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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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Mechanistic elucidation of the molecular weight dependence of corrosion inhibition afforded by polyetherimide coatings
Not provided.
Recovery of low molecular weight compounds from alkaline pretreatment liquor via membrane separations
Lignin is an abundant renewable resource that is a promising substrate for upgrading to fuels and chemicals.
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.
Mild aqueous metal catalyzed oxidative conversion of low-density polyethylene to low molecular weight aliphatic carboxylic acids
Aqueous oxidative deconstruction of low-density polyethylene (LDPE) using homogeneous first-row transition metal catalysts under mild conditions (130–150 °C and 100 PSI oxygen pressure).
Polymer dynamics at low molecular weight of poly(butylene oxide) star polymers
Star polymers are an interesting class of polymers to study based on their shape and dynamics. We use complementary techniques to study the polymer dynamics of star polymers with shorter side chains and compare them with linear counterparts.
Microfluidic-supported emulsion polymerization: molecular weight and concentration of surface-capping agents impact the formation of anisotropic polyvinylmethacrylate particles
Surface-capping agents—for example, amphiphilic surfactant molecules, water-soluble polymers, or polyelectrolytes—play a critical role during polymerization reactions for both the formation and stability of colloidal polymer particles.
Efficient Production of Low Molecular Weight carboxylic Acids via Mild Aqueous Catalytic Oxidation of Low-Density Polyethylene
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Retrofit & Expansion Project at Ultra-High Molecular Weight Polyethylene Plant: Completing a Full Domestic Supply Chain for Lithium-Ion Batteries (Final Scientific and Technical Report)
The UTEC-1 LIBS Retrofit and Expansion Project aimed to retrofit and expand Braskem’s UHMWPE unit in La Porte, TX to produce lithium-ion battery separator (LIBS) grade material and increase capacity. The project sought to strengthen the domestic supply chain for advanced battery manufacturing and reduce reliance on imports. While significant progress was achieved in conceptual design and FEL-2 engineering, strategic realignment and external factors led to project termination prior to FEL-3 and FEED execution.
Modeling and Predicting Lignin Dissolution in Ionic Liquids and Separation of Lignin Molecular Weight Fractions using Size Exclusion Chromatography
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Structure of Lipopolysaccharide from Liberibacter crescens Is Low Molecular Weight and Offers Insight into Candidatus Liberibacter Biology
Huanglongbing (HLB) disease, also known as citrus greening disease, was first reported in the US in 2005. Since then, the disease has decimated the citrus industry in Florida, resulting in billions of dollars in crop losses and the destruction of thousands of acres of citrus groves. The causative agent of citrus greening disease is the phloem limited pathogen Candidatus Liberibacter asiaticus. As it has not been cultured, very little is known about the structural biology of the organism. Liberibacter are part of the Rhizobiaceae family, which includes nitrogen-fixing symbionts of legumes as well as the Agrobacterium plant pathogens. To better understand the Liberibacter genus, a closely related culturable bacterium (Liberibacter crescens or Lcr) has attracted attention as a model organism for structural and functional genomics of Liberibacters. Given that the structure of lipopolysaccharides (LPS) from Gram-negative bacteria plays a crucial role in mediating host-pathogen interactions, we sought to characterize the LPS from Lcr. We found that the major lipid A component of the LPS consisted of a pentaacylated molecule with a β-6-GlcN disaccharide backbone lacking phosphate. The polysaccharide portion of the LPS was unusual compared to previously described members of the Rhizobiaceae family in that it contained ribofuranosyl residues. The LPS structure presented here allows us to extrapolate known LPS structure/function relationships to members of the Liberibacter genus which cannot yet be cultured. It also offers insights into the biology of the organism and how they manage to effectively attack citrus trees.
Low Molecular Weight Volatile Organic Compounds Indicate Grazing by the Marine Rotifer Brachionus plicatilis on the Microalgae Microchloropsis salina
Microalgae produce specific chemicals indicative of stress and/or death. The aim of this study was to perform non-destructive monitoring of algal culture systems, in the presence and absence of grazers, to identify potential biomarkers of incipient pond crashes. Here, we report ten volatile organic compounds (VOCs) that are robustly generated by the marine alga, Microchloropsis salina, in the presence and/or absence of the marine grazer, Brachionus plicatilis. We cultured M. salina with and without B. plicatilis and collected in situ volatile headspace samples using thermal desorption tubes over the course of several days. Data from four experiments were aggregated, deconvoluted, and chromatographically aligned to determine VOCs with tentative identifications made via mass spectral library matching. VOCs generated by algae in the presence of actively grazing rotifers were confirmed via pure analytical standards to be pentane, 3-pentanone, 3-methylhexane, and 2-methylfuran. Six other VOCs were less specifically associated with grazing but were still commonly observed between the four replicate experiments. Through this work, we identified four biomarkers of rotifer grazing that indicate algal stress/death. This will aid machine learning algorithms to chemically define and diagnose algal mass production cultures and save algae cultures from imminent crash to make biofuel an alternative energy possibility.
Surface treatment of ultra-high molecular weight polymers
The methods and compounds disclosed herein relate to the surface modification of UHMWPs by means of a catalytic C—H bond insertion catalyst using a rhodium catalysts in conjunction with carbene-generating diazo compounds. The catalytic treatment imparts covalently added functionality to the UHMWPE surface. This functionality acts as an excellent grafting mechanism for grafting, bonding, or adhering further materials to the UHMWPs surface.
Impact of Polymer Molecular Weight on Polymeric Photodiodes
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MOLECULAR-SCALE POLYMER MELTS RESPONSE TO SHEAR IN THE LINEAR AND NON-LINEAR RHEOLOGICAL DOMAINS: AFFECTS OF MOLECULAR WEIGHT AND COMPLEX ARCHITECTURE
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Device and methods for determination of molecular weight distributions of polymers and distributions of other polymer properties without physical separation
Devices and methods for determining the cumulative distribution of a polymer property in a reactor without physical separation of reaction subcomponents. The device includes a means of measuring an instantaneous property of the polymers being produced in a reaction vessel a plurality of times during a polymerization reaction as well as a means of determining the corresponding change in polymer concentration in the reaction vessel between measurements of the instantaneous polymer property The device also includes a means of computing a statistical distribution appropriate to the polymer characteristic and applying the statistical distribution to a recently measured instantaneous value of the polymer property so as to have an instantaneous distribution of the polymer property and a means of adding together the instantaneous distributions of the polymer property in order to obtain the cumulative distribution of the polymer property in the reactor.
Molecular weight growth by the phenyl + cyclopentadienyl reaction.
Abstract not provided.