Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session F15: Rheology and Mechanics of PolymersFocus
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Sponsoring Units: DPOLY Chair: Konane Bay, Princeton University Room: Room 207 |
Tuesday, March 7, 2023 8:00AM - 8:36AM |
F15.00001: Break
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Tuesday, March 7, 2023 8:36AM - 8:48AM |
F15.00002: Experimental Test of Heterogeneous Rouse Model for the Origin of Time-Temperature Superposition Breakdown near the glass transition Peijing Yue, David S Simmons Time-Temperature Superposition (TTS) has been widely employed in analyzing dynamic and mechanical data. However, beginning with Plazek in the 1960's, data has been reported showing a breakdown of TTS near the glass transition. For example, rheological data on polystyrene show clear evidence of TTS breakdown between 105? and 130 ?. This breakdown takes the form of a decoupling of polymer chain and segmental dynamics. Our group recently proposed a Heterogeneous Rouse Model (HRM) that explains this effect based on the presence of a distribution of relaxation times. Here, we report on extensions of this model to predict multiple linear-regime rheological properties such as complex modulus and creep, and we compare these predictions to new experimental data combining dielectric spectroscopy and rheological measurements. |
Tuesday, March 7, 2023 8:48AM - 9:00AM |
F15.00003: Extensional viscosity of associative polymers and their mixtures with spherical polymer micelles Eugene Pashkovski Associative polymers were prepared by modifying the olefin copolymer (OCP) backbone with a small mole fraction of polar groups (stickers). Self-assembled ~30-nm spherical polymer micelles (SPM) contained polymethyl methacrylate (PMMA) core stabilized with poly(lauryl)methacrylate corona.? Extensional viscosity of dilute solutions of associative oil-soluble polymers was investigated using Capillary Breakup Extensional Rheometer (CaBER).?Using the analysis of elasto capillary (EC) thinning, we show that the molecular extensibility of associative polymers decreases as compared for the non-associative OCP with the same molecular weight. However, in the presence of SPM, the extensional viscosity and relaxation time for dilute polymer solutions increase quite significantly.? Possible mechanisms of this effect are discussed in terms of finite extensibility non-linear elastic (FENE) dumbbell model. |
Tuesday, March 7, 2023 9:00AM - 9:12AM |
F15.00004: Dynamics of Associative Polymers with High Density of Reversible Bonds Myoeum Kim, Shifeng Nian, Shalin Patil, Siteng Zhang, Quan Chen, Mikhail Zhernenkov, Ting Ge, Shiwang Cheng, Liheng Cai For more than 30 years, the understanding of associative polymers is that reversible bonds change the shape of linear viscoelastic spectra by adding a plateau in the intermediate frequency range, at which reversible bonds have not yet relaxed and act as crosslinks. We show this molecular picture is incorrect for homogenous associative polymers carrying high density of stickers. Our discovery is explained by a renormalized Rouse model that highlights an unexpected influence of reversible bonds on the structural relaxation rather than the shape of viscoelastic spectra of associative polymers. |
Tuesday, March 7, 2023 9:12AM - 9:24AM |
F15.00005: Entanglements via Slip-Springs with Soft, Coarse-Grained Models for Systems Having Explicit Liquid-Vapor Interfaces Ludwig Schneider, Juan J De Pablo With advances in nano-rheology modelling entangled polymeric materials with their unique visco-elastic properties via computer simulations becomes important. |
Tuesday, March 7, 2023 9:24AM - 9:36AM |
F15.00006: Transition from collective to pairwise entanglements Danyang Chen, Liel Sapir, Michael Rubinstein Topological entanglements restrict the fluctuations of network strands and control the mechanical properties of high molecular weight polymer networks. Polymer entanglements have traditionally been modeled in two different ways, either using a collective mean-field confining potential that restricts fluctuations of network strands to confining tubes or by discrete pairwise interactions between chains. We discovered a connection between these two qualitatively different descriptions and proposed a method of obtaining affine length scale of deformed entanglement strand from the decay rate of the correlation function of bond vectors. Using this new method, we observed a cross-over from collective entanglements at weak network deformations to pairwise entanglements at strong deformations. |
Tuesday, March 7, 2023 9:36AM - 9:48AM |
F15.00007: Surface structure, mechanics and rheology of amphiphilic polymer conetworks on different length scales Kevin Hagmann, Nora Fribiczer, Sebastian Seiffert, Carolin Bunk, Frank Böhme, Regine von Klitzing In order to allow the simultaneous transport of hydrophilic and hydrophobic substances, networks with fine-structured hydrophilic and hydrophobic components are requested. Amphiphilic polymer co-networks (ACNs) can be tailored to create gels that selectively swell or collapse in different solvents with the corresponding polarity and greatly impact transport properties through these networks. |
Tuesday, March 7, 2023 9:48AM - 10:00AM |
F15.00008: Entanglement metric and percolation threshold in cellularized tangles under stretch Marco Pensalfini, Marino Arroyo Intermediate filaments (IFs) are a major class of cytoskeletal biopolymers, along with actin filaments (AFs) and microtubules (MTs). While AFs are widely recognized to largely control cell mechanics, it has been shown that IFs crucially contribute to the resilience of cell monolayers under severe stretch [Latorre et al, Nature, 2018]. AFs and MTs turnover quickly and form mechanically stable networks through crosslinking, whereas IFs are weakly crosslinked and turnover very slowly. Based on these features, we hypothesize that IFs can form stable tissue-wide networks thanks to physical entanglement. To examine this, we seek for a link between the degree of entanglement of a cellularized tangle, i.e. a set of open chains with the ends constrained to the enclosing cell boundaries, and the emergent mechanical response of the network under stretch. |
Tuesday, March 7, 2023 10:00AM - 10:12AM |
F15.00009: Motor-free contractility in light-controlled in-vitro protein networks Tuhin Chakrabortty, Xiangting Lei, Jerry E Honts, Saad Bhamla Contractile structures in the cytoskeleton are essential for various functions of living cells such as cell division and motility. Most of these structures utilize motor proteins for generating active contractility. However, recent experimental and theoretical studies have shown evidence and plausibility of motor-free contractile networks in the cytoskeleton. In this work, we are presenting a simple in-vitro motor-free model system capable of producing contractile structures. |
Tuesday, March 7, 2023 10:12AM - 10:24AM |
F15.00010: Coronavirus Peplomer Interaction Mona Kanso By virtue of their lack of motility, viruses rely entirely on their own temperature |
Tuesday, March 7, 2023 10:24AM - 10:36AM |
F15.00011: Connecting the Anomalous Rheology of Poly(2-vinylpyridine)/Octa(aminophenyl)silsesquioxane to Intermediate Polymer Relaxations Walter W Young, Reika Katsumata A molecular-level understanding of the rheology of polymer nanocomposite melts is critical for their use in high-throughput and advanced manufacturing techniques, but it is challenging due to the complex interplay between components and their geometry. To this end, polyhedral oligomeric silsesquioxane (POSS) provides an ideal platform for nanocomposite study because its extremely small size (~ 2 nm) makes the polymer matrix effectively "all-interfacial". In particular, such all-interfacial nanocomposites with attractive interactions (e.g., poly(2-vinylpyridine)/octa(aminophenyl) POSS: P2VP/OAPS) are known to reach ~ 50 vol% loading without OAPS aggregations. Recent works revealed that the significant increase in glass transition temperature in P2VP/OAPS could be explained well by the contributions of hydrogen bonds. However, there are unsolved questions regarding their anomalous rheological properties such as: 1) disappearance of entanglement plateau, 2) relatively small change in viscosity at high temperatures. This talk will share our recent systematic study of small amplitude oscillatory shear rheology with a wide range of molecular weights in P2VP/OAPS nanocomposites. We will explain the observed rheological behavior using the "slower process" of P2VP (relaxation mode between segmental and entire chain). The insights obtained in this study will be crucial to establishing property-processing rules for the next generation of nanocomposite materials. |
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