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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Direct Evidence of Graphene-Induced Molecular Reorientation in Polymer Films

For the first time, direct evidence of graphene-induced molecular reorientation in polymer films using polarization modulated infrared reflection absorption spectroscopy (PMIRRAS) are presented. By creating favorable electrostatic interactions, graphene-polymer interfaces can be controlled by varying polymer and solvent composition. After trans of unmodified graphene from copper onto a polymer substrate, polymer chain rearrangement relative to the orientation at the polymer-copper interface is observed using PM-IRRAS. Transfer success is characterized using both optical transmission measurements and Raman spectroscopy to quantify the transfer fidelity, i.e. graphene coverage fraction. Taken together, oxygencontaining poly(ethylene-co-vinyl acetate) shows more polymer chain rearrangement and better graphene coverage compared to oxygen-free polyethylene. Polymer composition seems to dominate graphene-polymer interactions while solvent choice has a smaller effect on transfer quality. These results are the first direct measurement of this effect and point towards the possibility of engineering graphene-polymer interactions for specific applications.

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

Intermediate-phase engineering via dimethylammonium cation additive for stable perovskite solar cells

Achieving the long-term stability of perovskite solar cells is arguably the most important challenge required to enable widespread commercialization. Understanding the perovskite crystallization process and its direct impact on device stability is critical to achieving this goal. The commonly employed dimethyl-formamide/dimethyl-sulfoxide solvent preparation method results in a poor crystal quality and microstructure of the polycrystalline perovskite films. In this work, we introduce a high-temperature dimethyl-sulfoxide-free processing method that utilizes dimethylammonium chloride as an additive to control the perovskite intermediate precursor phases. By controlling the crystallization sequence, we tune the grain size, texturing, orientation (corner-up versus face-up) and crystallinity of the formamidinium (FA)/caesium (FA) y Cs 1-y Pb(I x Br 1-x )3 perovskite system. A population of encapsulated devices showed improved operational stability, with a median T80 lifetime (the time over which the device power conversion efficiency decreases to 80% of its initial value) for the steady-state power conversion efficiency of 1,190 hours, and a champion device showed a T80 of 1,410 hours, under simulated sunlight at 65 degrees C in air, under open-circuit conditions. In conclusion, this work highlights the importance of material quality in achieving the long-term operational stability of perovskite optoelectronic devices.

14 SOLAR ENERGY↗
DOE OSTI2020

Expeditious synthesis of covalent organic frameworks: a review

Covalent organic frameworks (COFs), a burgeoning class of crystalline porous materials constructed by covalently connecting organic building blocks, have garnered tremendous attention. The predominant solvothermal synthesis of COFs usually requires high temperature and long reaction times (three days or longer), which creates substantial obstacles for their accelerated discovery and exploration in practical applications. Hence, the expeditious synthesis of COFs without compromising their inherent properties is exceedingly appealing from the viewpoint of cost, time, and energy footprint. To overcome the sluggishness of the synthesis, considerable efforts have been invested in the rapid synthesis of high-quality COFs through innovations in energy source, catalyst, solvent, monomer, nucleation, and workup activation, leading to a drastic reduction of reaction time from multiple days to a few hours, and even to seconds in some cases. In this contribution, we provide a comprehensive overview of the advances in expediting the synthesis science of COFs. Though a nascent effort, six prevalent strategies have been identified for the rapid synthesis of COFs, which have led to intriguing applications in a diverse range of areas including gas adsorption, separation, heterogeneous catalysis, environmental remediation, and photodynamic therapy. We also outline the major challenges and perspectives on the future directions empowered by expeditious COF synthesis.

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

Fabrication of metal-organic framework thin films for luminescent sensing applications

Metal−organic frameworks (MOFs) have emerged as an exciting material class due to their nearly infinite design space: an inexhaustible combination of metal centers, organic linkers, and reaction conditions may be leveraged to obtained desired optical, physical, and chemical properties. This rich synthetic diversity enables properties such as pore dimensions and functionality to be rationally tailored for highly selective and sensitive detection of target analytes. Luminescent MOF-based sensors in particular offer advantages including low cost, portability, and ease-of-use. Often, performance is maximized by utilizing the luminescent MOF in thin film form, for example by integrating the film onto an optical fiber, yet the synthesis of high-quality MOF thin films often requires tedious, expensive, and/or slow approaches. Here, we demonstrate a rapid, simple strategy for growing copper MOFs using metal oxide templates; the concept is first demonstrated with a well-studied system, copper-1,3,5-benznetricarboxylate (Cu-BTC). Variables such as the choice of solvent, pH, and the choice of the copper salt anion all govern thin film quality. We then extend this method to synthesize a solvent and metal-responsive copper MOF that is particularly effective at detecting aluminum, an economically critical metal, at trace concentrations using a fully portable luminescence spectrometer. Taken together, this work demonstrates a convenient, versatile, and sustainable method for developing high quality MOF thin film-based optical sensors.

Crawford, Scott↗
DOE OSTI2023

A high-solid DES pretreatment using never-dried biomass as the starting material: towards high-quality lignin fractionation

This study investigated a high-solid diol deep eutectic solvent (DES) pretreatment using a wet substrate as the starting material. This pretreatment led to a remarkable glucan saccharification of 94.8% with efficient lignin and xylan removal (as high as 63.1% and 73.0%, respectively). Here the chemical structures of the substrates were analyzed comprehensively to reveal the impact of the pretreatment. In addition, over 90% of the removed lignin was recovered from the pretreated liquid, which exhibited a well-preserved β-O-4 structure (46–56/100Ar). The protection mechanism of our DES was investigated by 2D HSQC NMR, GPC, and 31 P NMR analysis. This study emphasized that diol-based DES pretreatment of undried lignocellulosic biomass at a high-solid loading can significantly utilize both carbohydrates and lignin fractions with high saccharification yields and high-quality lignin as a co-product.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Assessment and Non-Destructive Evaluation of the Influence of Residual Solvent on a Two-Part Epoxy-Based Adhesive Using Ultrasonics

Polymers are increasingly being used in higher demanding applications due to their ability to tailor the properties of structures while allowing for a weight and cost reduction. Solvents play an important role in the manufacture of polymeric structures since they allow for a reduction in the polymer’s viscosity or assist with the dispersion of fillers into the polymer matrix. However, the incorrect removal of the solvent affects both the physical and chemical properties of polymeric materials. The presence of residual solvent can also negatively affect the curing kinetics and the final quality of polymers. Destructive testing is mainly performed to characterize the properties of these materials. However, this type of testing involves using lab-type equipment that cannot be taken in-field to perform in situ testing and requires a specific sample preparation. Here, a method is presented to non-destructively evaluate the curing process and final viscoelastic properties of polymeric materials using ultrasonics. In this study, changes in longitudinal sound speed were detected during the curing of an aerospace epoxy adhesive as a result of variations in polymer chemistry. To simulate the presence of residual solvent, samples containing different weight percentages of isopropyl alcohol were manufactured and tested using ultrasonics. Thermogravimetric analysis was used to show changes in the decomposition of the adhesive due to the presence of IPA within the polymer structure. Adding 2, 4, and 6 wt.% of IPA decreased the adhesive’s lap shear strength by 40, 58, and 71%, respectively. Ultrasonics were used to show how the solvent influenced the curing process and the final sound speed of the adhesive. Young’s modulus and Poisson’s ratio were determined using both the longitudinal and shear sound speeds of the adhesive. Using ultrasonics has the potential to non-invasively characterize the quality of polymers in both an in-field and manufacturing settings, ensuring their reliability during use in demanding applications.

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

Cast Film Production with Polyethylene Recycled from a Post-Industrial Printed Multilayer Film by Solvent-Targeted Recovery and Precipitation

The solvent-targeted recovery and precipitation (STRAP) process separates and recovers the constituent resins in multilayer plastic packaging films by selective polymer dissolution. In this work, three different experimental methods were considered to recover a polyethylene (PE) resin from a printed multilayer film by STRAP. The methods consisted of (1) a filter bag system, (2) a Soxhlet extraction, and (3) a jacketed dissolution vessel. Cast films were produced with the PE recovered from each method and were analyzed for color, mechanical properties, and number of impurities. High-quality recycled PE cast films can be produced by increasing the solvent to plastic ratio, including a filter pore size of 100 μm, and optimizing temperature control in STRAP. Furthermore, this study demonstrates that STRAP polymers can be recycled back into plastic films, enabling the potential circularity of these packaging materials.

36 MATERIALS SCIENCE↗
DOE OSTI2022

A universal co-solvent dilution strategy enables facile and cost-effective fabrication of perovskite photovoltaics

Cost management and toxic waste generation are two key issues that must be addressed before the commercialization of perovskite optoelectronic devices. We report a groundbreaking strategy for eco-friendly and cost-effective fabrication of highly efficient perovskite solar cells. This strategy involves the usage of a high volatility co-solvent, which dilutes perovskite precursors to a lower concentration (<0.5 M) while retaining similar film quality and device performance as a high concentration (>1.4 M) solution. More than 70% of toxic waste and material cost can be reduced. Mechanistic insights reveal ultra-rapid evaporation of the co-solvent together with beneficial alteration of the precursor colloidal chemistry upon dilution with co-solvent, which in-situ studies and theoretical simulations confirm. The co-solvent tuned precursor colloidal properties also contribute to the enhancement of the stability of precursor solution, which extends its processing window thus minimizing the waste. This strategy is universally successful across different perovskite compositions, and scales from small devices to large-scale modules using industrial spin-coating, potentially easing the lab-to-fab translation of perovskite technologies.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Cold air quench control of local crystallization environment in fully air-processed carbon-based perovskite solar cells

Carbon-based perovskite solar cells (C-PSCs) present a low-cost route to efficient photovoltaic technology. Gas quenching is an essential process commonly used for solvent extraction in scalable module fabrication using solution processes, but film quality remains highly sensitive to the localized environmental processing temperature, especially during intermediate phase transitions before perovskite film high temperature annealing. In this study, we introduce a cold air quench strategy to precisely control the local crystallization temperature that simultaneously promotes uniform crystallization and facilitates strain relaxation in fully air-processed C-PSCs. It is found that implementing dry air at 10 °C as the quenching gas yields a champion power conversion efficiency (PCE) of 20.52 %, with preferential (110) orientation and reduced, homogenized in-plane strain. This newly developed technique of a cost-effective low temperature air quenching process also enhances carrier lifetime, reduces interface recombination, and improves charge extraction. Furthermore, this work presents cold air quenching as a scalable, economic method to control perovskite crystallization and strain in C-PSC fabrication, advancing the industrial viability of high-performance perovskite modules.

14 SOLAR ENERGY↗
DOE OSTI2020

Response Surface Methodology As a New Approach for Finding Optimal MALDI Matrix Spraying Parameters for Mass Spectrometry Imaging

Automated spraying devices have become ubiquitous in laboratories employing matrixassisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), in part because they permit control of a number of matrix application parameters that can easily be reproduced for intra- and interlaboratory studies. Determining the optimal parameters for MALDI matrix application, such as temperature, flow rate, spraying velocity, number of spraying cycles, and solvent composition for matrix application, is critical for obtaining high-quality MALDI-MSI data. However, there are no established approaches for optimizing these multiple parameters simultaneously. Instead optimization is performed iteratively (i.e., one parameter at a time), which is time consuming and can lead to overall non-optimal settings. In this report, we demonstrate the use a novel experimental design and the response surface methodology to optimize five parameters of MALDI matrix application using a robotic sprayer. Thirtytwo combinations of MALDI matrix spraying conditions were tested, which allowed us to elucidate relationships between each of the application parameters as determined by MALDI-MS (specifically, using a 15 Tesla Fourier transform ion cyclotron resonance mass spectrometer). As such, we were able to determine the optimal automated spraying parameters that minimized signal de-localization and enabled high MALDI sensitivity. We envision this optimization strategy can be utilized for other MALDI-MSI applications, tissue types, and matrix application approaches.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Detection of Anatoxins in Human Urine by Liquid Chromatography Triple Quadrupole Mass Spectrometry and ELISA

Harmful cyanobacterial blooms are becoming more common and persistent around the world. When in bloom, various cyanobacterial strains can produce anatoxins in high concentrations, which, unlike other cyanobacterial toxins, may be present in clear water. Potential human and animal exposures to anatoxins occur mainly through unintentional ingestion of contaminated algal mats and water. To address this public health threat, we developed and validated an LC-MS/MS method to detect anatoxins in human urine to confirm exposures. Pooled urine was fortified with anatoxin-a and dihydroanatoxin at concentrations from 10.0 to 500 ng/mL to create calibrators and quality control samples. Samples were diluted with isotopically labeled anatoxin and solvent prior to LC-MS/MS analysis. This method can accurately quantitate anatoxin-a with inter- and intraday accuracies ranging from 98.5 to 103% and relative standard deviations < 15%, which is within analytical guidelines for mass spectrometry methods. Additionally, this method qualitatively detects a common degradation product of anatoxin, dihydroanatoxin, above 10 ng/mL. We also evaluated a commercial anatoxin-a ELISA kit for potential diagnostic use; however, numerous false positives were detected from unexposed individual human urine samples. In conclusion, we have developed a method to detect anatoxins precisely and accurately in urine samples, addressing a public health area of concern, which can be applied to future exposure events.

urine↗
DOE OSTI2026

Delamination of Multilayer Plastic Films to Recover Polyethylene with Favorable Mechanical Properties

Multilayer plastic films play a critical role in packaging, with each polymer layer contributing specific properties to the multilayer film. Multilayer plastic films are not currently recyclable due to the bound polymers. With multilayer film production of about 20 million metric tons in 2024 and rising, endof- life treatment becomes pressing. This work presents a scalable solvent-based delamination recycling process that is applied to commercial postindustrial multimaterial films to unbind the materials within a multilayer film by dissolving only the adhesive layer and recover polyethylene (PE) as an intact solid film. Solventbased delamination is a simple process that allows the complete recovery of materials and solvents used in the process. The delaminating solvent, 88% formic acid in water, induces delamination of PE/PEI/PET and PE/PU/PET films at 70 °C in under an hour. Recovered PE has no contamination detected by Fourier transform infrared spectroscopy and mechanical properties on par with those of virgin resin. The recovery of high-quality solid PE film fit for reprocessing, at low operating temperatures and with closed-loop solvent reuse, promotes delamination as a low energy consumption and environmentally friendly recycling process. PE recovered from delamination can be reused in equivalent products, promoting circularity of multimaterial films.

chemical recycling↗
DOE OSTI2024

Chemical recycling of mixed textile waste

Globally, less than 0.5% of postconsumer textile waste is recycled, with the majority incinerated or ending up in landfills. Most postconsumer textiles are mixed fibers, complicating mechanical recycling due to material blends and contaminants. Here, we demonstrate the chemical conversion of postconsumer mixed textile waste using microwave-assisted glycolysis over a ZnO catalyst followed by solvent dissolution. This approach electrifies the process heat while allowing rapid depolymerization of polyester and spandex to their monomers in 15 minutes. A simple solvent dissolution enables the separation of cotton and nylon. We assess the quality of all components through extensive material characterization, discuss their potential for sustainable recycling, and provide a techno-economic analysis of the economic feasibility of the process.

Science & Technology - Other Topics↗
DOE OSTI2021

Method to synthesize nanoparticle supercrystals

Highly ordered arrays of 3D faceted nanoparticle supercrystals are formed by self-assembly with controlled nanoparticle packing and unique facet dependent optical property by using a binary solvent diffusion method. The binary diffusion results in supercrystals whose size and quality are determined by initial nanoparticle concentration and diffusion speed. The supercrystal solids display unique facet-dependent surface plasmonic and surface-enhanced Raman characteristics. The supercrystals have potential applications in areas such as optics, electronics, and sensor platforms.

Fan, Hongyou↗
DOE OSTI2021

Solvent-Free Coating of Organic Semiconductor Membranes with Centimetric Crystalline Domains

Organic semiconductors (OSCs) have shown great promise in a variety of applications. Although solution processing of OSCs has resulted in high-quality films, exquisite control of structural development to minimize defect formation during large-scale fabrication remains formidable. Compounding this challenge is the use of halogenated organic solvents, which poses significant health and environmental hazards. However, the solvent-free techniques introduced thus far impose additional limitations on solidification kinetics; the resulting OSC thin films are often more defective than those processed from solution. Here, a solvent-free technique is reported to prepare OSC membranes with centimetric crystalline domains. Leveraging the tendency for liquid crystalline materials to preferentially orient, OSCs are “prealigned” by depositing them from the melt over a metal frame to form a freely suspended membrane. Additionally, crystallization from this prealigned phase affords membranes with unprecedented structural order across macroscopic distances. Field-effect transistors comprising membranes of dioctyl[1]-benzothieno[3,2-b][1]benzothiophene (C8BTBT) and didodecyl[1]-benzothieno[3,2-b][1]benzothiophene (C12BTBT) having centimeter-sized domains as active layers exhibit a hole mobility of ≈8.6 cm2 V -1 s -1 , superseding the mobility of any transistors whose active layers are deposited from melt. This technique is scalable to yield membranes with large crystalline domains over wafer dimensions, making it amenable for broad applications in large-area organic electronics.

36 MATERIALS SCIENCE↗
DOE OSTI2026

In-Situ Ligand-Induced Chirality Transfer in Emissive CdSe Nanoplatelets

Terminating semiconductor nanocrystals with chiral organic ligands can induce chiroptical properties that combine the chiral character of the ligands with the strong and tunable optical properties of the nanocrystal. However, the synthesis of such chiral-modified nanocrystals is currently limited by solvent incompatibility between polar chiral ligands and nonpolar traditional ligands, as well as by ligand dissolution behavior that ultimately compromises nanocrystal quality and the degree to which chiroptical properties can be manipulated. In this work, we demonstrate a single-step synthesis of chiral cadmium selenide (CdSe) nanoplatelets (NPLs) that eliminates the need for postsynthetic ligand exchange in aqueous solvents, resulting in highly emissive chiral CdSe NPLs. By directly incorporating chiral aminodecanoic acid ligands during synthesis, we achieve in situ ligand binding and chirality transfer to CdSe NPLs. This approach produces CdSe NPLs with high photoluminescence quantum efficiencies of 50% and circular dichroism dissymmetry factors (gCD) on the order of 10 –4 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Wet Brush Homopolymers as “Smart Solvents” for Rapid, Large Period Block Copolymer Thin Film Self-Assembly

The spontaneous formation of periodic nanopatterns through the self-assembly of block copolymer (BCP) thin films offers an enticing path to engineer functional material properties over large areas, but the prohibitively slow ordering of ultrahigh molecular weight BCPs that generate large pattern periods (>100 nm) severely restricts the design space in which BCPs may be used. Here, we demonstrate that blending lamellae-forming polystyrene-block-poly(methyl methacrylate) diblock copolymers with very low molecular weight polystyrene and poly(methyl methacrylate) homopolymers can reduce by an order-of-magnitude the times required to form ordered large period patterns through solvent vapor annealing. Using in situ grazing-incidence small-angle X-ray scattering and ex situ electron microscopy, we show that the added homopolymer plasticizers act as a “smart solvent”: They increase the mobility of the long BCP chains by amplifying the dilution effect during solvent vapor annealing but segregate to like domains during subsequent thermal annealing to produce high-quality patterns with periods that may exceed 200 nm, which are readily transferred to other materials. The dramatic impact of homopolymer plasticizers may help extend the use of BCPs into new areas, particularly for visible light photonic applications that demand larger period nanopatterns.

36 MATERIALS SCIENCE↗
DOE OSTI2026

A Guide to Nonaqueous Electrochemistry of f-Element Complexes

Electrochemistry is a powerful tool for assessing and understanding the redox chemistry of molecular complexes. Cyclic voltammetry enables the f-element community to study molecules in unusually high or low oxidation states, which potentially pose important broad-scope questions of electronic structure. In the pursuit of boundary-pushing compounds, reactive air- and moisture-sensitive species are often encountered, which can be challenging to characterize, especially when they are chemically incompatible with certain solvents, electrolytes, or electrodes or when their potentials lie outside of common electrochemical windows. Nonaqueous solvents and pseudo reference electrodes complicate many of the standard practices in acquiring high-quality and reproducible electrochemical data. This guide presents a detailed discussion of selecting appropriate cell conditions and referencing and addresses metrics for evaluating electrochemical and chemical reversibility. These methodological approaches have been extended to best practices for the electrochemical analysis of radioactive transuranic complexes.

Electrodes↗