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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

A Bis(arenesulfonyl) Peroxide, an Ambient-Stable Oxidant, Is a Strong p-Dopant for Organic Semiconductors

Strong p-dopants are required to dope high-ionization energy organic semiconductors for a variety of potential applications, but strong, simple one-electron oxidants are typically sensitive to reduction by atmospheric moisture and thus challenging to store or handle. Here we show that bis(3,5-bis(trifluoromethyl)benzenesulfonyl) peroxide─a dimer formed by two highly oxidizing radicals─can function as a water-stable yet powerful oxidant, cleanly reacting with some organic semiconductors to form two radical cations and two 3,5-bis-(trifluoromethyl)benzenesulfonate anions, although in other cases sulfonylation reactions can also occur. Notably, this peroxide is capable of p-doping the high-ionization energy polymer poly[(9,9-dioctylfluorene-2,7-diyl)- alt -(benzo[2,1,3]thiadiazol-4,7-diyl)] (F8BT) to afford electrical conductivities of up to 0.03 S cm –1 , while its use with electron-rich poly(3,4-dialkoxythiophene-2,5-diyl) derivatives can afford values up to 100 S cm –1 . Quantum-chemical calculations reveal the peroxide oxidant behaves in a fashion mirroring that of relatively oxygen-stable, but highly reducing, n-dopants that have been developed based on dimers of organic radicals or organometallic sandwich compounds.

doping↗
DOE OSTI2023

Non‐OH‐driven liquid‐phase chemistry in water microdroplets

Abstract Water microdroplets containing organic and fluorinated compounds, such as formate, perfluorooctanoic acid (PFOA) and triflic acid, were exposed to a radiofrequency glow discharge plasma with a droplet residence time on the order of milliseconds. Triflic acid remained unaffected by any plasma condition while >75% decomposition of formate and PFOA could be achieved. In situ hydroxyl (OH)‐laser‐induced fluorescence measurements near the droplets confirmed that the conversion was independent of the OH flux to the droplet. A series of control experiments suggest that the contribution of vacuum UV photons in such decomposition of aqueous compounds can be significant for He and He + 17% Ar plasmas and can also explain unexpected decomposition trends as a function of droplet residence time in the plasma.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

PolyDODT: a macrocyclic elastomer with unusual properties

The effect of reaction conditions on the structure of poly(3,6-dioxa-1,8-octanedithiol) (polyDODT) made by Reversible Radical Recombination Polymerization (R3P) using triethylamine (TEA), H 2 O 2 and air was investigated. 800 MHz (1 and 2D) NMR was used to investigate the polymer structures. Sensitivity analysis provided direct evidence for high purity cyclic polyDODT up to M n ~ 100 000 g mol –1 . Here, comparative analysis by High Resolution Multidetector Size Exclusion Chromatography (SEC) using integrated data showed that the cycles had lower viscosity and were more compact (both for R g and R h ) than linear samples of similar molecular weight. However, differential data revealed unusual behavior. While lower molecular weight cyclic polymers eluted later and had lower intrinsic viscosity than their linear counterparts at the same molecular weight, at higher molecular weights the polymers showed strange behavior: both the diffusion coefficient measured by Quasielastic Light Scattering (QELS) and Mark–Houwink–Sakurada plots of intrinsic viscosity for linear and cyclic polyDODT were found to converge. R3P, an aqueous based “green” method is capable of producing polymers at the 10–100 g scale in the lab, which will allow more detailed studies of this new class of biodegradable elastomers so further experimentation can be performed to elucidate the reasons for the unusual findings.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Organocatalysis in ring opening copolymerization as a means of tailoring molecular weight dispersity and the subsequent impact on physical properties in 4D printable photopolymers

Vat photopolymerization 3D printing has traditionally relied on free radical crosslinking between alkenes to produce non-degradable parts, which may have limited use in the biomedical and clinical spaces. Photopolymer resins containing functionalized degradable polymers, specifically polyesters, are greatly interesting for 3D printing tissue scaffolds and medical devices. Unfortunately, most polyesters produced for these applications have been made using metal-containing catalysts, which are not without risk for medical applications. Organocatalysis is a viable alternative route to achieving the same types of polyesters. Here, ring opening copolymerization (ROCOP) of allyl and cyclohexene-containing polyesters is examined using bipyridine and a guanidine-containing catalyst. The role of the catalysts, initiators, and cocatalysts are examined for bulk, open air ROCOP reactions. Unlike previous efforts with organocatalysis, the examined catalysts here could be used to tailor the dispersity of the polyesters, with ~10 kDa polyesters with dispersity ranging from 1.3 to 2.5 examined for the impact on rheological and thermomechanical properties related to resin/part behavior. The bipyridine catalysts and a thiourea cocatalyst further are shown, through the introduction of new fluorescence emissions of the purified polyesters. As a result, this work demonstrates that tuning the dispersity of polyester photopolymers provides a direct method of tailoring physical and optical properties in 3D/4D printable materials.

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

Improved analysis of arabinoxylan-bound hydroxycinnamate conjugates in grass cell walls

Background: Arabinoxylan in grass cell walls is acylated to varying extents by ferulate and p-coumarate at the 5-hydroxy position of arabinosyl residues branching off the xylan backbone. Some of these hydroxycinnamate units may then become involved in cell wall radical coupling reactions, resulting in ether and other linkages amongst themselves or to monolignols or oligolignols, thereby crosslinking arabinoxylan chains with each other and/or with lignin polymers. This crosslinking is assumed to increase the strength of the cell wall, and impedes the utilization of grass biomass in natural and industrial processes. A method for quantifying the degree of acylation in various grass tissues is, therefore, essential. We sought to reduce the incidence of hydroxycinnamate ester hydrolysis in our recently introduced method by utilizing more anhydrous conditions. Results: The improved methanolysis method minimizes the undesirable ester-cleavage of arabinose from ferulate and p-coumarate esters, and from diferulate dehydrodimers, and produces more methanolysis vs. hydrolysis of xylan-arabinosides, improving the yields of the desired feruloylated and p-coumaroylated methyl arabinosides and their diferulate analogs. Free ferulate and p-coumarate produced by ester-cleavage were reduced by 78% and 68%, respectively, and 21% and 39% more feruloyl and p-coumaroyl methyl arabinosides were detected in the more anhydrous method. The new protocol resulted in an estimated 56% less combined diferulate isomers in which only one acylated arabinosyl unit remained, and 170% more combined diferulate isomers conjugated to two arabinosyl units. Conclusions: Overall, the new protocol for mild acidolysis of grass cell walls is both recovering more ferulate- and p-coumarate-arabinose conjugates from the arabinoxylan and cleaving less of them down to free ferulic acid, p-coumaric acid, and dehydrodiferulates with just one arabinosyl ester. This cleaner method, especially when coupled with the orthogonal method for measuring monolignol hydroxycinnamate conjugates that have been incorporated into lignin, provides an enhanced tool to measure the extent of crosslinking in grass arabinoxylan chains, assisting in identification of useful grasses for biomass applications.

09 BIOMASS FUELS↗
DOE OSTI2024

Current status and outlook for ATRP

Atom transfer radical polymerization (ATRP) is one of the most often used controlled radical polymerization techniques. It employs very small amounts (ppm) of Cu complexes in the presence of various chemical reducing agents but also external stimuli such as light, electrical current or mechanical forces. It can be carried out in bulk, in solution, and in dispersed media. ATRP has been successfully used to prepare various polymers with controlled architecture and well-defined topology, composition, and functionality, as well as bioconjugates and organic–inorganic hybrids. This article summarizes the current status and also an outlook for ATRP.

ATRP↗
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 OSTI2022

Ultrasound controlled mechanophore activation in hydrogels for cancer therapy

Significance Biomedical application of mechanophores is the next frontier in polymer mechanochemistry. We report the concept, mechanochemical dynamic therapy (MDT), that utilizes remote, ultrasound-triggered mechanophore activation to enable anticancer activities. We selected an azo-based mechanophore to generate reactive free radicals (FRs) under the control of high-intensity focused ultrasound (HIFU), which subsequently produced ROS. We investigated two sets of in vitro mouse cancer models: 1) melanoma (B16F10) and 2) breast cancer (E0771). Inhibition of growth and decreases in viabilities of both B16F10 and E0771 were observed in correlation to the release of ROS by mechanophore activation. By circumventing the known issues in photodynamic therapy and sonodynamic therapy, we anticipate MDT to be a powerful anticancer tool complementary to other existing cancer treatments.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Density functional theory study on the coupling and reactions of diferuloylputrescine as a lignin monomer

Diferuloylputrescine has been found in a variety of plant species, and recent work has provided evidence of its covalent bonding into lignin. Results from nuclear magnetic resonance spectroscopy revealed the presence of bonding patterns consistent with homo-coupling of diferuloylputrescine and the possibility of cross-coupling with lignin. In the present work, density functional theory calculations have been applied to assess the energetics associated with radical coupling, rearomatization, and dehydrogenation for possible homo-coupled dimers of diferuloylputrescine and cross-coupled dimers of diferuloylputrescine and coniferyl alcohol. Furthermore, the values obtained for these reaction energetics are consistent with those reported for monolignols and other novel lignin monomers. As such, this study shows that there would be no thermodynamic impediment to the incorporation of diferuloylputrescine into the lignin polymer and its addition to the growing list of non-canonical lignin monomers.

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

Interdigitated conducting tetrathiafulvalene-based coordination networks

Here, assembly of a novel ethylenedithio-tetrathiafulvalene (EDT-TTF) derivative bearing two adjacent 4-thiopyridyl groups with M(NCS)2 nodes (M = Fe, Co) leads to two isostructural 1D coordination polymers showing an enhancement of their electronic conductivity by six orders of magnitude (10 –6 vs. 10 –12 S cm –1 ), upon surface oxidation by iodine and subsequent generation of EDT-TTF-based radicals.

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

LDRD Macromolcule Radiolysis Poster

Moving toward a circular carbon economy depends on enabling reuse of carbon-based macromolecules and increased recycling of waste products into higher value products. Macromolecules are challenging to valorize into products easily converted into liquid fuel or chemical feedstocks, due to their large and sometimes heterogeneous network of polymeric bonds. The novel aspect of this project is to show a proof of principle that radiolysis of macromolecules using “waste” radiation from energy production in the presence of radical capping donors presents an attractive opportunity to break down complex macromolecules into smaller molecules while controlling re-polymerization. This approach offers a new, cost-efficient way to utilize “waste” radiation and heat byproducts of nuclear energy production to convert a simple mixture of complex molecules into a complex mixture of small molecules, to be utilized as an energy source by the fuel industry, or to create value-added feedstocks for new polymers or commodity chemicals. Ionizing radiation can be harnessed to convert energy to molecules, adding value to low-value macromolecules as they are broken down into smaller, more easily separated feedstocks or fuels to be converted to a value-added product. This project will test 2 hypotheses. Hypothesis 1: Macromolecular materials that comprise biomass and coal or other macromolecules can be infused with radical capping donors (RCDs), and gamma irradiation of the resulting mixtures will produce ensembles of lower-molecular weight chemicals that can be more easily separated. If this expectation is realized, the conversion chemistry can be optimized by adjusting the feedstock composition, irradiation time, and choice of RCD.

02 - PETROLEUM↗
DOE OSTI2026

Growth in heterogeneous, evolving macromolecular networks: toward functional, biomimetic material

This report summarizes research carried out by the Balazs and Matyjaszewski Labs at Pitt and CMU, respectively, during 2025-26, supported by the DOE grant. It has produced the following 3 research articles and 2 review publications that acknowledged grant ER45998: 1. Computational Modeling of Hyperbranched Polymers 2. Synthesis of Structurally Tailored Networks 3. Sustainable and Oxygen-Tolerant Catalysis 4. A review paper on Current Status and Outlook for ATRP 5. A review paper on Future Directions for Atom Transfer Radical Polymerization

Balazs, Anna (ORCID:0000000255552692)↗
DOE OSTI2021

Assemblies of Polyacrylonitrile-Derived Photoactive Polymers as Blue and Green Light Photo-Cocatalysts for Cu-Catalyzed ATRP in Water and Organic Solvents

Photoluminescent nanosized quasi-spherical polymeric assemblies prepared by the hydrothermal reaction of polyacrylonitrile (PAN), ht-PLP PAN , were demonstrated to have the ability to photo-induce atom transfer radical polymerization (ATRP) catalyzed by low, parts per million concentrations of Cu II complex with tris(2-pyridylmethyl)amine (TPMA). Such photo induced ATRP reactions of acrylate and methacrylate monomers were performed in water or organic solvents, using ht-PLP PAN as the photo-cocatalyst under blue or green light irradiation. Mechanistic studies indicate that ht-PLP PAN helps to sustain the polymerization by facilitating the activation of alkyl bromide species by two modes: 1) green or blue light-driven photoreduction of the Cu II catalyst to the activating Cu I form, and 2) direct activation of dormant alkyl bromide species which occurs only under blue light. The photoreduction of the Cu II complex by ht-PLP PAN was confirmed by linear sweep voltammetry performed under illumination. Analysis of the polymerization kinetics in aqueous media indicated even though Cu I complexes comprised only 1–1.4% of all Cu species at equilibrium, they exhibited high activation rate constant and activated the alkyl bromide initiators five to six orders of magnitude faster than ht-PLP PAN .

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

Radical Coupling Reactions of Hydroxystilbene Glucosides and Coniferyl Alcohol: A Density Functional Theory Study

The monolignols, p-coumaryl, coniferyl, and sinapyl alcohol, arise from the general phenylpropanoid biosynthetic pathway. Increasingly, however, authentic lignin monomers derived from outside this process are being identified and found to be fully incorporated into the lignin polymer. Among them, hydroxystilbene glucosides, which are produced through a hybrid process that combines the phenylpropanoid and acetate/malonate pathways, have been experimentally detected in the bark lignin of Norway spruce (Picea abies). Several interunit linkages have been identified and proposed to occur through homo-coupling of the hydroxystilbene glucosides and their cross-coupling with coniferyl alcohol. In the current work, the thermodynamics of these coupling modes and subsequent rearomatization reactions have been evaluated by the application of density functional theory (DFT) calculations. The objective of this paper is to determine favorable coupling and cross-coupling modes to help explain the experimental observations and attempt to predict other favorable pathways that might be further elucidated via in vitro polymerization aided by synthetic models and detailed structural studies.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2026

A Versatile Method for Creating Ultrathin Films of Polyzwitterions with Antifouling Properties

Protein repellent (i.e., antifouling) properties of ultrathin polymeric films have been ascribed to the formation of a dense layer of adsorbed polymers, which causes steric hindrance to protein adsorption on underlying substrates. The antifouling properties of the films are hypothesized to be independent of polymer hydrophilicity based on previous studies involving uncharged polymers. Here, to test the hypothesis and extend it to the realm of charged polymers, we have developed a grafting method for creating ultrathin layers of polyzwitterions on solid surfaces. To demonstrate the efficacy of this method, poly[1-(3-sulfopropyl-1)-2-vinylpyridinium betaine] (P2VPPS) was synthesized via free-radical polymerization and immobilized onto surfaces by using a photoreactive benzophenone derivative as the cross-linker, which was covalently bonded to either quartz or Si/SiOx substrates through a silane anchor. We found that ultrathin films with thicknesses of less than 10 nm can be obtained in dry states using 365 nm ultraviolet (UV) cured/cross-linked surface coatings. These films were found to be hydrophilic and undergo structural rearrangements in the presence of water. The antifouling performance of the films was evaluated using Pseudomonas aeruginosa strain PAO1 bacterium as the fouling agent and exhibited antifouling properties with a kinetic control via the coating method (i.e., spin-coating and drop-casting). In particular, the surface area coverages due to the PAO1 cell attachment on the quartz substrates coated with P2VPPS were found to be ∼5% and ∼0% for the spin-coated and drop-casted films, respectively, after 4 h. These results show that the grafting method can be used to generate surfaces with antifouling properties based on ultrathin films of polyzwitterions.

Pseudomonas aeruginosa↗
DOE OSTI2021

A New Approach to Fundamental Mechanism Discovery in Polymer Upcycling

We present a new experimental methodology for detailed experimental investigations of depolymerization reactions over solid catalysts. This project aims to address a critical need in fundamental research on chemical upcycling of polymers – the lack of rapid, sensitive, isomerselective probing techniques for the detection of reaction intermediates and products. Our method combines a heterogeneous catalysis reactor for the study of multiphase (gas/polymer melt/solid) systems, coupled to a vacuum UV photoionization time-of-flight mass spectrometer. This apparatus draws on our expertise in probing complex gas-phase chemistry and enables highthroughput, detailed chemical speciation measurements of the gas phase above the catalyst, providing valuable information on the heterogeneous catalytic reactions. Using this approach, we investigated the depolymerization of high-density polyethylene (HDPE) over Ir-doped zeolite catalysts. We showed that the product distribution was dominated by low-molecular weight alkenes with terminal C=C double bonds and revealed the presence of many methyl-substituted alkenes and alkanes, suggesting extensive methyl radical chemistry. In addition, we investigated the fundamental reactivity of model oligomer molecules n-butane and isobutane over ZSM-5 zeolites. We demonstrated the first direct detection of methyl radical intermediates, confirming the key role of methyl in zeolite-catalyzed activation of alkanes. Our results show the potential of this experimental method to achieve deep insight into the complex depolymerization reactions and pave the way for detailed mechanistic studies, leading to increased fundamental understanding of key processes in chemical upcycling of polymers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗