Article
Polymer Science
Dong-Dong Wang, Kai-Feng Yu, Xiao-Lei Xu, Wen-Sheng Xu
Summary: It has been found that the unique relaxation property of multi-arm star polymers leads to unusual rheological behaviors. The stress-strain response of multi-arm star polymer melts differs from that of star polymers with a small number of arms, and a double stress overshoot appears when the flow strength is comparable to the relaxation time of the star polymers.
CHINESE JOURNAL OF POLYMER SCIENCE
(2022)
Article
Polymer Science
Jon Maiz, Ester Verde-Sesto, Isabel Asenjo-Sanz, Paula Malo de Molina, Bernhard Frick, Jose A. Pomposo, Arantxa Arbe, Juan Colmenero
Summary: In this study, the impact of internal cross-links on the properties of polymer melts was investigated using various techniques. It was found that internal cross-links do not significantly alter local properties and fast dynamics, but do slow down the alpha-relaxation process. Additionally, broader response functions and stronger deviations from Gaussian behavior were observed in the SCNPs melt, hinting at additional heterogeneities. Furthermore, rheological properties were clearly affected by internal cross-links.
Article
Chemistry, Multidisciplinary
Meiling Chen, Zhihua Lin, Mingjun Xuan, Xiankun Lin, Mingcheng Yang, Luru Dai, Qiang He
Summary: Control over dynamic assembly, disassembly, and reconfiguration of light-activated MoS2 colloidal motor swarms has been achieved through a photochemical reaction generating chemical gradients. Self-diffusiophoresis induced by locally consumed oxygen gradient drives phototactic process, allowing external regulation of collective migration and shapes. The programmable swarm transformation provides proof-of-concept for active soft materials with adaptive and interactive functions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Physics, Fluids & Plasmas
L. H. Miranda-Filho, T. A. Sobral, A. J. F. de Souza, Y. Elskens, Antonio R. de C. Romaguera
Summary: This article discusses the dynamical phase transition in Vicsek systems and investigates their chaotic behavior by computing the largest Lyapunov exponent (LLE). The authors find a chaotic regime for the collective behavior of the self-propelled particles (SPPs) based on the LLE and observe a significant change in the dependence of LLE on applied noise near the known transition points of the Vicsek model.
Article
Engineering, Electrical & Electronic
Sida Mu, Lingyun Wang, Guangxi Li
Summary: This article investigates the problem of motion blur in images captured by star sensors under high dynamic conditions, which affects the accuracy of attitude calculation. The authors derive the imaging model for blurred star spots and propose a method to fit the trajectory of star spots using the least-squares method and simulated annealing algorithm. The feasibility and effectiveness of the method are validated through simulations and experiments, with a fitting error reduction of at least 0.1 pixel compared to previous studies.
IEEE SENSORS JOURNAL
(2023)
Article
Polymer Science
Maximilian Piszko, Tobias Schaible, Christian Bonten, Andreas P. Froeba
Summary: This study demonstrates the applicability of dynamic light scattering for the characterization of molecular mass and thermal transport in mixtures consisting of a polymer melt and a blowing agent. The experimental uncertainties of the obtained diffusivities in the studied mixtures have a minimum value close to 3% and average around 13% for thermal diffusivity and 7.4% for mutual diffusivity.
Article
Physics, Multidisciplinary
Parisa Rahmani, Fernando Peruani, Pawel Romanczuk
Summary: The study reveals that in active systems with topological interactions, spatial heterogeneities can maintain long-range order and enhance the emergence of traveling bands. Topological flocking models in heterogeneous environments exhibit features similar to metric models, with spatial heterogeneities inducing an effective density-order coupling that facilitates the emergence of traveling bands.
COMMUNICATIONS PHYSICS
(2021)
Article
Instruments & Instrumentation
Jingyun Liu, Galina Gorbacheva, Haibao Lu, Jiazhi Wang, Yong-Qing Fu
Summary: Modeling the dynamic heterogeneity in amorphous shape memory polymers (SMPs) is a challenging task due to the complex statistical properties of strain energy distributions. In this study, the influences of temperature rates and strain rates on strain energy evolution in SMPs were investigated for the first time, taking into account the dynamic equilibria. A phase transition model incorporating Gaussian distribution statistics was proposed to study the glass transition heterogeneity and tailorable mechanics in amorphous SMPs. The analytical results were compared with experimental data, demonstrating good agreement.
SMART MATERIALS AND STRUCTURES
(2022)
Article
Multidisciplinary Sciences
Ondrej Kucera, Jeremie Gaillard, Christophe Guerin, Manuel Thery, Laurent Blanchoin
Summary: By combining microtubules and actin filaments and utilizing a feedback loop, we have created an artificial active cytoskeletal composite that exhibits both structural stability and plasticity. The system is sensitive to external stimuli and shows potential for self-regulation.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Multidisciplinary Sciences
Stef Van Havermaet, Pieter Simoens, Tim Landgraf, Yara Khaluf
Summary: Shepherding is an essential skill for guiding a herd in a desired direction and can be applied to various scenarios such as crowd control and rescue missions. Equipping robots with the ability to shepherd can improve efficiency and reduce labor costs. This study proposes a decentralized control algorithm for multi-robot shepherding, where the robots maintain a caging pattern around the herd to detect potential dangers. Simulations show that the proposed algorithm is successful in shepherding when the herd remains cohesive and enough robots are deployed.
ROYAL SOCIETY OPEN SCIENCE
(2023)
Article
Physics, Fluids & Plasmas
Monika Sanoria, Raghunath Chelakkot, Amitabha Nandi
Summary: The softening of interaction of active particles destabilizes the highly ordered dense phase, resulting in the formation of a porous cluster spanning the system. The system also exhibits standard percolation transition characteristics when the particle motility exceeds a critical value. Additionally, similar transitions are observed in the athermal limit, even at low motility. The phase diagram of repulsive active particles is revealed to be richer than previously conceived.
Article
Engineering, Environmental
Jiankai Ge, Baron Peters
Summary: Various heterogeneous catalysts are being developed for plastic recycling, most of which operate in viscous polymer melts. The external mass transfer effects in these melts can inhibit the supply of co-reactants and the diffusion of long chain products away from the catalyst after each cut. This can unintentionally confer processivity to catalyst operation.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Sophia Y. Chan, Mayank Jhalaria, Yucheng Huang, Ruipeng Li, Brian C. Benicewicz, Christopher J. Durning, Thi Vo, Sanat K. Kumar
Summary: Polymer-grafted nanoparticle membranes show unexpected gas transport enhancements, but the structural origins of this behavior are unclear. This study measured and interpreted data on grafted nanoparticles and found that as the graft molecular weight increases, the gas transport enhancement decreases.
Article
Polymer Science
Aristotelis Zografos, Helena A. All, Alice B. Chang, Marc A. Hillmyer, Frank S. Bates
Summary: A series of model poly((+/-)-lactide) graft copolymers were synthesized and used to study the transition from star-like to bottlebrush structure in shear and extensional flows. Small-amplitude oscillatory shear and extensional rheometry measurements were conducted on samples with different backbone degrees of polymerization. The transition from star-like to bottlebrush structure occurred at a backbone degree of polymerization between 50 and 69. In extensional flows, the star-like melts exhibited no melt strain hardening, while the bottlebrush melts showed prominent strain hardening. These findings are important for designing bottlebrush materials with strain hardening properties for various processing methods involving extensional flows.
Article
Chemistry, Physical
Benjamin Sorkin, Avraham Be'er, Haim Diamant, Gil Ariel
Summary: A major challenge in the study of active matter is quantitatively characterizing phases and transitions. This study shows how entropy analysis can be used to classify spatial patterns and regimes in collective behavior. The analysis estimates the contributions of position and orientation correlations to total entropy, pinpointing the flocking transition in the Vicsek model and providing insight into the physical mechanism behind it. Additionally, when applied to experiments on swarming Bacillus subtilis with different cell aspect ratios and overall bacterial area fractions, the entropy analysis reveals a rich phase diagram with transitions between qualitatively different swarm statistics. The physical and biological implications of these findings are discussed.
Article
Chemistry, Physical
Alexandros Chremos
JOURNAL OF CHEMICAL PHYSICS
(2020)
Article
Polymer Science
Daniel F. Sunday, Alexandros Chremos, Tyler B. Martin, Alice B. Chang, Adam B. Burns, Robert H. Grubbs
Article
Chemistry, Multidisciplinary
Zhiwei Lin, Hamed Emamy, Brian Minevich, Yan Xiong, Shuting Xiang, Sanat Kumar, Yonggang Ke, Oleg Gang
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2020)
Article
Polymer Science
Hamed Emamy, Sanat K. Kumar, Francis W. Starr
Article
Polymer Science
Ari Y. Liu, Hamed Emamy, Jack F. Douglas, Francis W. Starr
Summary: This study investigates how chain length affects the structure and segmental dynamics of polymer-nanoparticle composites at semidilute nanoparticle concentrations using molecular dynamics simulations. The presence of bridging chains between nanoparticles has a small impact on the overall nanocomposite segmental relaxation time, even though these chains require significant elongation to bridge between nanoparticles.
Article
Chemistry, Physical
Ferenc Horkay, Alexandros Chremos, Jack F. Douglas, Ronald Jones, Junzhe Lou, Yan Xia
Summary: The study systematically investigates the structures of model synthetic and natural bottlebrush polyelectrolyte solutions using experimental techniques and molecular dynamics simulations. While both types of solutions tend towards supramolecular organization, a distinct polyelectrolyte peak is observed in bottlebrush poly(sodium acrylate) solutions but not in aggrecan solutions, attributed to the interplay of polymer topology and solvation effects. The tunable solution organization and properties of polyelectrolytes have significant implications for biological function, disease, and various materials applications.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Polymer Science
Wengang Zhang, Jack F. Douglas, Alexandros Chremos, Francis W. Starr
Summary: When simulating the structure and dynamics of star polymer films, the topology of the star polymers significantly affects the relaxation rate and relaxation time of the entire film. The changes in polymer topology also alter the mobility gradients in the film.
Article
Chemistry, Physical
Alexandros Chremos, Ferenc Horkay, Jack F. Douglas
Summary: We investigated the conformational properties of ideal nanogel particles with lattice network topology using molecular dynamics simulations. Our study quantifies the impact of polymer topology on the solution properties of these branched molecular architectures, revealing competing trends and a crossover in particle-like and linear polymer-like characteristics. Additionally, our calculations show the emergence of primary scattering peaks and distinct power-law regimes in relation to the nanogel particle size and mesh size. Increasing mesh size leads to similar scaling as infinite Gaussian chains, highlighting the importance of molecular parameters on the structure of nanogel particles.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Alexandros Chremos, Ferenc Horkay, Jack F. Douglas
Summary: In this study, a method to generate various randomly branched polymeric structures was proposed to investigate how polymer topology encodes a configurational structure in a solution. It was found that by introducing bonding defects, compact nanogel particles can transform into open fractal structures with an inherent anisotropy. The structure of these polymers also changes as the network decimation increases.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Polymer Science
Alexandros Chremos, Jack F. Douglas, Peter J. Basser, Ferenc Horkay
Summary: This study computationally investigates a composite hydrogel as a biomimetic model to mimic the unique load-bearing properties of articular cartilage, and reveals that the emergence of prestress in the composite gels is primarily caused by the stiffness of the polymer matrix and the asymmetry in the enthalpic interactions.
Article
Chemistry, Physical
Alexandros Chremos, Jack F. Douglas, Peter J. Basser, Ferenc Horkay
Summary: This study investigates the solution and osmotic properties of uncharged compact nanogel particles under different solvent qualities and particle concentrations through molecular dynamics simulations. The research reveals that improving solvent quality enhances spatial segmental uniformity, while heterogeneous structures appear near the theta-point.
Article
Chemistry, Multidisciplinary
Hamed Emamy, Francis W. Starr, Sanat K. Kumar
Summary: Strong attractions between polymer-nanoparticles can lead to the spontaneous formation of a polymer layer with distinct dynamic characteristics at the nanoparticle interface. When investigating how nanoparticle mobility affects the signature of the bound layer, it was found that for small, relatively mobile nanoparticles, the bound layer is linked to the motion of the nanoparticle, causing the relaxation signature of the bound layer to essentially disappear in the intermediate scattering function.
Article
Physics, Fluids & Plasmas
Alexandros Chremos, Ferenc Horkay
Article
Materials Science, Multidisciplinary
Alexandros Chremos, Ferenc Horkay