Synthesis and Characterization of Anion-Exchange Membranes Using Semicrystalline Triblock Copolymers in Ordered and Disordered States
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99 GENERAL AND MISCELLANEOUS↗
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Results for “block copolymers”
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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Tuning the Mechanical Properties of Crosslinked Copolymers via Sequence and Solvent‐Selective Swelling for Vat Photopolymerization
Block copolymers (BCPs) offer distinct advantages for vat photopolymerization by enabling mechanically programmable network structures through microphase-separated morphologies that can be kinetically trapped during curing, yielding properties unattainable in homogeneous resins. However, the respective roles of repeat-unit sequence and solvent environment, together with their interplay in directing network formation and mechanical performance, remain unclear. Here, we synthesize a series of CO 2 -based polycarbonate copolymers comprising a crosslinkable glassy poly(vinyl cyclohexene carbonate) (PVCHC, A block) and a non-crosslinkable soft poly(propylene carbonate) (PPC, B block). The polymer sequence is systematically varied (ABA, BAB, and statistical), and solvent choice controls block-selective swelling to jointly control gelation behavior, microphase morphology, and mechanical response through changes in the accessibility and local environment of photocrosslinkable vinyl groups during network formation, as revealed by photorheology and small angle x-ray scattering. By tuning polymer sequence and curing solvent, we transform nominally identical formulations from brittle to highly ductile materials, achieving a three-orders-of-magnitude range in toughness (0.003 to 9.1 MJ m −3 ). These results establish clear structure–processing–property relationships and identify polymer sequence and selective solvation as powerful strategies for programming both printability and performance of block copolymer resins for additive manufacturing.
additive manufacturing↗
Novel High Efficient Organic Photovoltaic Materials: Final Summary of Research
The objectives and goals of this project were to investigate and develop high efficient, lightweight, and cost effective materials for potential photovoltaic applications, such as solar energy conversion or photo detector devices. Specifically, as described in the original project proposal, the target material to be developed was a block copolymer system containing an electron donating (or p-type) conjugated polymer block coupled to an electron withdrawing (or n-type) conjugated polymer block through a non-conjugated bridge unit. Due to several special requirements of the targeted block copolymer systems, such as electron donating and withdrawing substituents, conjugated block structures, processing requirement, stability requirement, size controllability, phase separation and self ordering requirement, etc., many traditional or commonly used block copolymer synthetic schemes are not suitable for this system. Therefore, the investigation and development of applicable and effective synthetic protocols became the most critical and challenging part of this project. During the entire project period, and despite the lack of a proposed synthetic polymer postdoctoral research associate due to severe shortage of qualified personnel in the field, several important accomplishments were achieved in this project and are briefly listed and elaborated. A more detailed research and experimental data is listed in the Appendix.
Sun, Sam↗
Interfacial Response and Structural Adaptation of Structured Polyelectrolyte Thin Films
Ionizable block copolymers with distinctive block characteristics display the diversity crucial for the design of macromolecules for targeted applications. In contrast to van der Waals copolymers, their interfaces, which are critical to their function, consist of nanodomains, each of a different nature and thus unique interfacial behavior. Here, the interfacial response of a symmetric block copolymer with a sulfonated polystyrene polyelectrolyte center, tethered to polyethylene-r-propylene and terminated by poly(t-butyl styrene) is probed as polymer films are exposed to three polar solvents, water, propanol, and tetrahydrofuran (THF), using molecular dynamics simulations. Each of the solvents captures a distinctive interaction with the individual blocks. We find that at the film boundary, the interfacial response is initially dominated by that of the hydrophobic blocks to all solvents. At later times, the solvent distribution among the blocks, where water molecules associate predominantly with the sulfonated groups and propanol and THF reside at multiple different sites, determines the chemical composition and the polymer conformation at the interface. Altogether, these simulations provide the first direct molecular insight into the interfacial response of ionizable copolymers.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Polymerizations of 2-(Trimethylsilyl)ethanesulfonyl-activated aziridines
A novel N-sulfonyl aziridine, N-((2-(trimethylsilyl)ethyl)sulfonyl)-2-methyl-aziridine (SES-MeAz) was synthesized, and its controlled anionic ring-opening polymerization to form poly(SES-MeAz) studied. The desulfonylation of poly(SES-MeAz)s can be achieved under mild conditions, with tetrabutylammonium fluoride (TBAF) to form polypropylene imine (PPI), although purification of the PPI was not completely successful. The block copolymer p(pTs-MeAz)-b-p(SES-MeAz), (pTs-MeAz = N-para-tosyl-2-methyl-aziridine) was prepared by a sequential polymerization. The desulfonylation of the block copolymer is the first example of the selective removal of a sulfonyl protecting group from a poly(sulfonylazirdine) block copolymer and this is the first formation of a polysufonylaziridine-block-polypropylene imine copolymer. Three-armed star-shaped poly(SES-MeAz)s were also successfully synthesized and exhibited improved solubility compared with linear poly(SES-MeAz)s.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Symmetry-Breaking and Self-Sorting in Block Copolymer-Based Multicomponent Nanocomposites
Co-assembly of inorganic nanoparticles (NPs) and nanostructured polymer matrix represents an intricate interplay of enthalpic or entropic forces. Particle size largely affects the phase behavior of the nanocomposite. Theoretical studies indicate that new morphologies would emerge when the particles become comparable to the soft matrix's size, but this has rarely been supported experimentally. By designing a multicomponent blend composed of NPs, block copolymer-based supramolecules, and small molecules, a 3-D ordered lattice beyond the native BCP's morphology was recently reported when the particle is larger than the microdomain of BCP. The blend can accommodate various formulation variables. In this work, when the particle size equals the microdomain size, a symmetry-broken phase appears in a narrow range of particle sizes and compositions, which we named the "train track" structure. In this phase, the NPs aligned into a 3-D hexagonal lattice and packed asymmetrically along the c axis, making the projection of the ac and the bc plane resemble train tracks. Computational studies show that the broken symmetry reduces the polymer chain deformation and stabilizes the metastable hexagonally perforated lamellar morphology. Given the mobility of the multicomponent blend, the system shows a self-sorting behavior: segregating into two macroscopic phases with different nanostructures based on only a few nanometers NP size differences. Smaller NPs form "train track" morphology, while larger NPs form a "simple hexagon" structure, where the NPs take a symmetric hexagonal arrangement. Detailed structural evolution and simulation studies confirm the systematic-wide cooperativity across different components, indicating the strong self-regulation of the multicomponent system.
"train track" morphology↗
Development of Self-Assembly Supports Enabling Transformational Membrane Performance for Cost-Effective Carbon Capture
This final technical report describes work conducted by Membrane Technology and Research, Inc. (MTR) for the U.S. Department of Energy (DOE), National Energy Technology Lab (NETL) on the development of membranes with transformational performance for carbon capture under award number DE-FE0031596. The work was performed from June 1, 2018 through May 31, 2024. For more than a decade, MTR has worked in partnership with DOE to develop an innovative membrane-based CO 2 capture process. This effort has included the first test of membrane modules with coal-fired flue gas at the Arizona Public Services (APS) Cholla plant in 2010; the accumulation of >11,000 hours of flue gas operation for Polaris modules on a bench-scale 1 tonne/day (TPD) system at the National Carbon Capture Center (NCCC); scale-up of first-generation (Gen-1) Polaris to a 20 TPD small pilot system, and successful operation of this system on a flue gas slipstream at NCCC and in integrated boiler testing at Babcock & Wilcox (B&W). Through continued development efforts, a second-generation (Gen-2) version of the Polaris membrane has been scaled-up to pilot production. This membrane offers 70% higher CO 2 permeance with similar selectivity to the base case Polaris. MTR also developed planar modules designed specifically for the low-pressure, high-volumetric flow rate process conditions of flue gas operation. These new modules have significantly lower pressure-drop values compared to the type originally used (spiral-wound modules), which results in significant energy savings. The goal of the work described in this report was to improve on the Polaris Gen-2 membrane with the ultimate aim to reduce the cost of carbon capture. The majority of the effort was to develop improved support membranes for the multi-layer composite structure of MTR’s Polaris membrane. Earlier work at MTR had identified the support structure as limiting membrane permeances, not because the support itself represents a permeation resistance, but because the distribution of pores at the surface of the support imposes a geometric restriction to diffusion in the layers above it. Support membranes were prepared from a range of polymers, including commercially available block copolymers and a custom synthesized block copolymer alternative. The best support membranes developed in this project reduced the geometric restriction by a factor of two to three. These supports then were used to produce Polaris composite membranes with improved permeances. The second topic was to create a high-selectivity version of the Polaris membrane. The high-selectivity version uses a novel selective polymeric material and high selectivities were confirmed in experiments at MTR. The material is not easily made into very thin films. Consequently, the permeances are significantly lower than the Polaris Gen-2 membrane. The utility of this membrane is therefore limited to the carbon dioxide purification step that produces liquid CO 2 . A Technical and Economic Analysis (TEA) was performed for a carbon capture system that uses both advanced membrane types. The TEA shows the novel advanced membranes reduce the cost of capture by 10%, from $63.32/tonne CO 2 to $56.90/tonne CO 2 (2022 USD). Most of the development work was carried out with laboratory-scale casting and coating equipment. A number, but not all, of the improvements identified have been implemented on commercial-scale manufacturing equipment. The focus of future work at MTR is to incorporate the advancements made into the Polaris membrane manufacturing process.
01 COAL, LIGNITE, AND PEAT↗
Direct Observation of Micelle Fragmentation via In Situ Liquid-Phase Transmission Electron Microscopy
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99 GENERAL AND MISCELLANEOUS↗
Exceptionally Fast Ion Diffusion in Block Copolymer-Based Porous Carbon Fibers
Confined ionic liquids in hydrophilic porous media have disrupted lattices and can be divided into two layers: An immobile ion layer adheres to the pore surfaces, and an inner layer exhibits faster mobility than the bulk. In this work, we report the first study of ionic liquids confined in block copolymer-based porous carbon fibers (PCFs) synthesized from polyacrylonitrile-block-polymethyl methacrylate (PAN-b-PMMA). The PCFs contain a network of unimodal mesopores of 13.6 nm in diameter and contain more hydrophilic surface functional groups than previously studied porous carbon. Elastic neutron scattering shows no freezing point for 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF 4 ) confined in PCFs down to 20 K. Quasi-elastic neutron scattering (QENS) is used to measure the diffusion of [BMIM]BF 4 confined in PCFs, which, surprisingly, is 7-fold faster than in the bulk. The unprecedentedly high ion diffusion remarks that PCFs hold exceptional potential for use in electrochemical catalysis, energy conversion, and storage.
36 MATERIALS SCIENCE↗
Polymer infiltration synthesis of inorganic nanoporous coatings: Does polymer template affect their properties?
Synthesis of all-inorganic metal oxide architectures using polymer templates offers control over their thickness, porosity, and composition. Here, in this study, we provide insights into the synthesis of nanoporous zinc oxide films as a model system via infiltration of polymers that have different mechanisms of interaction with metal oxide precursors such as a polymer of intrinsic microporosity (PIM-1) and representative of the block-copolymers family (polystyrene-polyvinyl pyridine block copolymer). We investigated polymer infiltration process with both gas (diethyl zinc, DEZ, and water vapors) and solution (zinc acetylacetonate, Zn(acac) 2 , dissolved in ethanol) phase precursors. Using quartz crystal microbalance (QCM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses, we systematically studied the effect of polymer template and the form of the metal oxide precursors on the properties of synthesized metal oxide thin coatings. We demonstrate that the infiltration of polymer templates can be efficiently achieved using both gas phase and solution phase precursors. We show that the crystallinity of the synthesized 200 nm ZnO films is mainly affected by the state of the precursor (gas or solution phase) and does not depend on the polymer template type. In turn, the polymer type affects the surface termination of ZnO films. We demonstrate that the surface of porous ZnO coatings synthesized with BCP (here PS-P4VP) is more accessible than the surface of ZnO synthesized with PIM; however, despite the lower surface accessibility for ethanol molecules, ZnO synthesized via infiltration of PIM-1 with solution-phase precursors demonstrates the largest change in resistivity upon its exposure to ethanol vapor at room temperature.
36 MATERIALS SCIENCE↗
How Do Ionic Liquids “Fold” Ionenes? Computational and Experimental Analysis of Imidazolium Polymers Based on Ether and Alkyl Chain Variations Dissolved in an Ionic Liquid
Molecular dynamics (MD) simulations and complementary experiments are used here to understand the inter- and intramolecular structure and conformational properties of ionenes (i.e., cationic polymers formed from condensation reactions) dissolved in an ionic liquid (IL), 1-ethyl-3-methylimidazolium bistriflimide [C 2 mim + ][Tf 2 N - ]. The simulated structural properties are benchmarked against experimental analyses of these same polymers, mainly using dynamic light scattering (DLS) experiments. Four different imidazolium ionenes are considered, corresponding to variations in the chemistry and structure of the repeat units including: (1) poly (decylimidazolium) (PD 10 ); (2) poly (tetraethyleneglycolimidazolium) (PE 10 ); (3) alternating copolymer (P(ED) 5 ); and (4) a block copolymer (PE 5 D 5 ). Detailed computational analyses of the polymer structure and conformational properties were performed, including the radius of gyration, end-to-end distance, torsional distributions, and site-site and spatial distribution functions. Overall, there is a competition between intramolecular associations between the imidazolium groups and the ether sites in the polymers versus the intermolecular interactions of the polymer imidazolium groups with the surrounding anion molecules. The polymer with only ether linkages (PE 10 ) results in the most intramolecular interactions, leading to significant coiling behavior and chain contraction. These strong interactions reduce chain flexibility, but they also result in much more linear chain configurations and alignment of the imidazolium groups. The polymer structure is strongly affected as the concentration of alkyl groups is increased, and we find that the polymer architecture (alternating versus block copolymer) also has an important influence. Furthermore, these detailed observations are important for understanding the connection between the molecular design of imidazolium polymers and their emergent structural properties, which could lead to unique opportunities for creating polymer composites.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Improved Self-Assembly of P3HT with Pyrene-Functionalized Methacrylates
A block copolymer with discotic liquid crystalline behavior was synthesized using Grignard metathesis polymerization (GRIM) and initiators for continuous activator regeneration atom transfer radical polymerization (ICAR-ATRP). A novel discotic liquid crystalline mesogen, 6-(pyren-1-yloxy)hexyl methacrylate (PyMA), comprises a block that is attached to regioregular poly(3- hexylthiophene) (rr-P 3 HT) generated by GRIM and subjected to end-group modification. Due to the continuous regeneration of Cu + in the reaction mixture in ICAR-ATRP compared to conventional methods, the synthesis was successfully performed with less catalyst. The purity and yield of the final product are increased by eliminating rigorous post-synthesis purification. Stacked pyrene units have contributed to the enhanced long-range π-π interactions and aligning of the P 3 HT block as observed in thin-film X-ray diffraction (XRD). Furthermore, field-effect mobilities in the order of 10 -2 cm 2 V -1 s -1 in bottom-gate, top-contact organic field-effect transistors (OFETs) suggest an enhancement in charge transport due to the discotic electron-rich pyrene units that help mitigate the insulating effect of the methacrylate backbone. The formation of uniform microdomains of P 3 HT-bpoly(PyMA) observed with tapping mode atomic force microscopy (TMAFM) on the channel regions of OFETs indicates the unique packing of the block copolymer in comparison to pristine P 3 HT. Thermotropic properties of the novel discotic mesogen in the presence and absence of P3HT were observed with both the poly(3-hexylthiophene)-b-poly(6-(pyren-1-yloxy)hexyl methacrylate) (P3HT-b-poly(PyMA)) block copolymer and poly(6-(pyren-1-yloxy)hexyl methacrylate) (poly(PyMA)) homopolymer using polarized optical microscopy (POM) and differential scanning calorimetry (DSC).
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Structure and Shape of Surface-Mediated Assembly of Surfactants
Achieving controls on the self-assembly of cationic and block copolymer micelles has significant implications for advancing novel material systems for energy, environmental, and biological applications and for tuning fluid flow behavior in subsurface geologic environments. While it is known that the aggregation of micelles is influenced by the composition of the surrounding fluid, the influence of a solid interface has been less explored. In this study, we probe the organization of cetyltrimethylammonium bromide (CTAB) micelles in the absence and presence of the Pluronic P123 block copolymer and quartz substrate using transmission and grazing-incidence small-angle X-ray scattering measurements and classical molecular dynamics (MD) simulations. In the absence of the quartz interface, CTAB with and without P123 molecules assemble as ellipsoid core–shell micelles. Densification of the core on adding P123 is noted from the decrease in the core radius from 15.9 to 14.6 Å. Here, the presence of a quartz substrate causes the micelles to elongate, which is noted by the emergence of a power-law slope in the low q region (<0.02 Å –1 ). Moreover, in the presence of both P123 and the quartz substrate, the micelle shape changes from ellipsoid core–shell to cylindrical core–shell, and a significantly higher number of aggregates are formed. The higher number of aggregates, and faster aggregation kinetics are linked to the organization of the solvent structures as noted from the MD simulations. These findings demonstrate the effects of adding a block copolymer and including a quartz substrate on the self-assembly of cationic (CTAB) micelles, which can be used to inform the design of functional material systems that harness surfactant chemistries.
42 ENGINEERING↗
Deciphering the Olefin Isomerization-Polymerization Paradox of Palladium(II) Diimine Catalysts: Discovery of Simultaneous and Independent Pathways of Olefin Isomerization and Living Polymerization
This work elucidates a long-standing unexplained paradox commonly observed within the polymerization of α-olefin using palladium (Pd)(II)–diimine catalysts, in which isomerization and living polymerization of α-olefins are both observed. With a classical mechanistic understanding of these complexes, this behavior is often dismissed and interpreted as experimental error. Herein, we present a comprehensive mechanistic investigation into this phenomenon that supports the existence of a novel mechanistic pathway for Pd(II)–diimine complexes. Part one of the mechanistic study lays the foundation of the proposed mechanism, in which neutral Pd(II)–diimine complexes were found to exhibit a moderate to good catalytic activity for olefin isomerization of α-olefins despite the established notion that catalyst activation is required. Extensive experimental and computational studies reveal the possibility of a partial dissociation of the diimine ligand, which frees up one coordination site and enables coordination–insertion. This finding is significant as the coexistence of two reactive coordination sites at the palladium center becomes a valid proposal for the activated cationic Pd(II)–diimine complexes. In part two, we examined and validated the simultaneously observed α-olefin isomerization and living polymerization using the cationic Pd(II)–diimine catalyst, which supports the presence of two independent reaction pathways of isomerization and polymerization, respectively. Furthermore, the addition of a strong Lewis acid, such as AlCl 3 , accelerates the ligand dissociation and the consequential isomerization as it weakens the palladium–nitrogen bond through competitive binding. In part three, Lewis acid-triggered olefin isomerization-polymerization is employed to prepare living olefinic block copolymers and further synthesize novel polyolefin-polar block copolymers with unique architectures, distinct levels of branching, crystallinity, and polar functionality in a one-pot manner.
Catalysts↗
Status and Targets for Polymer-Based Solid-State Batteries for Electric Vehicle Applications
There is growing interest in the development of Li-metal-based solid state batteries, driven by their promise in improving the energy density to satisfy electric vehicle requirements. In this work, we examine the status of Solid polymer electrolytes (SPEs) based solid state batteries for electric vehicle applications using a continuum scale mathematical model. We examine LiFePO4(LFP) cathode/lithium metal anode batteries containing three different electrolytes, namely (1) a liquid electrolyte, (2) the polystyrene-b-poly(ethylene oxide) (SEO) block copolymer electrolyte, and (3) a single-ion conducting (SIC) block copolymer electrolyte, with the liquid electrolyte serving as the baseline for the comparison. By using an optimization procedure, we assemble "virtual" batteries to identify the optimal design that maximizes energy density while allowing the power requirements of electric vehicles (EVs) to be satisfied. Results show the present status of different SPEs are still below what is considered acceptable and further improvements are needed to achieve electric vehicle targets. The optimization studies conducted here show that for low transference number electrolytes (similar to 0.2) the conductivity target is 5 x 10(-3)S cm(-1), while for a unity transference number electrolyte this target decreases to 4 x 10(-4)S cm(-1). These targets provide guidance for polymer synthesis researchers to develop better polymers for use in EVs.
25 ENERGY STORAGE↗
Self-assembled elastomers with molecularly encoded tissue-like softness, strain-adaptive stiffening and coloration
The invention generally relates to linear-bottlebrush-linear copolymer blocks and methods of making and using same. The disclosed copolymer blocks can be useful in, for example, the formation of polymer networks that replicate biological stress-strain behavior. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present invention.
Sheiko, Sergei↗
Crystalline Imide/Arylene Ether Copolymers
Series of imide/arylene ether block copolymers prepared by using arylene ether blocks to impart low melt viscosity, and imide blocks to provide high strength and other desirable mechanical properties. Work represents extension of LAR-14159 on imide/arylene ether copolymers in form of films, moldings, adhesives, and composite matrices. Copolymers potentially useful in variety of high-temperature aerospace and microelectronic applications.
Jensen, Brian J.↗
Functional and Multifunctional Polymers: Materials for Smart Structures
The ultimate goal of the research in smart structures and smart materials is the development of a new generation of products/devices which will perform better than products/devices built from passive materials. There are a few examples of multilayer polymer systems which function as smart structures, e.g. a synthetic muscle which is a multilayer assembly of a poly(ethylene) layer, a gold layer, and a poly(pyrrole) layer immersed in a liquid electrolyte. Oxidation and reductions of the active pyrrole layer causes the assembly to reversibly deflect and mimic biological muscles. The drawback of such a setup is slow response times and the use of a liquid electrolyte. We have developed multifunctional polymers which will eliminate the use of a liquid electrolyte, and also because the functionalities of the polymers are within a few hundred angstroms, an improved response time to changes in the external field should be possible. Such multifunctional polymers may be classified as the futuristic 'smart materials.' These materials are composed of a number of different functionalities which work in a synergistic fashion to function as a device. The device performs on the application of an external field and such multifunctional polymers may be scientifically labeled as 'field responsive polymers.' Our group has undertaken a systematic approach to develop functional and multifunctional polymers capable of functioning as field responsive polymers. Our approach utilizes multicomponent polymer systems (block copolymers and graft copolymers), the strategy involves the preparation of block or graft copolymers where the functionalities are limited to different phases in a microphase separated system. Depending on the weight (or volume) fractions of each of the components, different microstructures are possible. And, because of the intimate contact between the functional components, an increase in the synergism between the functionalities may be observed. In this presentation, three examples of multifunctional polymers developed in our labs will be reported. The first class of multifunctional polymers are the microphase separated mixed (ionic and electronic) conducting or MIEC block copolymers. The second class being developed in our labs are the biocompatible conductive materials and the conductive fluids. The final class may be considered microwave active smart polymers.
Arnold, S.↗