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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Synthesis of poly(aniline-co-o-toluidine) coatings on copper

The corrosion protective poly(aniline-co-o-toluidine) (PAOT) coatings were synthesized on copper (Cu) by the electrochemical copolymerization of aniline with o-toluidine under cyclic voltammetry conditions. Aqueous oxalate solutions were used as the supporting electrolytes for the synthesis of PAOT coatings on Cu. The resulting coatings were characterized by different spectroscopic techniques, cyclic voltammetry, ultraviolet-visible absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and scanning electron microscopy. The Fourier Transform InfraRed (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR) spectroscopy studies reveal that the copolymerization of aniline and o-toluidine takes place on Cu substrates from an aqueous oxalate solutions and resulting in PAOT copolymer, there are more o-toluidine units than aniline units.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Superabsorbent hydrogel composite based on copolymer cellulose/poly (vinyl alcohol)/CNT

Superabsorbent hydrogels are cross-linked hydrophilic polymers that can absorb and retain a large volume of water, saline solution, or physiological fluids. A distinctive superabsorbent hydrogel composite based on cellulose/ poly (vinyl alcohol)/ carbon nanotubes was successfully synthesized via the graft bio-copolymerization in an aqueous medium with glutaraldehide as a crosslinking agent. The effect of carbon nanotubes (CNT) on water absorption capacity and mechanical properties of superabsorbent composite were particularly investigated. The Fourier transform infrared spectra showed the evidence of copolymerization of hydrogel precursors as well as the interaction of CNT filler with the hydrogel matrices, as indicated by the shifting of peak intensity and position of several functional groups (O-H, C-H sp{sup 3}, C=O, C-N, C-O). The modification of hydrogel surface morphology and porosity owing to CNT insertion was also confirmed by scanning electron microscopy images. The CNT insertion improved the mechanical strength of superabsorbent hydrogel composites. Moreover, insertion of CNT into hydrogel matrix remarkably increased the swelling capacity of superabsorbent composites up to 840%. This huge water absorption capacity of hydrogel composites offers promising applications in development of superabsorbent polymers.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

A Heterogeneous Palladium Catalyst for the Polymerization of Olefins Prepared by Halide Abstraction Using Surface R 3 Si + Species

Abstract The silylium‐like surface species [ i Pr 3 Si][(R F O) 3 Al−OSi≡)] activates (N^N)Pd(CH 3 )Cl (N^N=Ar−N=CMeMeC=N−Ar, Ar=2,6‐bis(diphenylmethyl)‐4‐methylbenzene) by chloride ion abstraction to form [(N^N)Pd−CH 3 ][(R F O) 3 Al−OSi≡)] ( 1 ). A combination of FTIR, solid‐state NMR spectroscopy, and reactions with CO or vinyl chloride establish that 1 shows similar reactivity patterns as (N^N)Pd(CH 3 )Cl activated with Na[B(Ar F ) 4 ]. Multinuclear 13 C{ 27 Al} RESPDOR and 1 H{ 19 F} S‐REDOR experiments are consistent with a weakly coordinated ion‐pair between (N^N)Pd−CH 3 + and [(R F O) 3 Al−OSi≡)]. 1 catalyzes the polymerization of ethylene with similar activities as [(N^N)Pd−CH 3 ] + in solution and incorporates up to 0.4 % methyl acrylate in copolymerization reactions. 1 produces polymers with significantly higher molecular weight than the solution catalyst, and generates the highest molecular weight polymers currently reported in copolymerization reactions of ethylene and methylacrylate.

Gao, Jiaxin↗
DOE OSTI2022

A Heterogeneous Palladium Catalyst for the Polymerization of Olefins Prepared by Halide Abstraction Using Surface R 3 Si + Species

The silylium-like surface species [ i Pr 3 Si][(R F O) 3 Al-OSi≡)] activates (N^N)Pd(CH 3 )Cl (N^N=Ar-N=CMeMeC=N-Ar, Ar=2,6-bis(diphenylmethyl)-4-methylbenzene) by chloride ion abstraction to form [(N^N)Pd-CH 3 ][(R F O) 3 Al-OSi≡)] ( 1 ). A combination of FTIR, solid-state NMR spectroscopy, and reactions with CO or vinyl chloride establish that 1 shows similar reactivity patterns as (N^N)Pd(CH 3 )Cl activated with Na[B(Ar F ) 4 ]. Multinuclear 13 C{ 27 Al} RESPDOR and 1 H{ 19 F} S-REDOR experiments are consistent with a weakly coordinated ion-pair between (N^N)Pd-CH 3 + and [(R F O) 3 Al-OSi≡)]. 1 catalyzes the polymerization of ethylene with similar activities as [(N^N)Pd-CH 3 ] + in solution and incorporates up to 0.4% methyl acrylate in copolymerization reactions. 1 produces polymers with significantly higher molecular weight than the solution catalyst, and generates the highest molecular weight polymers currently reported in copolymerization reactions of ethylene and methylacrylate.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Hydroxycinnamate Conjugates as Potential Monolignol Replacements: In vitro Lignification and Cell Wall Studies with Rosmarinic Acid

The plasticity of lignin biosynthesis should permit the inclusion of new compatible phenolic monomers, such as rosmarinic acid (RA) and analogous catechol derivatives, into cell-wall lignins that are consequently less recalcitrant to biomass processing. In vitro lignin polymerization experiments revealed that RA readily underwent peroxidase-catalyzed copolymerization with monolignols and lignin oligomers to form polymers with new benzodioxane inter-unit linkages. Incorporation of RA permitted extensive depolymerization of synthetic lignins by mild alkaline hydrolysis, presumably by cleavage of ester intra-unit linkages within RA. Copolymerization of RA with monolignols into maize cell walls by in situ peroxidases significantly enhanced alkaline lignin extractability and promoted subsequent cell wall saccharification by fungal enzymes. Incorporating RA also improved cell wall saccharification by fungal enzymes and by rumen microflora even without alkaline pretreatments, possibly by modulating lignin hydrophobicity and/or limiting cell wall cross-linking. Consequently, we anticipate that bioengineering approaches for partial monolignol substitution with RA and analogous plant hydroxycinnamates would permit more efficient utilization of plant fiber for biofuels or livestock production.

Yuki, Tobimatsu↗
DOE OSTI2023

Unveiling the Role of Compositional Drifts on the Tack of Pressure‐Sensitive‐Adhesives

Abstract Pressure‐sensitive‐adhesives (PSAs) are pervasive in electronic, automobile, packaging, and biomedical applications due to their ability to stick to numerous surfaces without undergoing chemical reactions. These materials are typically synthesized by the free radical copolymerization of alkyl acrylates and acrylic acid, leading to an ensemble of polymer chains with varying composition and molecular weight. Here, reversible addition−fragmentation chain‐transfer (RAFT) copolymerizations in a semi‐batch reactor are used to tailor the molecular architecture and bulk mechanical properties of acrylic copolymers. In the absence of cross‐links, the localization of acrylic acid toward the chain ends leads to microphase separation, creep resistance, and enhanced tack. However, in the presence of Al(acac) 3 crosslinker, the creep resistance remains unchanged and mostly the large‐strain mechanical properties are affected. This behavior is attributed to microphase separation, but also to a change in the energy required to break physical associations, and untangle and elongate associative polymers to large deformations.

Polymer Science↗
DOE OSTI2017

Crosslinked anion exchange membranes with connected cations

The selective transport of ions has crucial importance in biological systems as well as modern-day energy devices, such as batteries and fuel cells, and water purification membranes. Control over ion movement can be exerted by ligation, ion channel dimensions, solvation, and electrostatic interactions. Polyelectrolyte hydrogels can provide aligned pathways for counter ion transport but lack mechanical integrity, while polyelectrolyte membranes typically suffer from the absence of an ion transport channel network. To develop polymer membranes for improved ion transport, we present the design of a novel material that combines the advantages of aligned pathways found in polyelectrolyte hydrogel and mechanical robustness in conventional membranes. The ionic species were organized via controlled copolymerization of a quaternizable monomer. Additionally, dimensional stability was then incorporated through a cast/crosslinking method to lock in the network of connected cationic groups. This strategy resulted in dramatically enhanced ion transport, as characterized by ionic conductivities (>80 mS/cm for Cl-, and approximate to 200 mS/cm for OH-).

Zhang, Wenxu↗
DOE OSTI2016

A microstructural analysis of isoprenol ether-based polycarboxylates and the impact of structural motifs on the dispersing effectiveness

Generally, polycarboxylate superplasticizers (PCEs) are synthesized via aqueous free radical copolymerization. The conditions during copolymerization such as relative reactivity and feeding mode and ratio of monomers can cause different monomer sequences in the final product. In this study, the sequence of monomers in PCE polymers synthesized from acrylic acid and isoprenyloxy polyethylene glycol (IPEG) macromonomer was characterized by {sup 13}C nuclear magnetic resonance (NMR) spectroscopy. Three different triads of monomer sequences (EAE, AAE and AAA; E = ether, A = acid monomer) were detected. It was found that IPEG PCEs predominantly contain the structural motifs of AAE and EAE, and less of AAA. Higher additions of acrylic acid do not incorporate into the structure of PCE, but convert to HMW polyacrylate as by-product instead. A PCE with optimal dispersing effectiveness was achieved at high contents of IPEG macromonomer, a molecular weight (M{sub w}) around 40,000 Da and narrow molecular weight distribution.

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

Random copolymer of poly(polyethylene glycol methyl ether)methacrylate as tunable transition temperature solid-solid phase change material for thermal energy storage

Polymer based phase change materials (PCM) for thermal energy storage (TES) applications have gained some attention recently due to their high stability and potential solid to solid phase transition. In this work, we are the first to utilize a simple copolymerization strategy for static tunability transition temperature (T t ) of polymeric PCM. The copolymerization between short and long side chain polyethylene glycol based methacrylate polymers was designed to tune T t with minimum impact on their energy density. Polarized optical microscope and x-ray techniques were also used to understand the relationship between crystal structure and T t of different copolymer composition which was discussed in the context. The solid to solid transition polymeric PCM were successfully developed with tunable T t ranged from 18 °C to 35 °C which is suitable toward building envelop applications.

14 SOLAR ENERGY↗
DOE OSTI2025

Late Metal Sandwich Catalysts for Olefin Polymerization

Polyolefins are by far the most ubiquitous industrially produced polymers and are primarily produced by early transition metal catalysts. These catalysts are not functional group tolerant, and copolymerization of ethylene and polar vinyl monomers is quite challenging. Furthermore, early metal catalysts convert ethylene to linear polyethylene, and introduction of branches requires addition of comonomers. In this Account, we describe our efforts in designing and implementing new Pd(II) and Ni(II) olefin polymerization catalysts based on mechanistic understanding of the chain growth process. Here, the original hindered nickel- and palladium-aryl-substituted diimine complexes were discovered in 1995. The key to the success of these now “classic” systems in generating high polymers rather than dimers or oligomers was realizing that incorporation of ortho-disubstituted aryl groups partially blocks the axial sites of the metal and thus retards the rate of chain transfer relative to propagation. Two key features of these late metal catalysts distinguish them from early metal complexes. First, they tolerate certain functional groups, which allows copolymerization of olefins with polar comonomers. Second, they can form a branched polymer from ethylene without the need to add α-olefin comonomers. Importantly, for nickel catalysts, branching levels can be modulated by changing reaction conditions, such as temperature and monomer pressure.

Catalysts↗
DOE OSTI2016

Amidine-Mediated Zwitterionic Ring-Opening Polymerization of N -Alkyl N -Carboxyanhydride: Mechanism, Kinetics, and Architecture Elucidation

Zwitterionic ring-opening polymerization (ZROP) of N-butyl N-carboxyanhydrides (Bu-NCAs) has been investigated using 1,8-diazabicycloundec-7-ene (DBU), a bicyclic amidine initiator. It was found that poly(N-butylglycine)s (PNBGs) with molecular weight (M n ) in the 3.5–32.4 kg mol –1 range and polydispersity index (PDI) in the 1.02–1.12 range can be readily obtained by systematically varying the initial monomer to initiator feed ratio. The polymerization exhibits characteristics of a controlled polymerization, as evidenced by the linear increase of polymer molecular weight with conversion and the successful enchainment experiments. Kinetic studies revealed that the reaction is first-order dependent on the monomer and the DBU concentration. The rate of initiation is comparable to that of the propagation. Random copolypeptoids of poly[(N-propargylglycine)-r-(N-butylglycine)]s [P(NPgG-r-NBG)s] were also synthesized by DBU-mediated copolymerization of Bu-NCA and N-propargyl N-carboxyanhydride (Pg-NCA). Subsequent grafting with azido-terminated poly(ethylene glycol) (PEG) produces bottlebrush copolymers. Analysis of bottlebrush copolymer samples using atomic force microscopy (AFM) revealed a surface morphology of toroid-shaped nanostructures, consistent with the polypeptoid backbone having cyclic architecture. Here, small-angle neutron scattering (SANS) characterization of the bottlebrush polymer ensemble in solution also confirms the cyclic architecture of the polypeptoid backbones.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Tuning Copolymer Microstructure Using Ring-Opening Cross-Metathesis Polymerization

The capability of ring-opening cross-metathesis (RO/CM) polymerization to produce alternating copolymers was studied. By treating commercial polybutadiene (PB) with bulky oxanorbornene monomers and Ru-based olefin metathesis catalysts, alternating copolymers were produced under mild conditions with high sequence fidelities. Here, we found that alternating copolymers could be produced starting from a variety of butadiene sources including PB, cyclooctadiene (COD), or t,t,t-1,5,9-cyclododecatriene (CDT), highlighting for the first time the kinetic pathway independence of this process. Kinetic copolymerization analysis of an oxanorbonene monomer with CDT revealed that much higher monomer conversions were obtained compared with the analogous homopolymerizations and showed evidence of alternating monomer incorporation. Copolymerization of these monomers also enabled good control when targeting different molecular weights. Copolymer thermal analysis revealed a strong correlation between thermal behavior and alternating sequence fidelity, providing a second lever beyond composition to tune thermal behavior. These data demonstrate that a broad variety of polymer microstructures can be accessed via RO/CM polymerization and highlight the potential of CDT in alternating copolymer synthesis.

Foster, Jeffrey C. [Oak Ridge National Laboratory ↗
DOE OSTI2017

Distinctive Stereochemically Linked Cooperative Effects in Bimetallic Titanium Olefin Polymerization Catalysts

The complex (μ-Me 2 C-3,3'){(η 5 -cyclopentadienyl)[1-Me 2 Si-( t BuN)](TiMe 2 )} 2 (3) was prepared as a new binuclear catalyst motif for homogeneous olefin polymerization. Complex 3 exists as rac-3 and meso-3 diastereomers, which can be separated and characterized by solution NMR spectroscopy and single-crystal X-ray diffraction. While meso-3 has high thermal stability, rac-3 undergoes thermolysis in solution to quantitatively form the dimeric methylidene complex (μ-Me 2 C-3,3'){(η 5 -cyclopentadienyl)[1-Me 2 Si( t BuN)][(μ-CH 2 )Ti]}2 (rac-4). Activation of rac-3 and meso-3 with 1 equiv of Ph 3 C + B(C 6 F 5 ) 4 – yields [(μ-CMe 2 -3,3'){(η 5 -cyclopentadienyl)[1-Me 2 Si( t BuN)]} 2 (μ-CH 2 )(μ-CH 3 )Ti 2 ] + B(C 6 F 5 ) 4 – (5; rac-5 and meso-5, respectively). Interestingly, meso-5 is stable in the presence of an additional 1 equiv of Ph 3 C + B(C 6 F 5 ) 4 –, while rac-5 reacts to yield rac-[(μ-CMe2-3,3'){(η5-cyclopentadienyl)[1-Me2Si(tBuN)]}2(μ-CH2)[(TiCH3)(Ti-η1-Ph3C)]2+[B(C6F5)4–]2 (rac-6) as indicated by multinuclear NMR spectroscopy and DFT computation. meso-3 reacts with 2 equiv of B(C 6 F 5 ) 3 to yield meso-[(μ-CMe 2 -3,3'){(η 5 -cyclopentadienyl)[1-Me 2 Si( t BuN)]} 2 (μ-CH 2 )(μ-CH 3 )Ti 2 ]+MeB(C 6 F 5 ) 3 – (meso-7) containing the same meso-5 cation but with a MeB(C 6 F 5 ) 3 –counteranion. These findings, along with catalytic results, indicate that rac-3 and meso-3 remain structurally intact during polymerization, consistent with the observed diastereoselectivity effects. Under identical ethylene/1-octene copolymerization conditions, only activated bimetallic rac-3 produces appreciable polymer, with meso-3 exhibiting low activity, but both yield polymer with a branch density >2× that of the monometallic control [(3- t Bu-C 5 H 3 )SiMe 2 N t Bu]TiMe 2 (Ti 1 ). In ethylene/styrene copolymerizations, rac-3 produces polymers with 3.1× higher M n and 2.1× greater styrene incorporation versus Ti 1 , while meso-3 catalyzes only ethylene-free styrene homopolymerization. In 1-octene homopolymerizations, meso-3 + B(C 6 F 5 ) 3 (i.e., meso-7) produces highly isotactic poly-1-octene (mmmm 91.7%), while rac-3 + Ph 3 C + B(C 6 F 5 ) 4 – (i.e., rac-5), rac-3 + B(C 6 F 5 ) 3 (i.e., rac-7), and meso-3 + Ph 3 C + B(C 6 F 5 ) 4 – (i.e., meso-5) produce only atactic poly-1-octene. In conclusion, these bimetallic polymerization catalysts exhibit distinctive cooperative effects influencing product M n , tacticity, and comonomer selection, demonstrating that binuclear catalyst stereochemical factors are significant.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Successful Coupling of a Bis-Amidoxime Uranophile with a Hydrophilic Backbone for Selective Uranium Sequestration

The amidoxime group (-RNH2NOH) has long been used to extract uranium from seawater on account of its high affinity toward uranium. The development of tunable sorbent materials for uranium sequestration remains a research priority as well as a significant challenge. Herein, we report the design, synthesis, and uranium sorption properties of bis-amidoxime-functionalized polymeric materials (BAP 1–3). Bifunctional amidoxime monomers were copolymerized with an acrylamide cross-linker to obtain bis-amidoxime incorporation as high as 2 mmol g–1 after five synthetic steps. The resulting sorbents were able to uptake nearly 600 mg of uranium per gram of polymer after 37 days of contact with a seawater simulant containing 8 ppm uranium. Moreover, the polymeric materials exhibited low vanadium uptake with a maximum capacity of 128 mg of vanadium per gram of polymer. This computationally predicted and experimentally realized selectivity of uranium over vanadium, nearly 5 to 1 w/w, is one of the highest reported to date and represents an advancement in the rational design of sorbent materials with high uptake capacity and selectivity.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Nanoscale Miscibility in In Situ Polymerized Hybrid Electrolytes Speeds Up Ion Dynamics and Enables Stable Cycling of Li Metal Batteries

While the potential use of copolymerized electrolytes in Li metal batteries is subject to intense investigation, the fundamental understanding of the nanoscale domain formation and its effect on Li + transport is still lacking. In this study, we investigated the correlation between the Li + transport mechanism and the miscibility of monomers in polymer blend electrolytes derived from the in situ copolymerization of methyl methacrylate (MMA) and vinylene carbonate (VC) in the presence of polyethylene glycol dimethyl ether (PEGDME) plasticizer and bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. The addition of a polar short chain plasticizer reduced the dynamic and structural heterogeneities of the electrolyte. Small-angle X-ray scattering (SAXS) measurements and coarse-grained molecular dynamics (MD) simulations were used to investigate the nanoscale structure of the electrolytes. The distribution of relaxation times corresponding to the three distinct diffusion mechanisms of the free and interfacial Li + ions at the copolymer/plasticizer and electrolyte/SEI boundaries was analyzed in a broad temperature range to elucidate the Li + transport mechanism. Furthermore, the chemical composition of the SEI and the contribution of a ceramic lithium lanthanum zirconium oxide (LLZO, Li 7 La 3 Zr 2 O 12 ) phase on the interfacial resistance, salt degradation, and SEI stability were studied by X-ray photoelectron spectroscopy (XPS) depth profile analysis and electrochemical testing.

Li metal↗
DOE OSTI2025

One Step Block-like Copolymers from an Upcycled Monomer Using Ring-Opening Metathesis Polymerization

Block-like copolymers can be readily synthesized in one step using monomers with widely separated reactivity ratios. Here, we show that trans,trans,trans-1,5,9-cyclododecatriene (CDT), produced from polybutadiene via cyclodepolymerization (CDP), undergoes gradient copolymerization via ring-opening metathesis polymerization (ROMP) with a selected norbornene monomer to produce a block-like copolymer that exhibits bulk nanophase separation and excellent thermomechanical performance. These data highlight a new ROMP copolymerization system with a sharp compositional drift and introduce a simple pathway to convert waste plastic into a valuable building block for high-value thermoplastic materials.

block copolymer↗
DOE OSTI2022

Effect of the Lignin Structure on the Physicochemical Properties of Lignin-Grafted-Poly(ε-caprolactone) and Its Application for Water/Oil Separation

Lignin-grafted poly(ε-caprolactone) copolymers (lignin-g-PCLs) have shown wide application potentials in coatings, biocomposites, and biomedical fields. However, the structural heterogeneity of lignin affecting the structures and properties of lignin-g-PCL has been scarcely investigated. In this study, kraft lignin is fractionated into four precursors, namely, F ins , F1, F2, and F3, with declining molecular weights and increased hydroxyl contents. Lignin-g-PCLs are synthesized via ring-opening polymerization of ε-caprolactone with lignin and characterized by GPC, FTIR, 1 H and 31 P NMR, DSC, TGA, and iGC. The mechanical properties, UV barrier, and enzymatic biodegradability of the lignin-g-PCLs are evaluated. Results show that lignin with a higher molecular weight and aliphatic OH favors the copolymerization, leading to lignin-g-PCLs with longer PCL arms. Moreover, lignin incorporation improves the thermal stability, hydrophobicity, and UV-blocking ability but reduces the lipase hydrolyzability of the copolymers. We also demonstrated that the lignin-g-PCL-coated filter paper could successfully separate chloroform–, petroleum ether–, and hexane–water mixtures with an efficiency up to 99.2%. The separation efficiency remains above 90% even after 15 cycles. The structural differences of copolymers derived from the fractionation showed minimal influence on the separation efficiency. This work provides new insights into lignin-based copolymerization and the versatility of lignin valorization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗