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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 883 records · Page 49
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Lignin-Graft-Poly(lactic- co -glycolic) Acid Biopolymers for Polymeric Nanoparticle Synthesis

A lignin-graft-poly(lactic- co -glycolic) acid (PLGA) biopolymer was synthesized with two types of lignin (LGN), alkaline lignin (ALGN) and sodium lignosulfonate (SLGN), at different (A/S)LGN/PLGA ratios (1:2, 1:4, and 1:6 w/w). 1 H NMR and Fourier-transform infrared spectroscopy (FT-IR) confirmed the conjugation of PLGA to LGN. The (A/S)LGN-graft-PLGA biopolymers were used to form nanodelivery systems suitable for entrapment and delivery of drugs for disease treatment. The LGN-graft-PLGA NPs were generally small (100–200 nm), increased in size with the amount of PLGA added, monodisperse, and negatively charged (-48 to -60 mV). Small-angle scattering data showed that particles feature a relatively smooth surface and a compact spherical structure with a distinct core and a shell. The core size and shell thickness varied with the LGN/PLGA ratio, and at a 1:6 ratio, the particles deviated from the core–shell structure to a complex internal structure. The newly developed (A/S)LGN-graft-PLGA NPs are proposed as a potential delivery system for applications in biopharmaceutical, food, and agricultural sectors.

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

Production and Purification of Terbium-155 Using Natural Gadolinium Targets

Terbium-155 (t 1/2 = 5.32 days) is one of four medically relevant radioisotopes of terbium. It is of interest to the field as a suitable diagnostic counterpart for therapeutic radiolanthanides, as its decay scheme includes γ-rays that are suitable for single photon emission computed tomography (SPECT) imaging. Additionally, 155 Tb has an Auger electron (AE) yield that is viable for AE therapy. There are several direct and indirect production routes that can produce 155 Tb. Two possible direct routes include proton irradiation on gadolinium targets via 155 Gd(p,n) 155 Tb and 156 Gd(p,2n) 155 Tb. The 155 Gd(p,n) 155 Tb reaction is accessible at incident proton beam energies of ∼10 MeV, whereas the 156 Gd(p,2n) 155 Tb nuclear reaction requires ∼18 MeV. This study aims to investigate the production of 155 Tb from natGd through the nat Gd(p,x) nuclear reaction, wherein both (p,n) and (p,2n) reactions were leveraged, and the purification using a three-column ion chromatography method. Using this system, recoveries of radioterbium of up to 97% were achieved in addition to high recoveries of the Gd target material, illustrating the suitability of this technique for enriched targets.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Direct Extraction of Uniform Lignin Microspheres from Bamboo Using a Polyol-Based Deep Eutectic Solvent

Conventional preparation of lignin micro-/nano-particles (LMNPs) often needs multiple steps accompanied by high cost, low efficiency, and low yield. Herein, this study established a polyhydric alcohol-based deep eutectic solvent (PA-DES) fractionation for direct LMNP assembly from raw lignocellulose. The results indicated that lignin was significantly extracted by 41.55–70.33% depending on the PA-DES varieties. With lignin removal, the substrate showed high glucan enzymatic saccharification from 70.44 to 100%. Specially, over 90% lignin could be recovered in each PA-DES, and the obtained LMNPs showed quite uniform spherical morphology with a tunable size of 550–3254 nm and narrow polydispersity index (PDI) of 0.295–0.398. The proposed DES showed a near theoretical recovery yield, which still featured excellent fractionation performance even after three cycles of reuse. In conclusion, the findings highlight the simultaneous utilization of cellulose and lignin in a one-pot biomass fractionation under mild conditions with sugars and LMNPs as the coproducts.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Elucidating Quintet-State Dynamics in Singlet Fission Oligomers and Polymers with Tetracene Pendants

To unlock the potential of molecular engineering for practical quantum sensing and computing, it is essential to create and control pure magnetic states in molecular systems. Singlet fission (SF) in organic materials offers a promising approach by generating pairs of triplet excited states from photoexcited singlets. Here, in this work, we investigate SF in a polymer with strategically positioned tetracene pendant groups along a polynorbornene backbone and its oligomeric counterparts, facilitating intrapolymer through-space coupling. Using continuous-wave and pulsed time-resolved electron paramagnetic resonance (EPR) spectroscopy, we elucidate the spin dynamics and identify key intermediates, including the quintet state, that emerge during SF. Our findings reveal that exciton translational motion along the pendant groups enhances the dissociation of triplet pairs, with oligomer length playing a critical role in modulating spin state interconversion and exciton transport. Our results provide key insights into the SF mechanism in polymeric materials and highlight the role of oligomer length in modulating spin state interconversion and exciton transport. This work advances our understanding of SF in polymers, paving the way for their application in quantum information science and energy conversion technologies.

Bindra, Jasleen K. [Argonne National Laboratory (A↗
DOE OSTI2021

SMART transfer method to directly compare the mechanical response of water-supported and free-standing ultrathin polymeric films

Abstract Intrinsic mechanical properties of sub-100 nm thin films are markedly difficult to obtain, yet an ever-growing necessity for emerging fields such as soft organic electronics. To complicate matters, the interfacial contribution plays a major role in such thin films and is often unexplored despite supporting substrates being a main component in current metrologies. Here we present the shear motion assisted robust transfer technique for fabricating free-standing sub-100 nm films and measuring their inherent structural–mechanical properties. We compare these results to water-supported measurements, exploring two phenomena: 1) The influence of confinement on mechanics and 2) the role of water on the mechanical properties of hydrophobic films. Upon confinement, polystyrene films exhibit increased strain at failure, and reduced yield stress, while modulus is reduced only for the thinnest 19 nm film. Water measurements demonstrate subtle differences in mechanics which we elucidate using quartz crystal microbalance and neutron reflectometry.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Soft elasticity optimises dissipation in 3D-printed liquid crystal elastomers

Soft-elasticity in monodomain liquid crystal elastomers (LCEs) is promising for impact-absorbing applications where strain energy is ideally absorbed at constant stress. Conventionally, compressive and impact studies on LCEs have not been performed given the notorious difficulty synthesizing sufficiently large monodomain devices. Here, we use direct-ink writing 3D printing to fabricate bulk (>cm 3 ) monodomain LCE devices and study their compressive soft-elasticity over 8 decades of strain rate. At quasi-static rates, the monodomain soft-elastic LCE dissipated 45% of strain energy while comparator materials dissipated less than 20%. At strain rates up to 3000 s –1 , our soft-elastic monodomain LCE consistently performed closest to an ideal-impact absorber. Drop testing reveals soft-elasticity as a likely mechanism for effectively reducing the severity of impacts – with soft elastic LCEs offering a Gadd Severity Index 40% lower than a comparable isotropic elastomer. Lastly, we demonstrate tailoring deformation and buckling behavior in monodomain LCEs via the printed director orientation.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Medial packing and elastic asymmetry stabilize the double-gyroid in block copolymers

Triply-periodic networks are among the most complex and functionally valuable self-assembled morphologies, yet they form in nearly every class of biological and synthetic soft matter building blocks. In contrast to simpler assembly motifs – spheres, cylinders, layers – networks require molecules to occupy variable local environments, confounding attempts to understand their formation. Here, we examine the double-gyroid network phase by using a geometric formulation of the strong stretching theory of block copolymer melts, a prototypical soft self-assembly system. The theory establishes the direct link between molecular packing, assembly thermodynamics and the medial map, a generic measure of the geometric center of complex shapes. We show that “medial packing” is essential for stability of double-gyroid in strongly-segregated melts, reconciling a long-standing contradiction between infinite- and finite-segregation theories. Additionally, we find a previously unrecognized non-monotonic dependence of network stability on the relative entropic elastic stiffness of matrix-forming to tubular-network forming blocks. The composition window of stable double-gyroid widens for both large and small elastic asymmetry, contradicting intuitive notions that packing frustration is localized to the tubular domains. This study demonstrates the utility of optimized medial tessellations for understanding soft-molecular assembly and packing frustration via an approach that is readily generalizable far beyond gyroids in neat block copolymers.

36 MATERIALS SCIENCE↗
DOE OSTI2023

DNA-caged nanoparticles via electrostatic self-assembly

DNA-modified nanoparticles enable DNA sensing and therapeutics in nanomedicine and are also crucial for nanoparticle self-assembly with DNA-based materials. However, methods to conjugate DNA to nanoparticle surfaces are limited, inefficient, and lack control. Inspired by DNA tile nanotechnology, we demonstrate a new approach to nanoparticle modification based on electrostatic attraction between negatively charged DNA tiles and positively charged nanoparticles. This approach does not disrupt nanoparticle surfaces and leverages the programmability of DNA nanotechnology to control DNA presentation. We demonstrated this approach using a variety of nanoparticles, including polymeric micelles, polystyrene beads, gold nanoparticles, and superparamagnetic iron oxide nanoparticles with sizes ranging from 5–20 nm in diameter. DNA cage formation was confirmed through transmission electron microscopy (TEM), neutralization of zeta potential, and a series of fluorescence experiments. DNA cages present “handle” sequences that can be used for reversible target attachment or self-assembly. Handle functionality was verified in solution, at the solid–liquid interface, and inside fixed cells, corresponding to applications in biosensing, DNA microarrays, and erasable immunocytochemistry. Finally, these experiments demonstrate the versatility of the electrostatic DNA caging approach and provide a new pathway to nanoparticle modification with DNA that will empower further applications of these materials in medicine and materials science.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Experimental Comparison of Elastomeric Materials for Hydraulic Seal Durability under Reciprocating Conditions

Wave Energy Converters (WECs) rely on hydraulic Power Take-Off (PTO) systems to transform the kinetic energy of ocean waves into electricity, where hydraulic seals play a critical role in preventing fluid leakage and ensuring watertight operation under harsh marine conditions. However, seal degradation due to wear, fatigue, and corrosion remains a key challenge limiting system reliability and increasing maintenance costs. In this study, the tribological performance of elastomeric materials for hydraulic sealing applications that are based on commercial polyurethane and custom-compounded Ethylene Propylene Diene Monomer (EPDM) is investigated. Using a CSM tribometer, reciprocating wear tests were conducted in accordance with ASTM G133 under dry sliding conditions, with normal loads ranging from 3 to 10 N, and sliding speeds of 10 to 30 mm/s. Coefficient of friction (COF), specific wear rate, and worn surface morphology are evaluated to understand how load, velocity, and material composition affect seal durability. Improved wear stability and high Shore A hardness (93–94) were demonstrated by the commercial thermoplastic polyurethane (Duralast 4203 and 4758). EPDM-based compounds showed different filler-dependent behaviors, formulations filled with carbon black (E3) had the lowest wear rate (1.45 × 10?4 mm³ N?¹ m?¹) and increased load-bearing capacity, while samples modified with silica and plasticizer (E4, E5) had better conformability and damping but less hardness. Compounded EPDMs showed wider deformation zones because of their lower modulus and filler-matrix interfacial fluctuations, while commercial grades exhibited shallower wear scars (= 380 µm), according to optical profilometry. The Archard model-based lifetime estimation showed that, under 10 N and 30 mm/s, operational endurance ranged from 3.1 to 6.2 years. Because of its low wear rate and steady interfacial behavior, E3 had the longest anticipated life. For medium-load hydraulic sealing applications, these results demonstrate the possibility of customized EPDM formulations as affordable substitutes for commercial polyurethanes. They also offer a quantitative foundation for material selection and lifespan prediction.

Durability↗
DOE OSTI2026

Production of Renewable Solvents and Monomers from Lignocellulosic Feedstocks

Lignocellulosic biomass is pretreated and broken down into cellulosic sugars. The cellulosic sugars are converted to mevalonolactone (MVL) using Visolis’ proprietary microbes. The MVL containing broth is separated from the cells, deashed-decolorized, concentrated and fed into a catalytic reactor to develop anhydro mevalonolactone (aMVL), and 3-methyl pentanediol (3MPD). The products were separated by distillation into high purity compounds as solvent or polymer applications.

3-methyl pentanediol, polymer, solvent↗
DOE OSTI2020

Physical Bond Breaking in Associating Copolymer Liquids

We combine ideas from polymer and glassy liquid physics to construct a new model for the bond breaking time scale of attractive sticker groups in associating copolymer liquids that form transient networks. The activated event is argued to be a two-step process, involving first the release of the non-sticker dynamic caging constraints that defines the primary alpha relaxation, followed by attractive stickers surmounting an association free energy barrier subject to a local frictional resistance which can be strongly affected by relaxation-diffusion decoupling. Here, the ideas embedded in the model produce a consistent and good description of the bond breaking timescale for diverse polymer chemistries and architectures as a function of temperature and fraction of sticky groups. Chemically sensible values for association free energies are deduced. In strong contrast, the existing phenomenological models are shown to incur qualitative failures.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Effect of Branch Length on the Structural and Separation Properties of Hyperbranched Poly(1,3-dioxolane)

Polymers containing poly(ethylene oxide) (PEO) demonstrate superior membrane CO 2 /N 2 separation properties owing to their polar ether oxygen groups exhibiting strong affinity toward CO2. Poly(1,3-dioxolane) (PDXL) shows an ether oxygen content higher than PEO and is expected to have higher CO 2 /N 2 solubility selectivity. However, similar to PEO, the high crystallinity of PDXL greatly reduces its gas permeability. Herein, amorphous PDXL-based hyperbranched polymers were synthesized by ring opening of 1,3-dioxolane (DXL) to form poly(1,3-dioxolane) acrylate (DXLAn) followed by photopolymerization. The repeating unit of DXL (n) or branch length was systematically varied from 4 to 12 to yield amorphous polymers. The chemical and physical properties of the obtained polymers (PDXLAn) were thoroughly evaluated and used to interpret pure- and mixed-gas transport characteristics. The polymers exhibit attractive CO 2 /N 2 and CO 2 /CH 4 separation properties. For example, PDXLA8 exhibits a CO 2 permeability of 220 Barrer and CO 2 /N 2 selectivity of 56 at 35 °C, surpassing Robeson’s 2008 upper bound, and it shows robust separation performance when evaluated with simulated flue gas at 60 °C. This study demonstrates that hyperbranched structures are an effective route to construct amorphous yet highly polar polymers and that chain end groups are instrumental in determining the structural and gas transport characteristics.

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

Formation of uranium oxy-carbide and uranium carbide via conversion of polymer covered uranium dioxide by laser-based thermal processing

Conventional formation of carbonaceous uranium compounds requires bulk processing using furnace-based approaches. Here, a methodology employing polymer covered uranium dioxide and laser-based heating is explored to enable rapid, localized formation of carbonaceous uranium compounds. Specifically, heating of poly(methyl methacrylate) covered uranium dioxide powder to high temperatures using laser irradiation in argon and methane gaseous environments was investigated. Decomposition of material and reactions induced by laser irradiation were probed in situ by residual gas analysis using a benchtop mass spectrometer. In this study, to determine the effect on the resultant material phase, three different process parameters were varied: gaseous atmosphere, laser power, and laser irradiation time. Material processed under varying conditions was analyzed using powder X-ray diffraction and scanning electron microscopy. This work realized the conversion of uranium dioxide into uranium oxy-carbide(s) and uranium carbide(s) phases, at over 60 wt.%, via the polymer surface application and laser-based thermal decomposition methodology.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Polyvinyl acetate-based polymer host for optical and far-infrared spectroscopy of individualized nanoparticles

Preparation techniques for producing films of individualized solution-dispersed nanoparticles (NPs) for optical spectroscopy are frequently technically challenging and tailored for a specific NP system. In this work, we present a rapid, easy, and economical technique for producing polyvinyl acetate (PVAc)-based NP-polymer films on the order of 100’s of micrometers thick that exhibit high uniformity, low aggregation, excellent optical transparency, and low terahertz absorption. In addition, we find that these films are robust at cryogenic temperatures and have a high laser damage threshold of 0.3 TW cm –2 , which make them suitable for pulsed laser measurements. We show that free-standing, flexible, PVAc films can incorporate both one-dimensional single-wall carbon nanotubes (SWCNTs) and zero-dimensional Au NPs. Using absorbance, Raman scattering, and photoluminescence excitation spectroscopy, we observe that SWCNT individualization is maintained, and minimized polymer strain imposed, when the nanotubes are transitioned from the solution to the polymer host. This PVAc-based polymer host presents researchers with a straightforward method for producing free-standing and flexible NP films with low aggregation.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Hierarchical thermal-conductive polymer nanocomposites for thermal management

Managing heat in electrical conductors is a major challenge to meet the demands for sustainable energy use and electrical reliability, most notably power electronics and energy-critical electrical machines. Achieving such disparate functionalities, such as high temperature thermal and electrical reliability, require rational design and manufacturing of thermal conductor material and its hierarchical structures. Here we present hierarchical thermal-conductive nanocomposites, consisting of nanostructured ceramic conformal coating and aligned ultrahigh molecular weight polyethylene fiber, to tailor heat dissipation in electric conductors. The hybrid aligned thermal interface exhibits a highly desirable temperature dependent anisotropic high thermal conductivity with 0.98W m –1 K –1 and dielectric strength with 3.4. In addition, electrically insulating thermal interfaces demonstrate high-performing and reliable electrical systems under the dynamic load conditions. The surface temperature of heterogeneous ceramic-polymer encapsulated conductor is 17.8 °C lower than that of polymer-encapsulated conductor at the same electrical load. Consequently, the findings shown here hold great promises for directing heat extraction in electrical machine systems, advancing thermal management for emerging electronic applications.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Effects of tacticity and chiral center-to-dipole distance on mesogen-free liquid crystalline self-assembly of sulfonyl-containing comb-like polymers

In this report, new approaches were implemented to achieve novel ferroelectric liquid crystalline self-assembly in mesogen-free comb-like isotactic polyoxypropylenes (iPOPs) bearing mono- or di-sulfonyl groups, which have potential to exhibit high spontaneous polarization for applications in advanced electronic devices. iPOPs with n-alkylsulfonylpentylthioether side chains (iPOP-SC 5 SO 2 C n , where C n is the alkyl tail with n being either 12 or 8) were prepared via a post-polymerization substitution reaction from isotactic poly[(R)-(–)-epichlorohydrin]. Here, the effects of main-chain tacticity, chiral center-to-dipole distance, number of sulfonyl dipoles per side chain, and n-alkyl tail length on the liquid crystalline self-assembly behavior were investigated by comparing iPOPs with their atactic counterparts. First, when the sulfonyl dipole was placed far away from the chiral center in iPOP-SC 5 SO 2 C n compared with our previously reported isotactic polyethers with n-alkylsulfonyl side chains (iPOP-SO 2 C n ), the dipole–dipole interactions among the side chains decreased, which led to more liquid crystalline phases. Smectic E (SmE) and A (SmA) phases were observed after crystal melting; however, the main-chain chiral center was found to have an insignificant effect on the liquid crystalline assembly when compared to the atactic samples. Second, the longer C n tails increased the transition temperatures as a result of stronger van der Waals interactions. Third, after the thioether linkage in the side chain was oxidized into the sulfonyl group, the chiral center–dipole and dipole–dipole interactions in the resultant polymers (i.e., iPOP-SO 2 C 5 SO 2 C n ) enhanced. As a result, the liquid crystalline phase transitions (i.e., crystal → SmE → SmA → I) were pushed to higher temperatures. The knowledge gained in this study will help us further design and achieve the ferroelectric smectic C* phase in mesogen-free comb-like sulfonylated liquid crystalline polymers.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Renewable and Biodegradable Polyurethane Foams with Aliphatic Diisocyanates

The transition to renewable plastics will require the development of substitutes with existing industrial standards and manufacturing processes. Polyurethanes (PU), versatile plastics, are traditionally dominated by aromatic diisocyanates, which are challenging to derive from renewable sources. However, for higher biocontent, it is crucial to utilize aliphatic diisocyanates, which can be sourced from renewable plant or algae waste streams. Historically, PU foams relied on aromatic diisocyanates for essential hard segments, resulting in desired physical properties. Here, we report the generation of high-performance renewable and biodegradable PU foams utilizing aliphatic diisocyanates and aromatic polyols, translating hard segments into the polyester polyol component using biosourced furan dicarboxylic acid (FDCA) monomers. We demonstrate that an FDCA-based PU is suitable for foams with performance characteristics that meet commercial tolerances and can biodegrade under backyard compost conditions. Here, this demonstrates steps toward redesigning traditional petrochemical-based polymers to accommodate new biological monomers.

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

Bayesian estimations of orientation distribution functions from small-angle scattering enable direct prediction of mechanical stress in anisotropic materials

Properties of soft materials are influenced by their anisotropic structuring under nonequilibrium fields. Although anisotropic structure-property relationships have been extensively explored theoretically, comparison to experiments requires determination of the microstructural orientation probability distribution function (OPDF) of microstructural elements. Small angle scattering (SAS) measurements encode information about the OPDF, but tools to navigate this connection are incomplete. Here, we develop and validate an explicit framework to link arbitrary OPDFs to SAS measurements. Specifically, we propose, validate, and apply a method, maximum a posteriori scattering inference (MAPSI), whereby the OPDF may be obtained from SAS measurements using a Bayesian estimation method. Using this method, we obtain estimates of the full 3D OPDF for two model semidilute fd-virus (rodlike) dispersions at concentrations that are approximately equal to and twice the overlap concentration. From the OPDF, we calculate its second and fourth moments and compare these to predictions for a dilute suspension of rigid rods and to a recent theory for semidilute suspensions. Finally, we use both the theoretical and measured moments to calculate the stress, both for dilute and semidilute suspensions. These predictions are not only compared to each other, but also to measured values of the shear stress, and point to new insights into the behavior of suspensions of highly elongated particles in the transition between dilute and semidilute behavior. We also use this new framework to provide perspective on the connection between scalar parameterizations of scattering and the OPDF that have frequently been used in the past. Here, the new tools developed in this work provide an unprecedented path toward experimental validation of dynamical theories of rodlike colloids and polymers, and for measurement of nonequilibrium structures and stresses of other complex fluids and soft materials with SAS.

36 MATERIALS SCIENCE↗