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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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The Importance of Bulk Viscoelastic Properties in “Self-Healing” of Acrylate-Based Copolymer Materials
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Ion transport on self-assembled block copolymer electrolytes with different side chain chemistries
Hydrophobic alkyl side chains steer water toward the charge-ion pair, giving rise to large interconnected water clusters that promote ion conduction.
A user-friendly plug-and-play cyclic olefin copolymer-based microfluidic chip for room-temperature, fixed-target serial crystallography
Over the past two decades, serial X-ray crystallography has enabled the structure determination of a wide range of proteins. With the advent of X-ray free-electron lasers (XFELs), ever-smaller crystals have yielded high-resolution diffraction and structure determination. A crucial need to continue advancement is the efficient delivery of fragile and micrometre-sized crystals to the X-ray beam intersection. This paper presents an improved design of an all-polymer microfluidic `chip' for room-temperature fixed-target serial crystallography that can be tailored to broadly meet the needs of users at either synchrotron or XFEL light sources. The chips are designed to be customized around different types of crystals and offer users a friendly, quick, convenient, ultra-low-cost and robust sample-delivery platform. Compared with the previous iteration of the chip [Gilbile et al. (2021), Lab Chip , 21 , 4831–4845], the new design eliminates cleanroom fabrication. It has a larger imaging area to volume, while maintaining crystal hydration stability for both in situ crystallization or direct crystal slurry loading. Crystals of two model proteins, lysozyme and thaumatin, were used to validate the effectiveness of the design at both synchrotron (lysozyme and thaumatin) and XFEL (lysozyme only) facilities, yielding complete data sets with resolutions of 1.42, 1.48 and 1.70 Å, respectively. Overall, the improved chip design, ease of fabrication and high modifiability create a powerful, all-around sample-delivery tool that structural biologists can quickly adopt, especially in cases of limited sample volume and small, fragile crystals.
Shaping Symmetry and Molding Morphology of Triply-Periodic Assemblies via Molecular Design of Block Copolymers
The research performed integrated and advanced state-of-the-art theoretical methods for geometrically-complex BCP assembly (Grason), synthesis of precisely-defined BCP architectures (Coughlin), and quantitative and multi-scale approaches to morphological characterization of BCP assembly (Thomas).
Cyclic Olefin Copolymer based Alkaline Exchange Polymers and Reinforced Membranes
In this project, a team of researchers from Rensselaer Polytechnic Institute developed high performance, low-cost alkaline conductors which can improve efficiency and lower cost of energy storage and conversion technology. The Rensselaer Polytechnic Institute team has developed a highly ion conductive, chemically stable, and mechanically durable alkaline membrane materials. Such membranes will serve as a critical component in electrochemical devices when energy is generated from renewable sources (e.g., sun and wind) or hydrogen fuel. The use of alkaline membrane in electrochemical reactions allows us to replace expensive platinum catalysts with less expensive, earth abundant metals as catalysts, offering huge economic advantages in renewable energy technology.
Ion-Selective Membrane Derived from Ionic Block Copolymers with Controlled Nanostructure for Non-Aqueous Redox Flow Batteries
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COPOLYMER COMPOSITES FOR HIGH VOLTAGE INSULATION WRAPS FOR SUPERCONDUCTING MAGNET COILS
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Dichlorinated Dithienylethene-Based Copolymers for Air-Stable n-Type Conductivity and Thermoelectricity
Here, two donor-acceptor polymers were obtained by coupling difluoro- and dichloro-substituted forms of the electron-deficient unit BDOPV and the relatively weak donor moiety dichlorodithienylethene (ClTVT). The conductivity and power factors of doped devices are different for the chlorinated and fluorinated BDOPV polymers. High electron conductivity of 38.3 and 16.1 S cm -1 were obtained from the chlorinated and fluorinated polymers with N-DMBI, respectively, and 12.4 and 2.4 S cm -1 were obtained from the chlorinated and fluorinated polymers with CoCp 2 , respectively, from drop-cast devices. The corresponding power factors are 22.7, 7.6, 39.5 and 8.0 μW m -1 K -2 , respectively. Doping of PClClTVT with N-DMBI results in excellent air-stability; the electron conductivity of devices with 50 mol% N-DMBI as dopant remained up to 4.9 S m -1 after 222 days in the air, the longest for an n-doped polymer stored in air, with a thermoelectric power factor of 9.3 μW m -1 K -2 . However, the conductivity of PFClTVT-based devices can hardly be measured after 103 days. These observations are consistent with morphologies determined by grazing incidence wide angle X-ray scattering (GIWAXS) and atomic force microscopy (AFM). The results demonstrate that chemical structures leading to dense and ordered packing can enhance electron conductivity and air stability of n-type donor-acceptor polymers.
Solution–Doped Donor–Acceptor Copolymers Based on Diketopyrrolopyrrole and 3, 3'–Bis (2–(2–(2–Methoxyethoxy) Ethoxy) ethoxy)–2, 2'–Bithiophene Exhibiting Outstanding Thermoelectric Power Factors with p –Dopants
The design of polymeric semiconductors exhibiting high electrical conductivity (σ) and thermoelectric power factor (PF) will be vital for flexible large-area electronics. In this work, four polymers based on diketopyrrolopyrrole (DPP), 2,3-dihydrothieno[3,4-b][1,4]dioxine (EDOT), thieno[3,2-b]thiophene (TT), and 3, 3'-bis (2-(2-(2-methoxyethoxy) ethoxy) ethoxy)-2, 2'-bithiophene (MEET) are investigated as side-chains, with the MEET polymers newly synthesized for this study. These polymers are systematically doped with tetrafluorotetracyanoquinodimethane ( F 4 TCNQ), CF3SO3H, and the synthesized dopant Cp(CN) 3 -(COOMe) 3 , differing in geometry and electron affinity. The DPP-EDOT-based polymer containing MEET as side-chains exhibits the highest conductivity (σ) ≈700 S cm–1 in this series with the acidic dopant (CF 3 SO 3 H). This polymer also shows the lowest oxidation potential by cyclic voltammetry (CV), the strongest intermolecular interactions evidenced by differential scanning calorimetry (DSC), and has the most oxygen-based functionality for possible hydrogen bonding and ionic screening. Other polymers exhibit high σ ≈300–500 S cm–1 and power factor up to 300 µW m –1 K –2 . The mechanism of conductivity is predominantly electronic, as validated by time-dependent conductance studies and transient thermo voltage monitoring over time, including for those doped with the acid. Furthermore, these materials maintain significant thermal stability and air stability over ≈6 weeks. Density functional theory calculations reveal molecular geometries and inform about frontier energy levels. Raman spectroscopy, in conjunction with scanning electron microscopy (SEM-EDS) and x-ray diffraction, provides insight into the solid-state microstructure and degree of phase separation of the doped polymer films. Infrared spectroscopy enables this study to further quantify the degree of charge transfer from polymer to dopant.
Stereochemically‐Controlled Fluorinated Copolymers for Selectively Permeable Barrier Applications
Selective oxygen permeability coupled with low water vapor transmission is essential for biomedical and packaging applications requiring controlled oxygen flux under humid conditions. However, most high‐performance barrier polymers depend on perfluoroalkyl substances (PFAS), whose persistence and regulatory restrictions limit their long‐term applicability. We designed a series of stereocontrolled thiol‐yne‐based polyesters, including both fluorinated and non‐fluorinated variants, for selective oxygen permeability with considerable water barrier performance. Tailoring polymer crystallinity and morphology tuned both oxygen transport and mechanical properties. Fluorinated polymers demonstrated enhanced hydrophobicity and water resistance while maintaining oxygen diffusivity within a range relevant to oxygen‐sensing applications. Structure–property relationships were elucidated through small‐ and wide‐angle X‐ray scattering, revealing semi‐crystalline domains influenced by fluorine content and dithiol chain length. Barrier performance was rigorously evaluated via water vapor transmission rate and dynamic vapor sorption, showing reduced water uptake with increasing dithiol monomer length and crystallinity. In conclusion, this work introduces a PFAS‐free alternative to conventional barrier materials and establishes a tunable materials platform with potential relevance for biomedical devices and packaging systems requiring controlled oxygen permeability.
Discrete, Shallow Doping of Semiconductors via Cylinder-Forming Block Copolymer Self-Assembly
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Effect of hydration on morphology of thin phosphonate block copolymer electrolyte membranes studied by electron tomography
The morphological changes of phosphonate polypeptoid electrolyte membranes, poly-N-(2-ethyl)hexylglycine-block-poly-N-phosphonomethylglycine (pNeh m -b-pNpm n ), in hydrated and dry states were characterized by cryogenic transmission electron microscopy (cryo-TEM) and cryogenic electron tomography (cryo-ET). The analysis of 3D tomograms revealed that the pNeh 9 -b-pNpm 9 thin films absorbed a large amount of water, resulting in the formation of membranes that were nearly flat and giant multicompartment vesicles dispersed in the water phase. A simple lamellar phase appeared when the films were dried. In contrast, pNeh 18 -b-pNpm 18 thin films absorbed little water and formed small highly curved unilamellar and multilamellar vesicles. Water was located mainly outside the closely-packed vesicles. When water was removed by drying, the walls of adjacent vesicles collapsed to form honeycomb-like capsules. Here, the changes in domain size reflected changes in chain conformations. The pNpm9 blocks were saturated by water and fully extended, while pNpm 18 blocks were neither saturated by water nor fully extended. In addition, the thicknesses of hydrophobic blocks in the hydrated films of both pNeh 9 -b-pNpm 9 and pNeh 18 -b-pNpm 18 were smaller than those in the dry films, reflecting an increase of the average distance between the neighboring junctions of polypeptoid molecules.
Liquid-to-solid transitions in nanoparticle-filled brush block copolymer composites
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Energetic Copolymers From LLM-105 and Aliphatic Isocyanates
Energetic polymers typically feature fuel-rich backbones with pendant oxidizing explosophores, which are used to modify pressure and temperature characteristics in energetic formulations. However, these pendant explosophores generally increase sensitivity and decrease the thermal stability of the polymer in the condensed phase. Direct polymerization of insensitive high explosives (IHEs) bearing polymerizable functionalities, such as amines, provides a synthetic platform for deriving tunable energetic materials. Here, this work demonstrates the first direct polymerization of the IHE 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) with aliphatic isocyanate comonomers to yield an energetic copolyurea (PUa1) and an energetic copolyurea network (PUa2). 1 H and 13 C nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) confirm copolyurea synthesis. PUa1 exhibited branching reactions commonly found in polyurea syntheses, and these side reactions were suppressed in PUa2 through use of a polyfunctional isocyanate. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) demonstrate the energetic IHE based polyurea preserves the energetic decomposition of the parent monomer LLM-105 in PUa1 (1203 J g −1 ) and PUa2 (687 J g −1 ), albeit with reduced thermal stability with peak decomposition temperatures of 235°C and 233°C, respectively. This work presents a new approach for generating energetic polymers from IHE cores with tunable energetic, thermal, and structural characteristics.
Effect of side chain and backbone length on lamellar spacing in polystyrene‐block‐poly(dimethyl siloxane) brush block copolymers
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