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 UU04: V: Advanced Polymer Phenomena |
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Sponsoring Units: DPOLY Chair: Sarah (Ying) Zhong, University of South Florida Room: Virtual Room 4 |
Wednesday, March 22, 2023 5:00AM - 5:12AM |
UU04.00001: Statistical Field Theory for Nonlinear Elasticity of Polymer Networks with Nonlocal Excluded Volume Interactions Pratik Khandagale, Timothy Breitzman, Carmel Majidi, Kaushik Dayal Existing phenomenological and micromechanical elastic models for rubbery polymers are unable to account for polymer molecular structure and inter-segment interactions. To address these limitations, we have developed a statistical mechanics-based field-theoretic model for polymer networks, which provides an efficient mesoscale approach that enables the accounting of excluded volume effects without the expense of large-scale molecular modeling. A mesoscale representative volume element is populated with multiple interacting chains, and the macroscale nonlinear elastic deformation is imposed by mapping the chain end-to-end vectors. |
Wednesday, March 22, 2023 5:12AM - 5:24AM |
UU04.00002: Bifurcation of Collapse Transition for Semiflexible Polymers Dilimulati Aierken, Michael Bachmann We extend our previous study [1] on a generic coarse-grained semiflexible polymer model with self-interactions and investigate the regime in the hyperphase diagram, parametrized by temperature and bending stiffness, where the known collapse transition bifurcates. For this purpose, we employ the recently developed generalized microcanonical inflection point analysis method [2]. In contrast to conventional canonical statistical analysis methods, our method provides a scheme for the systematic identification and classification of transitions. Microcanonical entropies needed for the analysis were obtained in extensive replica-exchange Mont Carlo simulations [3, 4]. A detailed conformational analysis is performed, and dominant structure types are identified in all phases. |
Wednesday, March 22, 2023 5:24AM - 5:36AM |
UU04.00003: Thermodynamic and topological properties of copolymer rings with a segregation/mixing transition. Esaias J Janse van Rensburg Two ring polymers will be segregated if there is a strong repulsion between monomers in the polymers, and will be in a mixed phase if there is a strong attraction instead. These phases are separated by a segregated-mixed critical point similar to the Θ-point for homopolymers in poor solvents. In this talk self-avoiding polygons are used to model the ring polymers. Some bounds are proven on the free energy of the model, in particular showing that there is a critical point in the phase diagram of the model. Numerical data were obtained using a Multiple Markov Chain implementation using a combination of pivot and Verdier-Stockmayer elementary moves on the polygons. Numerical results on the metric and topological properties of the model will be presented, and it is shown that these properties change when the system passes through the critical point between the segregated and mixed phases. For example, in the segregated phase the data show that the ring polymers are expanded with a low probability of forming topological links, whereas in the mixed phase the ring polymers interpenetrate and are in a collapse state with a higher probability of forming non-trivial links. There is a sharp increase in the linking between the components as the system passes through the critical point. Links between the polygon components are detected by computing the two variable Alexander polynomial and the linking number (which detects homological links). Compactness of the polygons were determined by tracking the number of nearest neighbour contacts, metric properties, and the shape parameters of the model, as a function of the strength of the interaction between the two rings. The model is also appropriate for modeling figure-8 block copolymers with each ring in the figure-8 a block in the copolymer. |
Wednesday, March 22, 2023 5:36AM - 5:48AM |
UU04.00004: Molecular Dynamics Simulation of Entangled Melts at High Rates: Identifying Entanglement Lockup Mechanism Leading to True Strain Hardening Shi-Qing Wang, Yexin Zheng, Mesfin Tsige In the present work, molecular dynamics simulations are carried out based on |
Wednesday, March 22, 2023 5:48AM - 6:00AM |
UU04.00005: All-atom molecular dynamics simulation of solvent diffusion in a glassy polymer Javad Tamnanloo, Mesfin Tsige The diffusion behavior of low molecular weight solvents in a glassy polymer significantly differs from Fickian diffusion and is known as Case II or Class II diffusion. In Case II diffusion, the major experimental observation is that a sharp concentration front moving at a constant speed separates a swollen, rubbery region from a glassy region of the polymer system. Observing Case II diffusion through simulation is very challenging mainly because of the computationally demanding nature of the diffusion process. We have designed a simulation approach to observe Case II type of diffusion in glassy polymers using all-atom simulation. In this presentation, we will share our recent atomistic molecular dynamics simulation results on the diffusion behavior of several low molecular weight solvents in a glassy polystyrene film. Accurate knowledge of the concentration profile of the solvent through the polymer film is crucial in determining the type of the diffusion process and will be the major focus of this presentation. |
Wednesday, March 22, 2023 6:00AM - 6:12AM |
UU04.00006: Correlation Effects in Various Polymer Density-Functional Theories Jiawei Zhang, Baohui Li, Qiang Wang While the widely used polymer self-consistent field theory (SCFT) neglects the effects of system fluctuations and correlations, the latter can be captured by various polymer density-functional theories (PDFTs). Here we directly compare the results of various PDFTs, including those proposed by Yu and Wu (YW), by Chapman and co-workers (miSAFT), and by Donley et al. (CMS-RW), to the results of SCFT and Monte Carlo simulations for selected model systems. We put these PDFTs in a unified computational framework, the same as that of SCFT, and unambiguously quantify the correlation effects that they capture. Our work also reveals the relations among these theories and their computational complexity. |
Wednesday, March 22, 2023 6:12AM - 6:24AM |
UU04.00007: Phase separation in dynamically asymmetric unentangled polymer blend: An experimental study Takeshi Sato, Yumi Matsumiya, Hiroshi Watanabe We examined a phase separation dynamics of a blend of unentangled polyisoprene (PI) and poly(4-ethylstyrene) (PC2St), which exhibits the upper critical solution temperature. Since there is a significant difference in glass transition temperatures of these polymers, these samples are dynamically asymmetric. While PC2St is dielectrically inert, PI has a type-A dipole along the chain backbone and its dynamics can be dielectrically detected. Thus, by combining the dielectric and rheological measurements, we can detect the dynamics of each component in blends. We used this combination to estimate the composition-dependence of the mobility, which is required to describe the phase separation dynamics. For this purpose, we determined the chain friction coefficient (ζ) of each component in a uniform state sufficiently above the phase separation temperature (Ts). The temperature dependence of ζ was reasonably expressed by the Williams–Landel–Ferry (WLF) equation. From the extrapolation of this WLF-type dependence obtained for blends of various compositions to the test temperature T∗ below Ts, ζ at T∗ (ζ∗) can be estimated as a function of the composition. This ζ∗ was then used to determine the mobility Λ defined for the material fluxes at T∗. The time-dependent Ginzburg-Landau equation with this Λ reasonably described the experimental phase-separated structure observed with the optical microscope. |
Wednesday, March 22, 2023 6:24AM - 6:36AM |
UU04.00008: Interaction of Poly(lactic acid) with Water Using FT-IR Spectroscopy under Humidity Conditioning Go Matsuba, Tomoka Kokuzawa, Yuka Ikemoto Introduction |
Wednesday, March 22, 2023 6:36AM - 6:48AM |
UU04.00009: Combined Description of Pressure-Volume-Temperature and Dielectric Relaxation of Several Polymeric and Low-Molecular-Weight Organic Glass-Formers using SL-TS2 Approach Valeriy Ginzburg, Riccardo Casalini, Alessio Zaccone We apply our recently-developed mean-field “SL-TS2” (two-state Sanchez-Lacombe) model to simultaneously describe dielectric a-relaxation time, τα, and pressure-volume-temperature (PVT) data in four polymers (polystyrene, poly(methylmethacrylate), poly(vinyl acetate) and poly(cyclohexane methyl acrylate)) and four organic molecular glass formers (ortho-terphenyl, glycerol, PCB-62, and PDE). Previously, it has been shown that for all eight materials, the Casalini-Roland thermodynamical scaling, τα = f(Tvspγ) (where T is temperature and vsp is specific volume) is satisfied (Casalini, R.; Roland, C. M. Phys. Rev. E 2004, 69(6), 062501). It has also been previously shown that the same scaling emerges naturally (for sufficiently low pressures) within the “SL-TS2” framework (Ginzburg, V. V. Soft Matter 2021, 17, 9094–9106.) Here, we fit the ambient pressure curves for the relaxation time and the specific volume as functions of temperature for the eight materials and observe a good agreement between theory and experiment. We then use the Casalini-Roland scaling to convert those results into “master curves”, thus enabling predictions of relaxation times and specific volumes at elevated pressures. The proposed approach can be used to describe other glass-forming materials, both low-molecular-weight and polymeric. |
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