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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Amine-functionalized porous organic polymers for carbon dioxide capture

Recent developments in CO 2 capture using porous organic polymers (POPs) have received accrescent attention due to their sorbent properties such as high CO 2 uptake capacity and selectivity, tunable chemical structure and permanent porosity. POPs are constructed using two and/or three-dimensional organic monomers (building blocks) linked to each other through covalent bonding, creating high porosity. The pore structure in POPs is exceptionally stable, which leads to their cyclable CO 2 adsorption performance. However, POPs generally suffer from low CO 2 uptake and selectivity due to their interaction with CO 2 in physisorption limits (20–40 kJ mol -1 ). Similar to that in other physisorbents, the CO 2 uptake capacity of POPs further decreases under humid conditions. Pursuant to these limitations, amine functionalization in POPs has resulted in enhanced CO 2 uptake performance with improved CO 2 selectivity over non-polar gases such as N 2 . More importantly, several types of amine-functionalized POPs showed that the CO 2 uptake could remain intact under humid conditions such as in post-combustion flue gas. This review article covers recent developments in amine-functionalized porous organic polymers. Three main categories of amine functionalization, such as direct amine synthesis, amine impregnation and amine grafting, were investigated in detail by considering the effect of amines on the sorbent properties and CO 2 capture performance of POPs. The recent findings in amine-functionalized POPs were investigated including porous polymeric networks (PPNs), covalent organic frameworks (COFs), amine linked POPs, hyper-crosslinked polymers (HCPs), conjugated microporous polymers (CMPs), benzimidazole linked polymers (BILPs), porous aromatic frameworks (PAFs) and polymers of intrinsic microporosity (PIMs).

36 MATERIALS SCIENCE↗
DOE OSTI2020

Precious metal recovery from electronic waste by a porous porphyrin polymer

Significance Electronic waste, also called e-waste, is rapidly becoming a major industrial hazard because of the increased use of circuits and screens. With the right technology, however, this waste could become a sustainable source for precious metals. Such a solution requires selectivity toward the precious metals, as this characteristic is even more important than capacity. A porphyrin-based porous polymer with selective binding shows remarkable selectivity and a reductive mechanism, a combination which makes for record-high recycling of precious metals––particularly gold––from e-waste.

Hong, Yeongran↗
DOE OSTI2023

Functionalized porous organic polymers as uranium nano-traps for efficient uranium extraction

Compositions are provided for efficient uranium extraction, for example from wastewater, seawater, or other water sources. The compositions can include a functionalized porous organic polymer functionalized with one or more uranium binding moieties, e.g. having a plurality of amidoxime or amidrazone groups covalently attached thereto. The compositions can include covalent organic frameworks, porous aromatic frameworks, and various porous organic polymers, especially those having a hierarchical pore size distribution over a range of pore sizes. The compositions can have functional groups such as amidoxime or an amidrazone covalently attached thereto. The hierarchical pore size distribution can be determined based upon at least 60% of the pore sizes in the range of pore sizes having a pore volume of at least 0.01 cm 3 g −1 in the pore size distribution at 77 K. Methods of making the compositions and methods of using the compositions are also provided.

Ma, Shengqian↗
DOE OSTI2020

Leveraging Actinide Hydrolysis Chemistry for Targeted Th and U Separations using Amidoxime-Functionalized Poly(HIPE)s

Polymerized high internal phase emulsions (poly(HIPE)s) are porous polymer monoliths whose synthesis can easily be tailored to allow incorporation of functional units. In this work, nitrile containing poly(HIPE)s have been prepared with either acrylonitrile (AN) or 4-cyanostyrene (4CS) comonomers. Post-synthetic modification of these nitrile-containing poly(HIPE)s yields their corresponding amidoximated analogues, which were studied for actinide uptake. These amidoxime-functionalized, porous polymers were shown to adsorb 95 % Th4+ species from aqueous solution within 30 minutes. In contrast to other amidoxime containing polymers the uptake of UO22+ in these poly(HIPE)s is lower under similar conditions. A critical analysis of actinide separations and high-energy X-ray scattering data provides insight into the polymers’ selectivity, enabled by the uptake of multinuclear Th clusters.

actinides↗
DOE OSTI2022

Carboxylic Group Rotation and Lattice Expansion in a Co 2 (Pyrazine-2,3-Dicarboxylate) 2 (4,4'-Bipyridine) Porous Coordination Polymer Induced by CO 2 Adsorption at Ambient Temperature

Here, a Co 2 (pzdc) 2 (bpy)(H 2 O) m (pzdc: pyrazine-2,3dicarboxylate; bpy: 4,4'-bipyridine) porous coordination polymer (PCP) was studied for CO 2 uptake and concomitant structural changes at ambient temperature. Extended structural characterization included evaluation of lattice parameter changes upon CO 2 adsorption and in situ synchrotron X-ray powder diffraction data. The PCP effective pore size increased by ~2% with gas uptake over the pressure range of 1-50 atm, allowing the adsorption capacity to double. Furthermore, the hysteretic behaviors seen during CO 2 adsorption at moderate pressures are commensurate with the structural changes from synchrotron data. The adsorption and hysteresis occur with rotation of the linking carboxylate groups, and yet only minor changes in unit cell volume (ΔV ≈ 6 Å 3 ) are observed. This contrasts the findings for [Cu 2 (pzdc) 2 (bpy)] n , where a combination of pillar bpy rotations and significant lattice expansion (ΔV ≈ 68 Å(3)) takes place upon hysteretic adsorption of CO 2 . In situ high-temperature X-ray diffraction revealed that the Co(II)-based material has good thermal stability up to ca. 200° C. Finally, the CO 2 uptake also appears to be at a physisorption level, with adsorbent-adsorbate interactions that are ca. 30% stronger than what has been reported for CO 2 adsorption onto [Cu 2 (pzdc) 2 (bpy)] n .

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

Templated synthesis enhances the cobalt adsorption capacity of a porous organic polymer

Divalent transition metals such as Co(II) are important targets for removal from water sources, due to their potential toxicity as well as their high value. In this study, we found that a series of porous organic polymers based on amide-linked tetraphenylmethane units are effective Co(II) ion adsorbents in aqueous solution. To increase the density of Co(II) binding sites, we then developed a templated synthesis in which the branched, rigid monomers are pre-assembled around Co(II) ions prior to polymerization. Furthermore, after polymer formation, the Co(II) template ions are removed to yield a material rich in Co(II) binding sites. Ion adsorption isotherms show that the Co(II)-templated material has an ion adsorption capacity significantly greater than those of the non-templated materials, highlighting the utility of a templated synthetic route. SEM and TEM images show the morphology of the templated polymer to be dramatically different from the non-templated polymers and to be similar in size and shape to the Co(II)–monomer precursors, emphasizing the role of the template ions in directing the formation of the resulting polymer. This guest-templated approach requires no functionalization of the generic monomer and represents a promising synthetic route to high-capacity ion adsorbents for water purification and aqueous separations.

36 MATERIALS SCIENCE↗
NASA NTRS1998

Three-dimensional culture of rat calvarial osteoblasts in porous biodegradable polymers

Neonatal rat calvarial osteoblasts were cultured in 90% porous, 75:25 poly(DL-lactic-co-glycolic acid) (PLGA) foam scaffolds for up to 56 days to examine the effects of the cell seeding density, scaffold pore size, and foam thickness on the proliferation and function of the cells in this three-dimensional environment. Osteoblasts were seeded at either 11.1 x 10(5) or 22.1 x 10(5) cells per cm2 onto PLGA scaffolds having pore sizes in the range of 150-300 or 500-710 microm with a thickness of either 1.9 or 3.2 mm. After 1 day in culture, 75.6 and 68.6% of the seeded cells attached and proliferated on the 1.9 mm thick scaffolds of 150-300 microm pore size for the low and high seeding densities, respectively. The number of osteoblasts continued to increase throughout the study and eventually leveled off near 56 days, as indicated by a quantitative DNA assay. Osteoblast/foam constructs with a low cell seeding density achieved comparable DNA content and alkaline phosphatase (ALPase) activity after 14 days, and mineralization results after 56 days to those with a high cell seeding density. A maximum penetration depth of osseous tissue of 220+/-40 microm was reached after 56 days in the osteoblast/foam constructs of 150-300 microm pore size initially seeded with a high cell density. For constructs of 500-710 microm pore size, the penetration depth was 190+/-40 microm under the same conditions. Scaffold pore size and thickness did not significantly affect the proliferation or function of osteoblasts as demonstrated by DNA content, ALPase activity, and mineralized tissue formation. These data show that comparable bone-like tissues can be engineered in vitro over a 56 day period using different rat calvarial osteoblast seeding densities onto biodegradable polymer scaffolds with pore sizes in the range of 150-710 microm. When compared with the results of a previous study where similar polymer scaffolds were seeded and cultured with marrow stromal cells, this study demonstrates that PLGA foams are suitable substrates for osteoblast growth and differentiated function independent of cell source.

Non-NASA Center↗
DOE OSTI2020

Exploration of advanced porous organic polymers as a platform for biomimetic catalysis and molecular recognition

Nature has long been a dominant source of inspiration in the area of chemistry, serving as prototypes for the design of materials with proficient performance. In this Feature article, we present our efforts to explore porous organic polymers (POPs) as a platform for the construction of biomimetic materials to enable new technologies to achieve efficient conversions and molecular recognition. For each aspect, we first present the chemical basis of nature, followed by depicting the principles and design strategies involved for functionalizing POPs along with a summary of critical requirements for materials, culminating in a demonstration of unique features of POPs. Our endeavours in using POPs to address the fundamental scientific problems related to biomimetic catalysis and adsorption are then illustrated to show their enormous potential and capabilities for applications ranging from concerted catalysis to radionuclide sequestration. To conclude, we present a personal perspective on the challenges and opportunities in this emerging field.

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

Amphiphilic Polyphosphazene for Fluorocarbon Emulsion Stabilization

High internal phase emulsions (HIPEs) have been of great interest for fabricating fluorinated porous polymers having controlled pore structures and excellent physicochemical properties. However, it remains a challenge to prepare stable fluorocarbon HIPEs, due to the lack of suitable surfactants. By randomly grating hydrophilic and fluorophilic side chains to polyphosphazene (PPZ), a comb-like amphiphilic PPZ surfactant with biodegradability is designed and synthesized for stabilizing water/fluorocarbon oil-based emulsions. The hydrophilic–lipophilic balance of PPZs can be controlled by tuning the grating ratio of the two side chains, leading to the preparation of stable water-in-oil HIPEs and oil-in-water emulsions, and the production of fluorinated porous polymers and particles by polymerizing the oil phase. Finally, these fluorinated porous polymers show excellent thermal stability and, due to the hydrophobicity and porous structure, applications in the field of oil/water separation can be achieved.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1998

Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration

We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve, long bone, intestine, or blood vessel.

NASA Discipline Cell Biology↗
NASA NTRS1998

Distributed Pore Chemistry in Porous Organic Polymers

A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The sub-strate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic region, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

Koontz, Steven L.↗
NASA NTRS1999

Distributed Pore Chemistry in Porous Organic Polymers in Tissue Culture Flasks

A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclose. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

Koontz, Steven L.↗
NASA NTRS2000

Cell-Culture Reactor Having a Porous Organic Polymer Membrane

A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphory1choline groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

Koontz, Steven L.↗
NASA NTRS1999

Distributed Pore Chemistry in Porous Organic Polymers

A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge. wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions. and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

Koontz, Steven L.↗
DOE OSTI2021

Dual‐Ion Intercalation and High Volumetric Capacitance in a Two‐Dimensional Non‐Porous Coordination Polymer

Abstract Intercalation is a promising ion‐sorption mechanism for enhancing the energy density of electrochemical capacitors (ECs) because it offers enhanced access to the electrochemical surface area. It requires a rapid transport of ions in and out of a host material, and it must occur without phase transformations. Materials that fulfil these requirements are rare; those that do intercalate almost exclusively cations. Herein, we show that Ni 3 (benzenehexathiol) (Ni 3 BHT), a non‐porous two‐dimensional (2D) layered coordination polymer (CP), intercalates both cations and anions with a variety of charges. Whereas cation intercalation is pseudocapacitive, anions intercalate in a purely capacitive fashion. The excellent EC performance of Ni 3 BHT provides a general basis for investigating similar dual‐ion intercalation mechanisms in the large family of non‐porous 2D CPs.

Banda, Harish↗
DOE OSTI2021

Dual-Ion Intercalation and High Volumetric Capacitance in a Two-Dimensional Non-Porous Coordination Polymer

Intercalation is a promising ion-sorption mechanism for enhancing the energy density of electrochemical capacitors (ECs) because it offers enhanced access to the electrochemical surface area. It requires a rapid transport of ions in and out of a host material, and it must occur without phase transformations. Materials that fulfil these requirements are rare; those that do intercalate almost exclusively cations. Herein, we show that Ni3(benzenehexathiol) (Ni 3 BHT), a non-porous two-dimensional (2D) layered coordination polymer (CP), intercalates both cations and anions with a variety of charges. Whereas cation intercalation is pseudocapacitive, anions intercalate in a purely capacitive fashion. The excellent EC performance of Ni3BHT provides a general basis for investigating similar dual-ion intercalation mechanisms in the large family of non-porous 2D CPs.

36 MATERIALS SCIENCE↗