Article
Chemistry, Physical
Mengkai Feng, Zhonghuai Hou
Summary: We propose a theory to investigate the inertial effect on the glassy dynamics of underdamped active Brownian particle systems. By assuming a nonequilibrium steady-state, an effective Fokker-Planck equation for the probability distribution function (PDF) is obtained. Using this equation, the evolution equation of the intermediate scattering function is derived through the Zwanzig-Mori projection operator method and the mode-coupling theory (MCT). Theoretical analysis reveals that the inertia of the particle affects the memory function and the corresponding glass transition by influencing the structure factor and velocity correlation function. This theory provides theoretical support and guidance for subsequent simulation work.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
Prakash Vardhan, Shankar P. Das
Summary: We studied a field-theoretic model for the metastable liquid and included three-point correlation effects using a nonlocal free-energy functional. We assumed the fragmentation of the free-energy landscape into distinct basins of local minima and evaluated the partition function for the many-particle system through mapping into a composite system of m identical replicas. Static correlations and configurational entropy S-c were calculated in the m = 1 limit, and the obtained Kauzman packing fraction eta(K) is consistent with previous works.
Article
Physics, Fluids & Plasmas
He Huang, Alexei Ivlev, Volodymyr Nosenko, Wei Yang, Cheng-Ran Du
Summary: The propagation of a dissipative soliton was studied experimentally in a two-dimensional binary complex plasma. The crystallization was suppressed in the particle suspension where two types of particles were mixed. Individual particle motions were recorded using video microscopy, and the macroscopic properties of the solitons were measured in the amorphous binary mixture and plasma crystal. Comparisons showed distinct differences in velocity structures and distributions between solitons in the amorphous and crystalline regions. Local structure rearrangement was also observed in and behind the soliton, contrasting with the plasma crystal. Langevin dynamics simulations matched the experimental observations.
Article
Materials Science, Multidisciplinary
Xin-Yuan Gao, Chin-Yuan Ong, Chun-Shing Lee, Cho -Tung Yip, Hai-Yao Deng, Chi -Hang Lam
Summary: The configurational entropy of supercooled liquids extrapolates to zero at the Kauzmann temperature, causing a crisis called the Kauzmann paradox. Using a class of multicomponent lattice glass models, researchers study a resolution of the paradox characterized by a sudden but smooth turn in the entropy as temperature goes sufficiently low. The models demonstrate that the sudden entropy turn occurs when discrete local excitations are largely suppressed.
Article
Chemistry, Physical
Yuxing Zhou, Baicheng Mei, Kenneth S. Schweizer
Summary: This paper combines simulation and Elastically Collective Nonlinear Langevin Equation (ECNLE) theory to study the activated relaxation in monodisperse atomic and polymeric Weeks-Chandler-Andersen (WCA) liquids. The results show that ECNLE theory can accurately describe the density and temperature dependences of the alpha relaxation time of atomic fluids. For polymer fluids, the explicit dynamical effect of local chain connectivity is modeled based on a different parameter. The comparison between atomic and polymeric systems reveals the different effects of chain connectivity on relaxation. The empirical thermodynamic scaling idea works well at high densities or temperatures but fails at low densities and temperatures. The rich and subtle behaviors observed in simulations for atomic and polymeric WCA fluids are well captured by ECNLE theory.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Multidisciplinary Sciences
Matthew A. Harris, Thomas Kinsey, Durgesh Wagle, Gary A. Baker, Joshua Sangoro
Summary: A liquid-liquid transition (LLT) is a transformation from one liquid to another through a first-order transition, fundamental to understanding the liquid state. While LLT has been reported in some materials, experimental evidence for its existence in many molecular liquids remains controversial. Studying the local order and structural dynamics across an LLT provides unprecedented possibilities for understanding the nature of the liquid state.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Chemistry, Multidisciplinary
Mohammad Abdul Sattar
Summary: The increasing number of end-of-life tires globally poses risks to the environment and human health. This study presents an approach using an ionic liquid to adjust the interfacial interactions between carbon black derived from end-of-life tires and natural rubber. The results show that the addition of the ionic liquid improves filler dispersion and cross-linking kinetics, reducing the amount of zinc oxide needed.
Article
Materials Science, Ceramics
G. P. Johari
Summary: By comparing the heat capacity curves of glass and melt, the fictive temperature Tf of the glass can be estimated. It is found that the heat capacity of 20-million-year-old fossil amber and fresh amber are the same at temperatures lower than 273K, and the Tf of fossil amber is 0.89Tg->l. However, using the same heat capacity values violates the basic laws of thermodynamics at temperatures higher than 0K.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2023)
Article
Biochemistry & Molecular Biology
Giuseppe Porpora, Francesco Rusciano, Raffaele Pastore, Francesco Greco
Summary: Glass transition is an intriguing open issue in molecular liquids, and recent research has found that the relationship between macroscopic timescales and cage-jump quantities changes on approaching the glass transition.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Biochemistry & Molecular Biology
Antonio Tripodo, Francesco Puosi, Marco Malvaldi, Dino Leporini
Summary: Research indicates that analysis based on mutual information provides a deeper insight into the transport and relaxation properties of molecular and macromolecular glass formers. Near the glass transition, mutual information reveals different mobility and relaxation properties of particle clusters with filamentous or compact globular structures, especially in the context of dynamical heterogeneity and secondary Johari-Goldstein relaxation processes. Both dynamical heterogeneity and mutual information between orientation and bond displacement reach local maxima at the time scales of primary and JG secondary relaxation, indicating the involvement of rotation/translation coupling in the mechanistic explanation of both phenomena in (macro)molecular systems.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2021)
Article
Chemistry, Physical
Hiroshi Frusawa
Summary: This study focuses on the structure characteristics and degradation mechanism of densely packed spheres, obtaining a metastable DCF through the field-theoretic formulation of stochastic density functional theory and strong-coupling expansion method. The metastable DCF provides the emergence of soft modes at the particle scale, in quantitative agreement with simulation results.
Article
Multidisciplinary Sciences
Yudong Cheng, Qun Yang, Jiangjing Wang, Theodoros Dimitriadis, Mathias Schumacher, Huiru Zhang, Maximilian J. Mueller, Narges Amini, Fan Yang, Alexander Schoekel, Julian Pries, Riccardo Mazzarello, Matthias Wuttig, Hai-Bin Yu, Shuai Wei
Summary: This study provides direct evidence showing a strong correlation between crystallization and beta-relaxations. It is found that by manipulating the beta-relaxation in Ge15Sb85, the crystallization kinetics can be tuned by an order of magnitude. In-situ synchrotron X-ray scattering, dielectric functions, and ab-initio calculations reveal the mechanism behind the weakened beta-relaxation intensity. This research offers a novel approach to controlling the crystallization of PCM.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Kimyung Kim, Soohyun Lee, Taegeun Kim, You Kyoung Chung, Joonsuk Huh, Jaesung Yang, Anna Lee, Keewook Paeng
Summary: The rotational dynamics of fluorescent probes of different sizes in glass-forming materials were studied to understand the relationship between time distribution and length scale of dynamic heterogeneity. The results showed that as the probe size increased, the rotation correlation time shifted to longer times, and the length scale associated with the glass transition was estimated. The estimated length scale roughly matched with calorimetric analysis but was smaller than other measurements, showing a decrease in length scale with an increase in the stretching exponent of the system.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Review
Physics, Multidisciplinary
Vladimir N. Novikov, Alexei P. Sokolov
Summary: This review focuses on the mechanisms that control the steepness of the temperature dependence of structural relaxation in glass-forming liquids. It discusses the specific case of polymeric glass-forming liquids and the possible role of quantum effects in the glass transition.
Article
Chemistry, Physical
Sergey S. Kharintsev, Sergei G. Kazarian
Summary: Thermally induced phase transitions using light at the nanoscale have significant applications in material science. Enhanced optical heating can be achieved with resonant nanostructures. The operating temperature range of a structured heatsink can be controlled to prevent excess heating.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Multidisciplinary Sciences
Baicheng Mei, Yuxing Zhou, Kenneth S. Schweizer
Summary: Understanding the activated dynamics in diverse glass-forming liquids over a wide time range is a challenge in physics, physical chemistry, and materials science. Currently, there is still a lack of a predictive theory that covers both noncooperative and cooperative relaxation. Experimental data has validated a recent microscopic dynamical theory prediction, providing a different conceptual view of the global relaxation map.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Chemistry, Physical
Baicheng Mei, Kenneth S. Schweizer
Summary: The study investigates the effect of external stress on the activated dynamics of dilute spherical penetrant or tracer in dense hard sphere fluids and glasses. It is found that all relaxation processes speed up under stress, and the difference in hopping times between penetrant and matrix decreases significantly.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Baicheng Mei, Yuxing Zhou, Kenneth S. Schweizer
Summary: Through in-depth analysis of experimental data, it was found that the dimensionless compressibility of one-component normal and supercooled liquids of chemically complex nonpolar and weakly polar molecules and polymers follows a simple and general temperature dependence over a wide range of pressures and temperatures. Although hydrogen-bonding liquids display more complex behavior, a new approach was formulated to collapse the temperature- and pressure-dependent dimensionless compressibility data onto a master curve. The dimensionless compressibility scales well as an inverse power law with temperature, with an exponent that decreases with pressure.
JOURNAL OF PHYSICAL CHEMISTRY B
(2021)
Article
Polymer Science
Baicheng Mei, Yuxing Zhou, Kenneth S. Schweizer
Summary: The connection between slow activated relaxation in glass-forming liquids and various equilibrium thermodynamic properties is debated. The microscopic elastically collective nonlinear Langevin equation theory predicts a noncausal connection between dynamics and thermodynamics, experimentally verified in both molecular and inorganic glass-forming liquids. Predictions include a power law scaling of the activation barrier with inverse temperature and a fragile-to-strong crossover in temperature space.
Article
Chemistry, Physical
Yuxing Zhou, Baicheng Mei, Kenneth S. Schweizer
Summary: This paper combines simulation and Elastically Collective Nonlinear Langevin Equation (ECNLE) theory to study the activated relaxation in monodisperse atomic and polymeric Weeks-Chandler-Andersen (WCA) liquids. The results show that ECNLE theory can accurately describe the density and temperature dependences of the alpha relaxation time of atomic fluids. For polymer fluids, the explicit dynamical effect of local chain connectivity is modeled based on a different parameter. The comparison between atomic and polymeric systems reveals the different effects of chain connectivity on relaxation. The empirical thermodynamic scaling idea works well at high densities or temperatures but fails at low densities and temperatures. The rich and subtle behaviors observed in simulations for atomic and polymeric WCA fluids are well captured by ECNLE theory.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Baicheng Mei, Bilin Zhuang, Yuyuan Lu, Lijia An, Zhen-Gang Wang
Summary: By introducing the concept of local-average free volume, this study reveals the correlation between dynamic heterogeneity and the average local free volume in glass formers, resolving the controversy regarding the role of free volume in particle rearrangements.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Polymer Science
Baicheng Mei, Tsai-Wei Lin, Grant S. Sheridan, Christopher M. Evans, Charles E. Sing, Kenneth S. Schweizer
Summary: In this study, a coordinated experimental, simulation, and theoretical investigation was conducted to explore how permanent polymer network cross-links impact the segmental relaxation time at various temperatures and glass transition temperature criteria. The results showed that tight cross-linking leads to a significant increase in the segmental relaxation time and elevation of Tg, which grows roughly linearly with cross-link fraction beyond a certain threshold. Additionally, the use of cross-link fraction dependent dynamic Tg achieved a remarkably good collapse of Angell plots for different cross-link densities and dynamic vitrification time scale criteria. The findings were successfully explained by the elastically collective nonlinear Langevin equation (ECNLE) theory, demonstrating a microscopic understanding of the experimental and simulation observations in terms of cross-link fraction dependent coupled local cage and nonlocal collective elastic barriers. Overall, excellent agreement between experiment, theory, and simulation was observed.
Article
Polymer Science
Baicheng Mei, Kenneth S. Schweizer
Summary: We apply a statistical mechanical theory to study the influence of polymer connectivity and penetrant-polymer attractive interactions on the hopping rate of penetrants in glass-forming liquids. We investigate the modifications of the penetrant activation barriers caused by attractions of variable strength and spatial range. Our findings reveal the importance of factors such as physical bonding, steric caging, local caging, and long-range matrix collective elasticity in determining penetrant transport selectivity.
Article
Multidisciplinary Sciences
Baicheng Mei, Grant S. Sheridan, Christopher M. Evans, Kenneth S. Schweizer
Summary: Understanding the transport of penetrant or tracer atoms and molecules in condensed phases is a challenging problem. A recent microscopic theory has predicted a correlation between penetrant diffusivity and the matrix thermodynamic compressibility, as well as an activation barrier that scales with the ratio of penetrant-to-matrix size. Experimental data supports these predictions, indicating a reduction in chemical complexity. These findings have implications for glassy dynamics and various applications.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Chemistry, Physical
Baicheng Mei, Tsai-Wei Lin, Charles E. E. Sing, Kenneth S. S. Schweizer
Summary: We generalize a microscopic statistical mechanical theory to study the influence of crosslinking in polymer networks on the penetrant relaxation time and diffusivity. Our calculations are relevant to recent experimental studies of a nm-sized molecule diffusing in polymer networks. The results show that the penetrant relaxation time increases with the glass transition temperature, which is linearly related to the square root of the crosslink fraction. A model for the penetrant diffusion constant is proposed, combining activated relaxation and entropic mesh confinement. This behavior corresponds to a new network-based type of decoupling of diffusion and relaxation.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Baicheng Mei, Tsai-Wei Lin, Grant S. Sheridan, Christopher M. Evans, Charles E. Sing, Kenneth S. Schweizer
Summary: The transport of penetrants through dense cross-linked polymer networks is influenced by various factors such as cross-link density, size ratio, and temperature. This study used a combination of experiment, simulation, and theory to investigate these effects and found that the coupling between local penetrant hopping and polymer structural relaxation is crucial, while mesh confinement effects are less important. The findings provide insights into the behavior observed in experiment and simulation and may contribute to the development of improved polymer membrane designs.
ACS CENTRAL SCIENCE
(2023)
Article
Polymer Science
Michael Q. Tu, Oleg Davydovich, Baicheng Mei, Piyush K. Singh, Gary S. Grest, Kenneth S. Schweizer, Thomas C. O'Connor, Charles M. Schroeder
Summary: In this work, the slow stress relaxation behavior of concentrated ring polymers is reported, which is caused by ring-ring interactions and ring packing structure. Topologically pure, high molecular weight ring polymers are prepared without linear chain contaminants. Experimental results are in good agreement with molecular dynamics simulations, which show non-power-law stress relaxation due to ring-ring interpenetrations. These findings provide a new understanding of ring polymer physics.
Article
Chemistry, Physical
Tsai-Wei Lin, Baicheng Mei, Kenneth S. Schweizer, Charles E. Sing
Summary: The role of cross-linked network polymers in governing the molecular motion of penetrants is investigated using molecular simulation. The results show that cross-links primarily affect molecular diffusion through the modification of the matrix glass transition, and penetrant transport is affected by dynamic heterogeneity at low temperatures. This research provides important insights for the design of materials for applications such as coatings and membranes.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Baicheng Mei, Kenneth S. Schweizer
Summary: The article applies the microscopic self-consistent cooperative hopping theory to study the activated penetrant dynamics in polymer melts and crosslinked networks. It focuses on the role of highly variable non-spherical molecular shape and examines its impact on penetrant hopping over a wide range of temperatures. The study reveals that the shape of the penetrant has a significant influence on its activated relaxation, with larger penetrants showing a stronger shape-dependence. A variable aspect ratio is proposed to describe the effect of penetrant shape on the relaxation times.
Article
Chemistry, Physical
Baicheng Mei, Kenneth S. Schweizer
Summary: This study employs the microscopic self-consistent cooperative hopping theory to investigate penetrant activated dynamics in glass forming viscous liquids and colloidal suspensions. The research focuses on the mean activated relaxation time, diffusion constant, and local cage barriers of smaller tracers in relation to larger particle matrices. The results show non-monotonic variations in the decoupling between matrix and penetrant alpha relaxation times with packing fraction, and establish a dynamics-thermodynamics power law connection between penetrant activation barrier and matrix dimensionless compressibility.
