Article
Chemistry, Physical
Piotr Polanowski, Andrzej Sikorski
Summary: This study simulated the structure of two-dimensional polymer chains in a solvent using the Cooperative Motion Algorithm and revealed the differences compared to chain-like structures in dense polymer liquids.
Review
Polymer Science
Debashish Mukherji, Kurt Kremer
Summary: Polymeric materials are widely used in various aspects of our daily life. Smart polymers, which can undergo significant structural and functional changes in response to slight external stimuli, have attracted considerable attention. The design of lightweight high-performance organic solids with tunable properties using different interactions, especially hydrogen bonds, is a challenge. This review summarizes recent developments in the field of smart polymers and discusses their solution processing and applications in organic solids, aiming to provide a microscopic understanding for future experiments and simulations in designing advanced functional materials.
Article
Chemistry, Physical
Nico F. A. van der Vegt
Summary: The study of molecular mechanisms for cosolvent-driven hydrophobic polymer collapse transitions in water is crucial for the field of smart responsive materials. While new phenomena have been discovered and understood, the elementary mechanisms contributing to polymer coil-globule transitions in different cosolvent-water systems remain unclear.
JOURNAL OF PHYSICAL CHEMISTRY B
(2021)
Article
Chemistry, Physical
S. Das, N. Kennedy, A. Cacciuto
Summary: The study investigates the structural transition of an active fully flexible self-avoiding polymer under the influence of different qualities of embedding solvent and active forces. The findings suggest that a simple rescaling of temperature can qualitatively capture the dependence of the polymer's Theta point on the amplitude of active fluctuations. The study also proposes the presence of negative active pressure between monomers in active polymers, similar to what has been found in suspensions of active hard spheres.
Article
Chemistry, Multidisciplinary
Renata L. Sala, Tiago Venancio, Emerson R. Camargo
Summary: Nanocomposite hydrogels were characterized under temperature stimuli using UV-vis spectroscopy and NMR relaxation techniques, revealing changes in phase transition patterns and behaviors due to the formation of an interconnected system of silica and polymer chains with reduced enthalpic contribution and mobility. Water molecule and polymer segment motions in the nanocomposites showed wider temperature range for absorption and release of water, and polymer segments responded differently to phase transition in the presence of silica. These techniques demonstrated the potential for studying multicomponent nanocomposites with diverse functionalities and dynamic properties.
Article
Chemistry, Physical
Letizia Tavagnacco, Ester Chiessi, Emanuela Zaccarelli
Summary: Extensive molecular dynamics simulations have provided microscopic insights into the coil-to-globule transition of PNIPAM, showing a reentrant behavior of the critical temperature at high pressures and the existence of a new globular state with a more structured hydration shell. This study indicates that temperature and pressure induce the transition through different molecular mechanisms, offering a way to systematically tune the properties of the PNIPAM states.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Xiangxiang Gao, Xiaofei Xu
Summary: The study used molecular dynamics simulations to investigate the dynamics of linear polyelectrolyte knot in solution with doping salt. The coupling results of chain entanglement and knot fluctuations were explained, with the movement effect being important when the chain is in a random coil state. The breathing effect dominates the knot dynamics in the close-to-globule state, especially when high concentrations of doping salt or high-valent salt are present.
MOLECULAR SIMULATION
(2022)
Article
Chemistry, Physical
Osama M. Alkhudhari, Amal Altujjar, Muhamad Z. Mokhtar, Ben F. Spencer, Qian Chen, Andrew G. Thomas, Nigel W. Hodson, Xuelian Wang, Patrick Hill, Janet Jacobs, Richard J. Curry, Brian R. Saunders
Summary: This study demonstrates the use of large polymer microgel particles as additives in semitransparent perovskite solar cells, resulting in the formation of 2D nanopore arrays in the perovskite layer. This unique morphology improves the performance of the solar cells and may accelerate the development of semitransparent perovskite solar cells.
JOURNAL OF MATERIALS CHEMISTRY A
(2022)
Article
Polymer Science
Antonio L. Medina-Castillo, Modesto T. Lopez-Lopez, Maria Dolores Fernandez-Ramos
Summary: This paper presents, for the first time, the theoretical formulation of the distribution function of critical nuclei under Pre-Poly conditions. It also develops a simple empirical method to calculate the concentration of critical nuclei, which shows good agreement with theoretical calculations.
Article
Biology
Andrea Pica, Giuseppe Graziano
Summary: Elastin-like polypeptides (ELPs) are soluble in water at low temperature but undergo a reversible coil-to-globule collapse transition upon increasing the temperature. The addition of trimethylamine N-oxide (TMAO), glycine, or betaine to water causes a significant decrease in the collapse temperature (T(collapse)) of a specific ELP. An alternative approach based on the solvent-excluded volume effect and its temperature dependence is able to explain the ELP collapse and the lowering of T(collapse) induced by the addition of TMAO, glycine, or betaine.
Article
Chemistry, Physical
Yuka Hiei, Ikuya Ohshima, Mitsuo Hara, Takahiro Seki, Taiki Hoshino, Yukikazu Takeoka
Summary: This study investigated the effects of monomer arrangement and composition for star-shaped polymers on the shrinkage behavior of polymer gels. The results showed that introducing more than 20% DMA as a block copolymer increased the shrinkage speed of the gels.
Article
Chemistry, Multidisciplinary
Eric Weissenborn, Joern Droste, Michael Hardt, Daniel Schlattmann, Celine Tennagen, Christian Honnigfort, Monika Schoenhoff, Michael Ryan Hansen, Bjoern Braunschweig
Summary: By E/Z photo-isomerization, the hydrophobic interactions between HPC polymers and AAP surfactants can be altered; the interaction between E-AAP and HPC is strong, leading to a significant increase in the critical temperature of the polymer phase transition, while the hydrophobic interactions between HPC and Z-AAP are drastically reduced.
CHEMICAL COMMUNICATIONS
(2021)
Article
Chemistry, Inorganic & Nuclear
Sujit Kamilya, Sakshi Mehta, Rodrigue Lescouezec, Yanling Li, Jiri Pechousek, Mohini Semwal, Abhishake Mondal
Summary: A two-step thermo-induced spin-state switching was observed in a cyanide-bridged [Fe2Fe2] molecular square complex. The low-temperature ground state transformed into the high-temperature state via a stable intermediate phase. Additionally, the desolvated phase also exhibited gradual and reversible thermo-induced spin state change as well as photo-induced spin-state switching at 20 K.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Physical
Marcin Pastorczak, Michal Nejbauer, Naoki Shinyashiki, Masanobu Takatsuka, Gonzalo Angulo, Yuriy Stepanenko, Czeslaw Radzewicz
Summary: The study observed for the first time the sub-nanosecond stage of the coil-to-globule transition of a polymer in water, which was made possible by a novel experimental approach. The increase in light scattering intensity around 300-400 ps after a temperature jump above the LCST suggests the rapid formation of local nuclei along the polymer chain in the observed stage of the transition.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Polymer Science
Arne Lerch, Florian Kaefer, Sylvain Prevost, Seema Agarwal, Matthias Karg
Summary: Copolymerization is a powerful method that offers access to new polymer materials with tailored responses to external stimuli. In this study, the phase transition of polymers in heavy water was studied using small-angle neutron scattering. The results showed that interchain interactions are present below the cloud point, while polymer-polymer interactions become more prominent above the cloud point.
Article
Chemistry, Multidisciplinary
Xuan Zhang, Yongtao Wang, Jia Yao, Haoran Li, Kenji Mochizuki
Summary: Through molecular dynamics simulations, we studied the properties of pure liquid primary alcohols at ambient conditions, demonstrating that small increases in partial charges can improve the accuracy of simulation results for dynamics, structure, and thermodynamic properties.
JOURNAL OF COMPUTATIONAL CHEMISTRY
(2022)
Article
Chemistry, Physical
Hidefumi Naito, Ryuichi Okamoto, Tomonari Sumi, Kenichiro Koga
Summary: Through molecular simulation, it has been found that the strength of hydrophobic interaction varies with the molecular size following a power law, which is different from the cubic power law observed in the second virial coefficients of gases.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Biochemistry & Molecular Biology
Yasuhiro Isogai, Hiroshi Imamura, Tomonari Sumi, Tsuyoshi Shirai
Summary: Living cells with high concentrations of biomolecules have evolved globular proteins to increase their solubility. The O-2-storage protein myoglobin (Mb) in diving mammals has evolved to maintain high solubility under crowding conditions or increase tolerance against macromolecular precipitants. The study shows that precipitant tolerance is related to the surface net charges (Z(Mb)) of Mb molecules and can be explained by electrostatic repulsion.
Article
Multidisciplinary Sciences
Tomonari Sumi, Kouji Harada
Summary: COVID-19 is typically a mild to moderate disease in healthy individuals but can potentially cause life-threatening illness and persistent symptoms. Age is the main determinant of disease severity due to a decline in immune response. A mathematical model of the immune response to SARS-CoV-2 revealed that age-related risk factors and ongoing immune response contribute to increased viral load, making it difficult for some patients with mild or severe symptoms to effectively eliminate the virus and potentially develop long COVID.
Article
Physics, Multidisciplinary
Joseph O. Indekeu, Kenichiro Koga
Summary: The dihedral contact angles between interfaces in three-fluid-phase equilibria must be continuous functions of the bulk thermodynamic fields. A nonwetting gap in the phase diagram is predicted by this argument, challenging the common belief in critical-point wetting. Experimental results support this argument, showing that complete wetting is only found in a small vicinity of the tricritical point, while nonwetting prevails outside this region.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
Tomonari Sumi, Kouji Harada
Summary: The forebrain cholinergic system promotes higher brain function through the M1 muscarinic acetylcholine receptor (mAChR). mAChR also induces long-term potentiation (LTP) and long-term depression (LTD) of excitatory synaptic transmission in the hippocampus. This study suggests that mAChR-dependent LTP/LTD shares a common AMPAR trafficking pathway with NMDAR-dependent LTP/LTD. Additionally, Ca2+ influx during M1 mAChR activation is induced by Ca2+ stored in the ER and mediated by IP3 receptors, unlike NMDAR.
Article
Biochemistry & Molecular Biology
Noa Nakata, Ryuichi Okamoto, Tomonari Sumi, Kenichiro Koga, Takeshi Morita, Hiroshi Imamura
Summary: Alcohols and urea are widely used as protein denaturants due to their properties. 2,2,2-trifluoroethanol (TFE) acts as a helix stabilizer, while urea efficiently denatures ordered native structures. The molecular mechanism behind the cosolvent effects of TFE and urea on protein stability is still controversial.
Article
Biochemistry & Molecular Biology
Noa Nakata, Ryuichi Okamoto, Tomonari Sumi, Kenichiro Koga, Takeshi Morita, Hiroshi Imamura
Summary: Alcohols and urea have different cosolvent effects on proteins, with TFE acting as a helix stabilizer and urea denaturing helices. Molecular dynamics simulations revealed that the helix stabilization by TFE is due to electrostatic interactions between TFE and side chains, while the coil stabilization by urea is attributed to electrostatic and dispersion interactions between urea and the main chains.
Article
Chemistry, Physical
Aoi Taira, Ryuichi Okamoto, Tomonari Sumi, Kenichiro Koga
Summary: This study investigates the solvation free energies of amphiphilic species (methanol and 1,2-hexanediol) as a function of temperature or pressure using molecular dynamics simulations combined with efficient free-energy calculation methods. The results demonstrate the accuracy of the perturbation combining method for obtaining solvation free energies of amphiphilic solutes, and provide insights into the contributions of different factors to the solvation free energy.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Hidefumi Naito, Tomonari Sumi, Kenichiro Koga
Summary: In this study, we quantitatively examine the dependence of effective interactions between nonpolar solutes in water and a simple liquid on solute size. High-accuracy calculations of mean force potentials (w(r)) and osmotic second virial coefficients (B) are performed using molecular dynamics simulations. The results demonstrate that as the solute diameter increases, the first minimum of w(r) becomes lower and B increases proportionally to sigma(alpha) with a power close to 6 or 7, confirming the solute-size dependence of B observed previously for a smaller range of sigma. Additionally, the study shows that the strength of attractive interactions between solute and solvent molecules can qualitatively alter the characteristics of the effective pair interaction between solute particles in both water and a simple liquid.
FARADAY DISCUSSIONS
(2023)
Article
Chemistry, Physical
Hiroyo Ohgi, Hiroshi Imamura, Tomonari Sumi, Keiko Nishikawa, Yoshikata Koga, Peter Westh, Takeshi Morita
Summary: The study found that in the TFE-H2O mixture, concentration fluctuations of TFE molecules and various interactions between molecules have a significant impact on helix formation of proteins/peptides.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
