of SSEs is a major challenge. In this work, three-dimensional networks of lithium lanthanum titanite (LLTO) nanofibers are produced through a scale-up technique based on solution blowing. Compared with the conventional electrospinning method, the solution blowing technique enables high-speed fabrication of SSEs (e.g., 15 times faster) with superior productivity and quality. Additionally, the room-temperature ionic conductivity of composite polymer electrolytes (CPEs) formed from solution-blown LLTO fibers is 70% higher than the ones formed from electrospun fibers (1.9 x 10 -4 vs 1.1 x 10 -4 S cm -1 for 10 wt % LLTO fibers). Furthermore, the cyclability of the CPEs made from solution-blown fibers in the symmetric Li cell is more than 2.5 times that of the CPEs made from electrospun fibers. These comparisons here show that solution-blown ion-conductive fibers hold great promise for applications in Li metal batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Effects of Concentration, Salinity and Temperature on the Conformations of Zwitterionic Poly(2-Vinylpyridine- N -Oxide) Chains in Semidilute Solutions Probed by Small-Angle X-Ray and Neutron Scattering

Polyzwitterions, composed of repeating units with equal numbers of anionic and cationic groups, have drawn considerable interest for applications ranging from antimicrobial coatings and antifouling membranes to low-friction interfaces, energy storage media, and actuators. A characteristic feature of many polyzwitterions is the anti-polyelectrolyte effect salt-induced chain expansion in aqueous solution a phenomenon often implicated in their functional behavior. In this study, we investigated the conformational behavior of poly(2-vinylpyridine-N-oxide) (P2VPNO) using smallangle X-ray and neutron scattering (SAXS and SANS). Small-angle X-ray scattering (SAXS) revealed that, in salt-free aqueous solution, P2VPNO adopts an expanded wormlike conformation stabilized by hydration. With increasing concentration, the chains contract due to screening of intrachain excluded-volume interactions, qualitatively consistent with de Gennes’ scaling predictions for neutral polymers. Small-angle neutron scattering (SANS) further demonstrated that P2VPNO exhibits the characteristic anti-polyelectrolyte response to added salt, as observed in many other polyzwitterions. At elevated temperatures, chain flexibility increases, leading to a shorter Kuhn length and reduced radius of gyration. Notably, however, salt-induced chain expansion persists, indicating that the anti-polyelectrolyte effect remains operative under elevated thermal conditions. These findings provide the first experimental evidence of scaling behavior in polyzwitterions, as well as the first observation of their altered antipolyelectrolyte response at elevated temperatures, offering new insights into the solution physics of this important class of polymers.

Conformation↗
DOE OSTI2021

Boric acid removal with polyol-functionalized polyether membranes

Poor selectivity of conventional desalination membranes for boron often necessitates multi-stage treatment trains to achieve desired boron removal for end uses such as irrigation. One approach to membrane design for improved single-pass boric acid removal is via incorporation of chelating ligands that selectively sorb boron. In this study, membranes based on epoxy-amine cross-linked poly(glycidyl glycidyl ether) (PGGE) were synthesized and functionalized with N-methyl-d-glucamine (NMDG), a polyol known to interact selectively with boron. PGGE and PGGE-NMDG membranes exhibited boron sorption isotherms that were well-described by dual mode isotherms. PGGE-NMDG sorbed 2.5 mmol B/g dry polymer from a neutral aqueous solution containing 100 mmol B/L, which was almost three times the adsorption density of a commercial boron selective resin, Amberlite IRA743. Further, the membranes were regenerated in acid without a significant loss of boron sorption capacity over four cycles. Interactions between boron and NMDG and PGGE sites (e.g., epoxides) impacted boron diffusion in both membranes. The use of ligand functionalized membranes to capture target solutes such as boron requires high loading of interacting sites to maximize uptake capacity. Establishing fundamental structure/property rules for boron selectivity could lead to new material designs with improved boron separation properties for water purification.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Controlling Polymer Morphology in Blade-Coated All-Polymer Solar Cells

In this report translating all-polymer solar cells from spin-coating to scalable roll-to-roll-compatible fabrication techniques is a critical step toward the application of organic photovoltaics at a scale. Techniques to control polymer crystallization and phase separation during solution printing are essential to obtain high-performance printed organic solar cells. Here, we demonstrate a novel solvent additive approach employing trace amounts of phthalates as additives to control polymer crystallinity and suppress unfavorable phase separation in a representative PTB7-Th/P(NDI2OD-2T) all-polymer solar cell. The best-performing additive increased the blade-coated device performance from 2.09 to 4.50% power conversion efficiency, an over twofold improvement, mitigating the loss in performance that is typically observed during process transfer from spin-coating to blade-coating. It is suggested that the improved device performance stems from a finer polymer phase-separation size and overall improved active layer morphology, evidenced by device characterization data and indirectly supported by grazing incidence wide-angle X-ray scattering analyses. Real-time X-ray diffraction measurements during blade-coating provide mechanistic insights and suggest that the dioctyl phthalate additive may act as a compatibilizer, reducing the demixing of the donor and acceptor polymer during film formation, enabling a smaller phase separation and improved performance. The structural diversity of the class of phthalate additives makes this simple yet effective concept promising for translating other all-polymer material systems to blade-coating and other scalable printing techniques.

14 SOLAR ENERGY↗
DOE OSTI2024

3D Printing of Functional Hydrogel Devices for Screenings of Membrane Permeability and Selectivity

Developing a fundamental understanding of the effects of varying ligand chemistries on mass transport rates is key to designing membranes with solute-specific selectivity. While permeation cells offer a robust method to characterize membrane performance, they are limited to assessing a single membrane chemistry or salt solution per test. As a result, investigating the effects of varying ligand chemistries on membrane performance can be a tedious process, involving both the preparation of multiple samples and numerous, time-consuming permeation tests. This study uses digital light processing (DLP) 3D printing to fabricate a millifluidic flow-based permeation device made from a hydrogel active ester network that can be easily functionalized with ion-selective ligands. Without the need for bonding or assembly steps, ligands can be introduced and tested in the permeation device by simply injecting a small volume of a ligand solution. Various salt concentrations and molecular species can be cycled through a single device by switching the solution feeding into the salt reservoir, thereby reducing the number of samples needed for permeability and selectivity screenings. This research sets the groundwork for formulation development and postprocessing methods to 3D-print functional millifluidic devices capable of assessing solute selectivity in membranes and polymer adsorbents for aqueous separations. In this work, comparable salt permeability trends were observed with both 3D-printed devices and traditional assays. Devices were functionalized with an imidazole ligand to investigate salt permeability and selectivity of monovalent and divalent salts. Measurements showed increasing permeability for monovalent salts (NaCl) relative to divalent salts (MgCl 2 , CuCl 2 ) in functionalized membranes, with higher monovalent/divalent selectivity at increasing imidazole grafting densities. Here, the methods and findings described here represent a step toward developing higher-throughput methods with 3D-printed devices for screening the effects of ligand chemistry on mass transport rates in membrane materials.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Mapping the Morphology of DNA on Carbon Nanotubes in Solution Using X-ray Scattering Interferometry

Single-walled carbon nanotubes (SWCNTs) with adsorbed single-stranded DNA (ssDNA) are applied as sensors to investigate biological systems, with potential applications ranging from clinical diagnostics to agricultural biotechnology. Unique ssDNA sequences render SWCNTs selectively responsive to target analytes such as (GT)n-SWCNTs recognizing the neuromodulator, dopamine. It remains unclear how the ssDNA conformation on the SWCNT surface contributes to functionality, as observations have been limited to computational models or experiments under dehydrated conditions that differ substantially from the aqueous biological environments in which the nanosensors are applied. We demonstrate a direct mode of measuring in-solution ssDNA geometries on SWCNTs via X-ray scattering interferometry (XSI), which leverages the interference pattern produced by AuNP tags conjugated to ssDNA on the SWCNT surface. We employ XSI to quantify distinct surface-adsorbed morphologies for two (GT) n ssDNA oligomer lengths (n = 6, 15) that are used on SWCNTs in the context of dopamine sensing and measure the ssDNA conformational changes as a function of ionic strength and during dopamine interaction. Here, we show that the shorter oligomer, (GT) 6 , adopts a more periodically ordered ring structure along the SWCNT axis (inter-ssDNA distance of 8.6 ± 0.3 nm), compared to the longer (GT) 15 oligomer (most probable 5'-to-5' distance of 14.3 ± 1.1 nm). During molecular recognition, XSI reveals that dopamine elicits simultaneous axial elongation and radial constriction of adsorbed ssDNA on the SWCNT surface. Our approach using XSI to probe solution-phase morphologies of polymer-functionalized SWCNTs can be applied to yield insights into sensing mechanisms and inform future design strategies for nanoparticle-based sensors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Hybrid gels via bulk interfacial complexation of supramolecular polymers and polyelectrolytes

Hierarchical self-assembly leading to organized supramolecular structures across multiple length scales has been of great recent interest. Earlier work from our laboratory reported the complexation of peptide amphiphile (PA) supramolecular polymers with oppositely charged polyelectrolytes into a single solid membrane at a macroscopic interface. We report here the formation of bulk gels with many internal interfaces between the covalent and supramolecular polymer components formed by the rapid chaotic mixing of solutions, one containing negatively charged PA nanofibers and the other the positively charged biopolymer chitosan. We found that formation of a contact layer at the interface of the solutions locks the formation of hydrogels with lamellar microstructure. The nanofiber morphology of the supramolecular polymer is essential to this process since gels do not form when solutions of supramolecular assemblies form spherical micelles. Here, we found that rheological properties of the gels can be tuned by changing the relative amounts of each component. Furthermore, both positively and negatively charged proteins are easily encapsulated within the contact layer of the gel, which provides an interesting biomedical function for these systems.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Polymers in direct air capture: a mini review

The urgent need to mitigate climate change has intensified interest in direct air capture (DAC) technology, which targets extracting carbon dioxide (CO2) directly from the atmosphere. Among the various sorbents used in DAC, polymers have emerged as a promising solution, either as active sorbents or as structural supports for active DAC materials, due to their customizable properties, scalability and low cost. This mini-review investigates the latest trends in polymer-based materials for DAC and identifies critical research gaps, such as the need for thorough lifecycle assessments and in-depth studies on the degradation of polymeric materials. It also outlines future directions, emphasizing the importance of developing cost-effective, scalable and durable polymers that can perform efficiently across diverse climatic conditions, including the unique challenges presented by cold weather regions abundant in renewable energy. This mini-review aims to inform ongoing efforts in the design and utilization of polymeric sorbents, providing insights that could guide the development of economically viable and environmentally sustainable DAC technologies.

climate change↗
DOE OSTI2024

Catalytic, Spectroscopic, and Theoretical Studies of Fe 4 S 4 -Based Coordination Polymers as Heterogenous Coupled Proton–Electron Transfer Mediators for Electrocatalysis

Iron–sulfur clusters play essential roles in biological systems, and thus synthetic [Fe 4 S 4 ] clusters have been an area of active research. Recent studies have demonstrated that soluble [Fe 4 S 4 ] clusters can serve as net H atom transfer mediators, improving the activity and selectivity of a homogeneous Mn CO 2 reduction catalyst. Here, in this work, we demonstrate that incorporating these [Fe 4 S 4 ] clusters into a coordination polymer enables heterogeneous H atom transfer from an electrode surface to a Mn complex dissolved in solution. A previously reported solution-processable Fe 4 S 4 -based coordination polymer was successfully deposited on the surfaces of different electrodes. The coated electrodes serve as H atom transfer mediators to a soluble Mn CO 2 reduction catalyst displaying good product selectivity for formic acid. Furthermore, these electrodes are recyclable with a minimal decrease in activity after multiple catalytic cycles. The heterogenization of the mediator also enables the characterization of solution-phase and electrode surface species separately. Surface enhanced infrared absorption spectroscopy (SEIRAS) reveals spectroscopic signatures for an in situ generated active Mn–H species, providing a more complete mechanistic picture for this system. The active species, reaction mechanism, and the protonation sites on the [Fe 4 S 4 ] clusters were further confirmed by density functional theory calculations. The observed H atom transfer reactivity of these coordination polymer-coated electrodes motivates additional applications of this composite material in reductive H atom transfer electrocatalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Making Plasticized Polymer Electrolytes Stable Against Sodium Metal for High‐Energy Solid‐State Sodium Batteries

Solid polymer electrolytes based on plastic crystals are promising for solid-state sodium metal (Na 0 ) batteries, yet their practicality has been hindered by the notorious Na 0 -electrolyte interface instability issue, the underlying cause of which remains poorly understood. Here, in this study, by leveraging a model plasticized polymer electrolyte based on conventional succinonitrile plastic crystals, we uncover its failure origin in Na 0 batteries is associated with the formation of a thick and non-uniform solid electrolyte interphase (SEI) and whiskery Na 0 nucleation/growth. Furthermore, we design a new additive-embedded plasticized polymer electrolyte to manipulate the Na 0 deposition and SEI formulation. For the first time, we demonstrate that introducing fluoroethylene carbonate (FEC) additive into the succinonitrile-plasticized polymer electrolyte can effectively protect Na 0 against interfacial corrosion by facilitating the growth of dome-like Na 0 with thin, amorphous, and fluorine-rich SEIs, thus enabling significantly improved performances of Na//Na symmetric cells (1,800 h at 0.5 mA cm −2 ) and Na//Na 3 V 2 (PO 4 ) 3 full cells (93.0 % capacity retention after 1,200 cycles at 1 C rate in coin cells and 93.1 % capacity retention after 250 cycles at C/3 in pouch cells at room temperature). Our work provides valuable insights into the interfacial failure of plasticized polymer electrolytes and offers a promising solution to resolving the interfacial instability issue.

25 ENERGY STORAGE↗
DOE OSTI2022

Designing polymeric membranes with coordination chemistry for high-precision ion separations

State-of-the-art polymeric membranes are unable to perform the high-precision ion separations needed for technologies essential to a circular economy and clean energy future. Coordinative interactions are a mechanism to increase sorption of a target species into a membrane, but the effects of these interactions on membrane permeability and selectivity are poorly understood. We use a multilayered polymer membrane to assess how ion-membrane binding energies affect membrane permeability of similarly sized cations: Cu 2+ , Ni 2+ , Zn 2+ , Co 2+ , and Mg 2+ . We report that metals with higher binding energy to iminodiacetate groups of the polymer more selectively permeate through the membrane in multisalt solutions than single-salt solutions. In contrast, weaker binding species are precluded from diffusing into the polymer membrane, which leads to passage proportional to binding energy and independent of membrane thickness. Our findings demonstrate that selectivity of polymeric membranes can markedly increase by tailoring ion-membrane binding energy and minimizing membrane thickness.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Transport Mechanisms of Hydrogen Gas and Ions in Poly(potassium acrylate) Electrolytes

Poly(potassium acrylate) (PAAK) in high concentration KOH solutions is a promising electrolyte for use in alkaline zinc batteries. Atomistic molecular dynamics simulations are used to investigate the transport mechanisms of hydrogen gas and zincate ions through both KOH solutions and PAAK solutions with comparable concentrations of KOH. Hydrogen molecules do not interact with the ions or the polymer, and simply diffuse through the system. Furthermore, their diffusion constant decreases with both increasing KOH concentration and when in the polymer, due to the increased viscosity of the solution. By contrast, zincate ions form long-lived clusters with the PAAK chains which significantly slow their diffusion.

Batteries↗
DOE OSTI2024

Polymers depolymerizable by metathesis of a cleavable unit

Novel polymers are depolymerizable by metathesis of a cleavable unit. As an example, a series of linear and crosslinked polyurethanes were prepared that can be selectively depolymerized under mild conditions. Two unique polyols were synthesized bearing unsaturated units in a configuration designed to favor ring-closing metathesis to five- and six-membered cycloalkenes. These polyols were co-polymerized with toluene diisocyanate to generate linear polyurethanes and trifunctional hexamethylene- and diphenylmethane-based isocyanates to generate crosslinked polyurethanes. The polyol design is such that the ring-closing metathesis reaction cleaves the backbone of the polymer chain. Upon exposure to dilute solutions of Grubbs' catalyst under ambient conditions, the polyurethanes were rapidly depolymerized to low molecular weight, soluble products bearing vinyl and cycloalkene functionalities. These functionalities enabled further re-polymerization by traditional strategies for polymerization of double bonds. This general approach can be expanded to develop a range of chemically recyclable condensation polymers that are readily depolymerized by orthogonal metathesis chemistry.

Jones, Brad Howard↗
DOE OSTI2025

Preprocessing Affords 3D Crystalline Poly(3-hexylthiophene) Structure

The aggregation and crystallization of poly(3-hexylthiophene- 2,5-diyl) (P3HT), a representative active layer material used for organic field-effect transistor (OFET) applications, are influenced by the solution pretreatment and deposition process. This study explores vibration-assisted convective deposition for the fabrication of OFETs in comparison to spin coating, blade coating, and convective deposition without vibration. The ultraviolet–visible spectroscopic analysis demonstrates that convective deposition, especially assisted with vibration, leads to a greater degree of intrachain interactions, longer conjugation length, and enhanced polymer backbone planarization. When the P3HT solution is preprocessed via sonication and aging, the P3HT films exhibit J-like aggregation, and (h11) peaks can be observed through grazing-incidence wide-angle X-ray scattering, suggesting an ordered 3D crystalline structure. OFETs based on such films exhibit high mobilities (up to 0.14 cm 2 V –1 s –1 ). The results point to the sensitivity of P3HT charge transport behavior to the intramolecular interactions and backbone planarity and further deepen our understanding of the relationship between processing, aggregates, molecular ordering, and resultant device properties.

36 MATERIALS SCIENCE↗
DOE OSTI2024

A Three-in-One Hybrid Strategy for High-Performance Semiconducting Polymers Processed from Anisole

The development of semiconducting polymers with good processability in green solvents and competitive electrical performance is essential for realizing sustainable large-scale manufacturing and commercialization of organic electronics. A major obstacle is the processability-performance dichotomy that is dictated by the lack of ideal building blocks with balanced polarity, solubility, electronic structures, and molecular conformation. Herein, through the integration of donor, quinoid and acceptor units, an unprecedented building block, namely TQBT, is introduced for constructing a serial of conjugated polymers. The TQBT, distinct in non-symmetric structure and high dipole moment, imparts enhanced solubility in anisole—a green solvent—to the polymer TQBT-T. Furthermore, PTQBT-T possess a highly rigid and planar backbone owing to the nearly coplanar geometry and quinoidal nature of TQBT, resulting in strong aggregation in solution and localized aggregates in film. Remarkably, PTQBT-T films spuncast from anisole exhibit a hole mobility of 2.30 cm 2 V -1 s -1 , which is record high for green solvent-processable semiconducting polymers via spin-coating, together with commendable operational and storage stability. The hybrid building block emerges as a pioneering electroactive unit, shedding light on future design strategies in high-performance semiconducting polymers compatible with green processing and marking a significant stride towards ecofriendly organic electronics.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Selectively Depolymerizable Polyurethanes from Unsaturated Polyols Cleavable by Olefin Metathesis

This communication describes a novel series of linear and crosslinked polyurethanes (PUs) and their selective depolymerization under mild conditions. Two unique polyols are synthesized bearing unsaturated units in a configuration designed to favor ring-closing metathesis (RCM) to five- and six-membered cycloalkenes. These polyols are co-polymerized with toluene diisocyanate to generate linear PUs and trifunctional hexamethylene- and diphenylmethane-based isocyanates to generate crosslinked PUs. The polyol design is such that the RCM reaction cleaves the backbone of the polymer chain. Upon exposure to dilute solutions of Grubbs’ catalyst under ambient conditions, the PUs are rapidly depolymerized to low molecular weight, soluble products bearing vinyl and cycloalkene functionalities. These functionalities enable further re-polymerization by traditional strategies for polymerization of double bonds. We anticipate that this general approach can be expanded to develop a range of chemically recyclable condensation polymers that are readily depolymerized by orthogonal metathesis chemistry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Solid-State Side-Chain Functionalization of Conjugated Polymers for Expanded Chemical and Functional Versatility

Conjugated polymers that integrate diverse chemical functionalities with high electronic performance are essential for advanced organic electronic, optoelectronic, and biointerfaced technologies. Achieving such multifunctionality typically requires grafting functional units onto polymer side chains. However, conventional solution-phase approaches remain constrained by solubility limitations, side-chain-induced packing disruptions, and challenges in preserving charge transport. Here, we introduce a solid-state side-chain functionalization strategy that exploits a swellable polar side-chain architecture and azide–alkyne click chemistry to enable efficient molecular diffusion and reaction throughout predeposited polymer thin films. This approach substantially broadens the chemical compatibility of graftable units and mitigates the adverse effects on the electrical property. Moreover, the method supports spatially selective functionalization within a continuous film, enabling the patterned incorporation of chemically distinct groups to produce spatially defined optical properties. Here, this solid-state strategy thus provides a versatile platform for constructing conjugated polymers with expanded chemical versatility, preserved electronic performance, and programmable spatial functionality.

Conjugated polymers↗