Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session F42: Polymer Physics PrizeInvited Live Streamed Prize/Award
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Sponsoring Units: DPOLY Chair: Arun Yethiraj Room: McCormick Place W-375A |
Tuesday, March 15, 2022 8:00AM - 8:36AM |
F42.00001: Polymer Physics Prize (2022): Controlling Nanoparticle Ordering by Directional Polymer Crystallization Invited Speaker: Sanat K Kumar We have previously shown that nanoparticles (NPs), which are initially miscible with a polymer melt, can be ordered by polymer crystallization. The key variable here is a Peclet number (Pe) that compares the time scale of NP motion to the rate of polymer crystallization. For large Pe the NPs are frozen in place during polymer crystallization. However, for Pe values less than 1 the NPs are moved by the growing crystals and selectively placed in the interlamellar, interfibrillar and interspherulitic regions. These results are in line with the Keith and Padden’s findings, expanded on by Russell et al., on the spatial dispersion of amorphous polymer defects in a semicrystalline morphology. The resulting samples have Young’s moduli that are increased by a factor of ~2 relative to ones where the NPs are randomly ordered. |
Tuesday, March 15, 2022 8:36AM - 9:12AM |
F42.00002: Design of Polymer Electrolytes with Superionic Ion Transport Invited Speaker: Rachel A Segalman Progress toward durable, high-energy density lithium-ion batteries has been hindered by instabilities at electrolyte-electrode interfaces leading to poor cycling stability, and by safety concerns associated with energy-dense lithium metal anodes. Solid polymeric electrolytes (SPEs) can help mitigate these issues, however SPE conductivity is limited by sluggish polymer segmental dynamics. Transport through the free volume of ordered, superionically conductive domains results in decoupling of ion motion and polymer segmental dynamics. Although crystalline domains are conventionally detrimental to ion conduction in SPEs, we demonstrate that semicrystalline polymer electrolytes with labile ion-ion interactions and tailored ion sizes exhibit excellent lithium conductivity (1.6 mS/cm) and selectivity (t+~0.6-0.8). This allows for simultaneous optimization of typically orthogonal properties including conductivity, Li-selectivity, mechanics, and processability. |
Tuesday, March 15, 2022 9:12AM - 9:48AM |
F42.00003: Entropic Freezing of Diffusion of Macromolecules at Intermediate Confinements Invited Speaker: Murugappan Muthukumar Our recent discovery [1-3] of the non-diffusive Topologically Frustrated Dynamical State (TFDS) in polymer dynamics will be annotated with its essential features. It is well known that the Zimm-Rouse (Ogston) model, entropic barrier model, and reptation model, respectively, adequately describe the diffusion of macromolecules as the degree of confinement by their environment is progressively increased. As a remarkable departure, for intermediate degrees of confinement preceding the entangled regime, macromolecules do not diffuse even though the experimental conditions are at room temperature, which is a drastic deviation from the Einstein law of diffusion valid at all non-zero temperatures. The origin of TFDS is attributed to extreme metastability arising from cooperative action of multiple deep entropic traps on a single confined macromolecule. We will discuss the magnitude of the extreme metastability in terms of its effective entropic barrier preventing its diffusion, transition from TFDS into entanglement regime, and implications of the TFDS. |
Tuesday, March 15, 2022 9:48AM - 10:24AM |
F42.00004: Dynamics and Solvation of Ionic Liquids with Polymer-Grafted Nanoparticles Invited Speaker: Pinar Akcora Dispersion and self-assembly of polymer-grafted nanoparticles have been utilized for diverse applications requiring enhanced thermo-mechanical properties of polymer nanocomposites and solute transport and ion binding in thin films. One example of grafted particles in solution is the use of weak polyelectrolyte grafts which can form networks through hydrogen bondings. Our group works on designing polymer-grafted magnetic nanoparticles as active electrolytes where the chains interact with electrolytic media of ionic liquids. I will present two different systems with nonionic and ionic grafted chains and discuss the effect of ion-dipole and ionic interactions between polymer chains and ionic liquids on the conductivity and dynamic properties of ionic liquids. Anions and cations pertaining to the ionic liquid preferentially interact with the methyl groups of poly(methyl methacrylate) and with the sulfonated groups of poly(styrene sulfonate), respectively. These interactions can be used to mitigate the whole ionic conductivity and the free mobile counterion distribution in the copolymer-grafted nanoparticle-based electrolyte membranes. Adding solvent into grafted particle/ionic liquid mixtures enhances the conductivity of the system, suggesting that chain swelling influences the solvation of the ionic liquid. These findings showcase the importance of polymer-coupled dynamics and solvation of ionic liquids in hybrid electrolytes. |
Tuesday, March 15, 2022 10:24AM - 11:00AM |
F42.00005: Polymer Grafted Nanoparticles for Materials Design Invited Speaker: Brian C Benicewicz Over the past 15 years, the application of controlled radical polymerization techniques to grafted polymer chains has enhanced our ability to design the critical interface between inorganic particles and polymer matrices. These interfaces can be prepared with control over many molecular variables such as chain density, chain length, polydispersity, chain architecture (e.g., block, gradient), end group chemistry, etc. In addition, interfaces can be created to contain multiple functionalities. We have used the RAFT (reversible addition-fragmentation chain transfer) polymerization method with polymer grafting techniques as an approach to modify the surfaces of nanoparticles with a variety of functional polymers. We developed multiple approaches for attaching RAFT agents to the surface of nanoparticles with graft densities ranging from 0.01 to 0.8 chains/nm2. Using these surface-immobilized RAFT agents, many monomers can be polymerized on the nanoparticle surfaces via surface-initiated RAFT polymerization in a controlled manner. However, this diversity of design strategies is not limited to a single population of chains. Another set of RAFT agents can be attached to the remaining free surface and a second (or third) population of polymer chains can be polymerized from the surface of the same particles. This subsequent set of chains can possess a completely independent set of molecular variables (chain density, molecular weight, chemistry, architecture, etc.) from the initial population of grafted chains. Thus, an almost limitless design space is available to create highly specified interfaces on nanoparticles. This presentation will provide an overview of the chemistry used to prepare multimodal polymer-grafted nanoparticles with precise control over multiple polymer chain variables, and examples in select applications. |
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