Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session B70: Polymer Dynamics at the Nano-to Meso-Scale Revealed by X-ray and Neutron Spectroscopy IIFocus
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Sponsoring Units: DPOLY DSOFT Chair: Tad Koga, State Univ of NY - Stony Brook Room: 208 |
Monday, March 2, 2020 11:15AM - 11:27AM |
B70.00001: Soft Matter Dynamics with Neutron Spin Echo Spectroscopy at the Spallation Neutron Source Piotr Zolnierczuk, Laura-Roxana Stingaciu, Michael Monkenbusch
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Monday, March 2, 2020 11:27AM - 11:39AM |
B70.00002: Dynamics of multi-domain macro-molecules in the context of polymer physics Laura-Roxana Stingaciu, Volker Urban Conformational ensembles of synthetic polymers and intrinsic disorder in proteins are both aspects of the varying degree of order and disorder that are crucial for the properties of macro-molecules. Neutron scattering techniques, in particular small angle scattering and neutron spin echo, have an important contributions to understand conformation and dynamics of macro-molecules with regards to polymer physics. The possibility for altering and defining accessible conformational spaces through localized or intermediate and long-range interactions of segments along a polypeptide chain are limited by chain stiffness and local hydrodynamic friction. Our research aims for a deeper understanding of this challenging topic. We will present the dynamics of several bio-molecular species based on results of neutron scattering and the comparison with secondary and segmental relaxations, Rouse and reptation dynamics in polymers, with emphasis on the significant difference between dynamics of random coil of synthetic polymers and the dynamics of globular proteins. |
Monday, March 2, 2020 11:39AM - 11:51AM |
B70.00003: WITHDRAWN ABSTRACT
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Monday, March 2, 2020 11:51AM - 12:03PM |
B70.00004: Length-Scale Dependence of Block Copolymer Segmental Dynamics Daniel Hallinan, Oluwagbenga Iyiola, Kunlun Hong, Monojoy Goswami, Piotr Zolnierczuk, Laura-Roxana Stingaciu, William Thomas Heller, Kyoungmin Kim This work examines the effect of interface proximity and tethering on polymer segmental motion. Selectively deuterated block copolymers (BCPs) were studied with neutron spin echo (NSE) spectroscopy. A strongly segregated BCP was used as a model system in which a glassy deuterated polystyrene (dPS) block acted as the interface and the dynamics of a rubbery deuterated polyethylene oxide (dPEO) block was studied. The PEO block was selectively protonated as a label to examine the dynamics near the interface in one sample and near the chain end in another sample. A strong slowing of segmental dynamics in the sample with the protonated label tethered directly to the dPS was observed compared to the dynamics of the sample with the protonated label at the chain end, but with an unexpected length scale dependence. The slowing was only observed at length scales significantly larger than the characteristic PEO segment length (1 nm), and the disparity between interfacial and chain-end dynamics grew with increasing length. The novelty of examining polymer chain motion over a wide range of length scales is enabled by NSE of selectively deuterated BCPs and can impact BCP applications including batteries, water treatment, and gas separations. |
Monday, March 2, 2020 12:03PM - 12:15PM |
B70.00005: Investigating the effect of salt on polymer dynamics in block copolymer electrolytes through neutron spin-echo spectroscopy Whitney Loo, Antonio Faraone, Nitash Balsara Block copolymers have been studied for use in lithium metal solid-state batteries due to their ability to decouple ion transport and mechanical properties. While it is well known that the salt preferentially segregates into the conducting block, and that the motion of salt molecules is coupled to that of the polymer segments that solvate the ions, many questions about the nature of this coupling remain unanswered. Neutron spin-echo spectroscopy experiments were used to elucidate the nature of this coupling; the sample used was a mixture of a protonated and deuterated polystyrene-b-poly(ethylene oxide) doped with a lithium salt. The isotopic labeling allowed for only the dynamics of the ion-containing block, poly(ethylene oxide), to be measured. We quantified the dynamics, corresponding to length scales of about 5 nm, by comparing the data to predictions based on the Rouse model at low times as well as the standard tube model at long times. The crossover time between these modes was determined as a function of salt concentration. The tube shrinks with added salt and the segments slow down due to this. There is a direct relationship between segmental dynamics measured on the monomer length scale and ion transport under an applied field on macroscopic length scales. |
Monday, March 2, 2020 12:15PM - 12:27PM |
B70.00006: Ion transport in solid polymeric lithium ion electrolytes Hans-Georg Steinrueck, Christopher Takacs, David Mackanic, Benjamin Holladay, Hong Keun Kim, Chuntian Cao, Suresh Narayanan, Eric Dufresne, Yuriy Chushkin, Federico Zontone, Beatrice Ruta, Johannes Will, Oleg Borodin, Sunil K Sinha, Venkat Srinivasan, Michael Toney Understanding ion transport in solid polymeric electrolytes (SPEs) continues to be of interest concerning improving safety and energy density of lithium-ion batteries. Towards this end, we present an investigation of lithium ion transport in a baseline SPE consisting of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in Poly(ethylene oxide) (PEO) via a combination of x-ray photon correlation spectroscopy (XPCS), x-ray absorption microscopy (XAM), continuum modelling, and molecular dynamics (MD) simulations. |
Monday, March 2, 2020 12:27PM - 12:39PM |
B70.00007: Diffusion of Lithium Salt in Block Copolymer Kyoungmin Kim, Micah Silverman, Daniel Hallinan Salt-doped polymer electrolytes can replace the flammable liquid electrolytes enhancing safety and chemical stability. The challenges to apply the polymer electrolytes to commercial batteries are dendrite formation and the low ionic conductivity. Understanding the ionic transport is essential to design high-performance batteries. Limitations of the conventional electrochemical measurements arise as the system gets complicated. Accurate and straightforward way to measure the transport properties is required. We successfully applied the measurement technique using time-resolved Fourier Transform infrared - attenuated total reflectance (FTIR-ATR) spectroscopy to polymer electrolytes. The diffusion coefficients of lithium salt through a polystyrene-poly(ethylene oxide) block copolymer (SEO) electrolytes were investigated. Since the concentration gradient is the only driving force, the diffusion coefficient could be decoupled with the ionic conductivity and transference number. The results showed non-monotonic dependence of the diffusion coefficient on the salt concentration implying the polymer structure or ion dissociation plays a role in the diffusion in concentrated polymer electrolyte. |
Monday, March 2, 2020 12:39PM - 12:51PM |
B70.00008: Unravelling the Interplay Between Structural Dynamics and Water Transport in Perfluorosulfonated Ionomer Nanocomposites Through the use of Neutron Scattering and Infrared Spectroscopy Apoorva Balwani, Allison B Domhoff, Madhusudan Tyagi, Antonio Faraone, Eric M Davis Ionomer nanocomposites are attractive as proton exchange membranes in redox flow batteries, as they combine the thermo-chemical resistance of perfluorosulfonated ionomers with the reduced vanadium ion transport due to the presence of silica nanoparticles (SiNPs). However, elucidating the impact of SiNPs on the structural ordering and transport properties of these nanocomposites is an ongoing challenge. In this study, neutron spin echo (NSE) spectroscopy and high flux backscattering (HFBS) spectroscopy were employed to probe changes in polymer segmental dynamics and water dynamics, respectively, while small-angle neutron scattering (SANS) was used to investigate the SiNP dispersion state. In tandem with these techniques, infrared spectroscopy was used to capture water transport and water-induced swelling of the ionomer nanocomposites. Data from this complementary set of techniques indicate that SiNPs inhibit both viscoelastic relaxations and segmental dynamics of the ionomer network. Further, ionomer swelling and water transport in these nanocomposites were found to be highly coupled, leading to a complex water transport mechanism in these membranes. Finally, SiNP surface chemistry was established as a handle for tunability for ionic transport in perfluorosulfonated ionomers. |
Monday, March 2, 2020 12:51PM - 1:03PM |
B70.00009: WITHDRAWN ABSTRACT
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Monday, March 2, 2020 1:03PM - 1:15PM |
B70.00010: Structure and dynamics of homogeneously and heterogeneously crosslinked PNIPAM microgels Tetyana Kyrey, Judith Witte, Laura-Roxana Stingaciu, Marcus Witt, Regine von Klitzing, Stefan Wellert, Olaf Holderer Thermoresponsive poly(N-isopropylacrylamide) microgel particles have been largely studied in the past due to their interesting fundamental properties as well as their potential for application in drug delivery, sensor technology or biotechnology. In this contribution, microgel particles with homogeneous and heterogeneous crosslink distribution and different crosslinker concentrations will be studied with small angle neutron scattering (SANS) and neutron spin echo spectroscopy (NSE). |
Monday, March 2, 2020 1:15PM - 1:27PM |
B70.00011: Dynamics of polymeric additives in bicontinuous microemulsions adjacent to planar hydrophilic surfaces Henrich Frielinghaus, Frederik Lipfert, Olaf Holderer, Stefan Mattauch, Michael Monkenbusch, Nikolas Arend, Dieter Oswald Richter Close to a planar surface, lamellar structures are imposed upon otherwise bulk bicontinuous microemulsions. Thermally induced membrane undulations are modified by the presence of the rigid interface. While it has been shown that pure membrane dynamics are accelerated close to the interface, we observed nearly unchanged relaxation rates for membranes spiked with large amphiphilic diblock copolymers with respect to the bulk. An increase of the polymer concentration by a factor of 2–3 for the first and second surfactant membrane layers was observed. We interpret the reduced relaxation times as the result of an interplay between the bending rigidity and the characteristic distance of the first surfactant membrane to the rigid interface, which causes the hydrodynamic and steric interface effects described in Seifert’s theory. The influence of these effects on decorated membranes yields a reduction of the frequencies and an amplification of the amplitudes of long-wavelength undulations, which are in accordance to our experimental findings. |
Monday, March 2, 2020 1:27PM - 1:39PM |
B70.00012: High shear rate rheology in microcapillary flow with SANS Paul Salipante, Ryan Murphy, Vishnu Dharmaraj, Katie Weigandt, Steven Hudson The rheology of shear-banding wormlike micelle solutions, which exhibit polymeric viscoelasticity, is investigated at high shear rates using capillary rheometry, particle-streak velocimetry, and small-angle neutron scattering (SANS). The capillary entrance flow was examined so that results of fully developed flow are reported. Such results show shear-thinning power-law behavior for all channel geometries from shear rates of 1,000 /s to nearly 1,000,000 /s. Two distinct power-law behaviors with increasing shear rate indicate a structural change with corresponding broadening of neutron scattering. The transition between these two power laws shifts with changing surfactant concentration and temperature. |
Monday, March 2, 2020 1:39PM - 2:15PM |
B70.00013: In-Situ/Operando X-ray Photon Correlation Spectroscopy Studies of Polymer Dynamics During 3D-Printing of Dual-Cure Polymer Epoxy Invited Speaker: Stanislas Petrash Synchrotron-based X-ray Photon Correlation Spectroscopy (XPCS) was used to probe the dynamic properties of soft matter at relevant size (submicrons) and time-scales (milliseconds). We combined XPCS with in-operando capabilities of synchrotron beamlines to shed light onto the unexplored dynamics of dual-cure (UV/thermal) industrial polymers for advanced 3D printing applications. We studied, in operando: a) the structural evolution and corresponding dynamics of the polymer during the extrusion phase of 3D printing, b) anisotropic structure formation & interfacial behavior during subsequent settling and UV curing, and c) the process of final thermal cure. The results revealed a) anisotropic polymer dynamics in different directions (printing (horizontal) vs. extrusion (vertical)) during printing and settling of the material, b) two-stage crosslinking dynamics during UV curing, and c) the chain dynamics near the polymer-polymer interface between 3D-printed filaments as a function of the distance from the interface. The present study shows that an in-situ/ operando XPCS is not only an excellent technique for comprehensive, quantitative characterization of 3D printing processes, but also provides an unprecedented opportunity to perform studies of a wide variety of nonequilibrium phenomena of polymeric materials under external stimuli. |
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