Article
Materials Science, Multidisciplinary
Byungjo Kim, Hyunseong Shin, Joonmyung Choi, Maenghyo Cho
Summary: A multiscale modeling approach is proposed to investigate the interfacial load transfer characteristics of epoxy nanocomposites, examining the stress evolutions with molecular dynamics simulations and studying atomic motions in the matrix phase. The distinct structural features in a highly crosslinked system induce a cohesive motion under mechanical loading, favoring internal load transfer. Interfacial load transfers with curing conversion of epoxies are taken into account in an equivalent FE model with a weakened interface concept.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
(2022)
Article
Chemistry, Physical
Mark A. Wilson, Amalie L. Frischknecht
Summary: High-pressure storage and cyclic (de)pressurization of hydrogen can cause damage to gas canisters and materials, but adjusting the crosslink density can reduce the risk of damage.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Polymer Science
Xiangrui Zheng, Hua Yang, Yaguang Sun, Yongqin Zhang, Yafang Guo
Summary: The paper investigates the self-healing mechanism based on disulfide bond exchange reactions at the atomic scale through molecular dynamics simulations. It explores the effects of crosslink density and healing time on self-healing efficiency and mechanical properties. The results show that high crosslink density improves mechanical properties but reduces molecular chain mobility, while shorter stress relaxation time leads to higher healing efficiency.
Article
Materials Science, Ceramics
Dawei Sun, Jiaxin Wang, Hui Wang, Zheng Yan, Wenxu Ma, Xiaoyu Ma, Yali Wang, Zhongcheng Ma, Xiaodong Jin, Shibing Sun, Suping Cui, Zhiyong Wang
Summary: This study investigates the interaction between load-induced broken panels of C-S-H gel and cured epoxy resins with different crosslink densities (e.g., 0.23, 0.77, and 0.97) using molecular dynamics methods. The results show that crosslink density plays a crucial role in the geometrical size and atom distributions. Low crosslink density leads to phase separation due to the aggregation of amine molecules, while high crosslink density results in high porosity in the interfacial region, degrading the mechanical performance of materials.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2023)
Article
Polymer Science
Haoxiang Li, Haoyu Wu, Wenfeng Zhang, Xiuying Zhao, Liqun Zhang, Yangyang Gao
Summary: This study investigates the rheological properties of polymer nanocomposites using reverse nonequilibrium molecular dynamics simulation, and finds that shear rate has a significant impact on shear viscosity and chain extension. The increase in volume fraction of nanoparticles and polymer-NP interaction leads to a higher zero-shear viscosity, attributed to the formation of network structures causing delayed dynamics. Additionally, both the first and second normal stress differences exhibit power laws with shear rate.
Article
Polymer Science
Yafei Wang, Zhicheng Chang, Ke Gao, Ziwei Li, Guanyi Hou, Jun Liu, Liqun Zhang
Summary: The study found that MoS2 and BN fillers enhance thermal conductivity with increasing sizes but have different effects on the composites; the introduction of hybrid BN/MoS2 filler effectively reduces voids in the composites and increases thermal conductivity; there exists an optimal loading ratio of the two fillers, reaching the maximum thermal conductivity of the composite.
Article
Thermodynamics
Xiao Wan, Baris Demir, Meng An, Tiffany R. Walsh, Nuo Yang
Summary: Epoxy resins are widely used polymer matrices for various applications, but the molecular-level knowledge needed to fully exploit their potential is still limited. This study uses molecular dynamics simulations to explore the relationships between thermal conductivity, mechanical properties, and cross-linking degree in an exemplar epoxy resin. The results suggest that both the elastic modulus and thermal transport of the resin increase with greater cross-linking, providing insights for designing customized epoxy resins with desirable thermal and mechanical attributes.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Chemistry, Physical
Simon A. N. Alberti, Jurek Schneider, Florian Mueller-Plathe
Summary: In this study, the mobility behavior of polymer chains in polymer nanocomposites under confinement was investigated using computational simulations. It was found that the confinement of nanotubes significantly affected the diffusion, with increased diffusion observed in the direction parallel to the nanotubes. The polymer chains were observed to align parallel to the nanotubes and experience compression in the orthogonal direction. Increasing the volume fraction of nanotubes further increased the diffusion parallel to the nanotubes.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Biochemistry & Molecular Biology
Wei-Han Hui, Yen-Lin Chen, Shu-Wei Chang
Summary: Crosslinking affects the mechanical behavior and tissue metabolism of collagen-based tissues. Aging and diabetes alter the crosslinking type and density, thus changing tissue properties. High-connectivity enzymatic crosslinking and advanced-glycation end-products result in uniform deformation under daily activity, while low-connectivity enzymatic crosslinking does not. High-connectivity model displays more sliding, while AGEs induce instability in structures near the binding sites.
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
(2024)
Article
Polymer Science
Zepeng Wang, Minglong Su, Xinwu Duan, Xiulong Yao, Xiaoying Han, Junping Song, Lianxiang Ma
Summary: In this study, the thermomechanical and tribological properties of graphene-reinforced natural rubber were investigated using molecular dynamics simulations. It was found that the addition of graphene significantly improved the strength, thermal conductivity, and rigidity of the composite material.
Article
Engineering, Mechanical
Seunghwa Yang, Hyunseong Shin, Maenghyo Cho
Summary: This study presents positive contributions of oxygen functional groups in single-layer graphene oxide to the mechanical and interfacial properties of polyethylene/graphene nanocomposites, with the potential for improving the longitudinal shear modulus while degrading the longitudinal Young's and in-plane shear moduli. The interphase zone and interfacial stiffening effect are confirmed to contribute to the elasticity of nanocomposites, and a novel evolution of out-of-plane normal stress and longitudinal shear stress in single-layer GO is demonstrated through atomic virial stress interaction with the surrounding PE matrix.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Chemistry, Physical
Yanjun Zhang, Mostafa Hooman, Indrajit Patra, T. Ch. Anil Kumar, Hasan Sh. Majdi, Samar Emad Izzat, R. Sivaraman, Davood Toghraie, Maboud Hekmatifar, Roozbeh Sabetvand
Summary: The mechanical behavior of Pt-graphene nanocomposites was investigated using molecular dynamics simulation. The study found that increasing the number of graphene nanosheets improved the mechanical strength of the sample, while increasing the graphene atomic ratio and porosity decreased the mechanical performance.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
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
Chemistry, Physical
Yipeng Zhou, Yixin Ouyang, Yehui Zhang, Qiang Li, Jinlan Wang
Summary: This Perspective article summarizes the recent progress and achievements in simulating electrochemical interfaces using machine learning. It discusses the limitations of current machine learning models, such as accurately describing long-range electrostatic interactions and the kinetics of electrochemical reactions at the interface. Finally, it points out future directions for machine learning to expand in the field of electrochemical interfaces.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Takashi Kojima, Takashi Washio, Satoshi Hara, Masataka Koishi
Summary: This study proposes a novel and effective three-step search method for efficiently sampling filler morphologies in a high-dimensional parameter space, leading to the induction of extremely high modulus. The efficiency of the proposed method is demonstrated through comparison with random sampling.
COMPUTATIONAL MATERIALS SCIENCE
(2022)
Article
Nanoscience & Nanotechnology
Settasit Chaikasetsin, Jun Young Jung, Hongdeok Kim, Brian S. Y. Kim, Jungju Seo, Joonmyung Choi, Kiho Bae, Woosung Park
Summary: In this study, a novel method is developed to directly probe the thermal expansion of nanoscale polymer films using an atomic force microscope and confining active thermal volume. It is found that the in-plane thermal expansion of the spin-coated poly-(methyl methacrylate) is enhanced by 20-fold compared to the out-of-plane expansion in confined dimensions. Molecular dynamics simulations show that the collective motion of side groups along backbone chains uniquely drives the enhancement of thermal expansion anisotropy in nanoscale polymers. This work unveils the intimate role of microstructure in the thermal-mechanical interaction of polymer films, paving a way to enhance the reliability of thin-film devices.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Materials Science, Multidisciplinary
Youngoh Kim, Joonmyung Choi
Summary: In the design and manufacturing of ultra-fine grained materials, the competitive relationship between grain growth and intergranular bonding under thermal loads is crucial. This study investigated the initiation of load transfer through the glassy disordered phase during the binding of Y2O3 nanoparticles. The analysis showed that yttrium cations and oxygen anions play opposing mechanical roles within the disordered phase.
Article
Chemistry, Physical
Byeonghwa Goh, Joonmyung Choi
Summary: The microscopic structural changes of coiled multi-walled carbon nanotube (MWCNT) yarns during mechanical deformation are investigated using a multiscale constitutive model. Molecular dynamics simulations reveal that the nanotube diameter significantly affects the nonlinear mechanical behavior. The multiscale modeling predicts the stress and interstitial area change for each nanotube based on its diameter and position distribution in the microstructure.
Article
Engineering, Manufacturing
Hongdeok Kim, Joonmyung Choi
Summary: This study focuses on the effect of order-to-disorder phase transition on the mechanical properties of nanocomposites using classical molecular dynamics (MD) simulations. The results suggest that long-range p-p stacking of the aromatic rings on the nanotube surface is the key to maintaining mechanical stability under thermal loads. The morphological consistency of the interfacial LCP allows the microstructure to preserve high load transfer efficiency even after experiencing high temperatures, improving the mechanical performance of nanocomposites.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2023)
Article
Physics, Applied
Jungmin Ko, Jinkyu Bae, Minho Park, Younghyun Jo, Hyunjae Lee, Kyunghyun Kim, Suyoung Yoo, Sang Ki Nam, Dougyong Sung, Byungjo Kim
Summary: As semiconductor device structures become more complex and sophisticated, achieving finer and deeper patterns requires extensive engineering effort and process optimization. In this study, a process design framework combining deep learning with plasma simulations was proposed to efficiently search for optimal process conditions. The performance of the deep learning model was confirmed and it successfully provided a reasonable interpretation of plasma features and correlated well with experimental observations. The computational framework reduced trial-and-error repetitions and served as an effective tool to narrow the processing window in advanced equipment and processes.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Engineering, Civil
Byeonghwa Goh, Joonmyung Choi
Summary: This study developed a multilevel scalable spatial-coarsening method for diamond structures to selectively scale the space represented by the particles. The bonding relationship between the particles of different spatial regions was explained by the combination of the potential energies dominating each side. The proposed method accurately reproduces the tensor properties of diamond crystal material and successfully predicts the all-atom model and experimental results.
THIN-WALLED STRUCTURES
(2023)
Article
Chemistry, Physical
Seo Won Song, Hongdeok Kim, Seoyoon Shin, Seongjin Jang, Jong Hyuk Bae, Changhyun Pang, Joonmyung Choi, Ki Ro Yoon
Summary: Flexible zinc-air batteries with gel polymer electrolyte (GPE) are considered promising for next-generation wearable devices due to their high energy density, low cost, safety, and environmental friendliness. However, the evaporation of liquid component in GPE significantly reduces battery performance and lifespan. To address this issue, a hierarchically porous PVA/PAA hybrid GPE is developed, which improves electrolyte uptake and retention properties, and enhances ionic conductivity. The hybrid GPE demonstrated excellent cycling stability, rate characteristics, and power output in zinc-air batteries, showing their feasibility for powering wearable smart watches.
ENERGY STORAGE MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Chae-Lin Park, Byeonghwa Goh, Shi Hyeong Kim, Joonmyung Choi
Summary: This report introduces a spherical fleece made of wool fibers and single-walled carbon nanotubes (SWCNTs), which can generate repetitive electrical currents in all directions. The fleece can change the surface area available for ions to access SWCNTs, leading to a piezoionic phenomenon. The fabricated SWCNT/wool energy harvester has the highest current per input mechanical stress among all reported underwater mechanical energy harvesters to date, and it is suitable for low-frequency environments, making it ideal for utilizing natural forces as harvesting sources.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Engineering, Environmental
Dawoon Lee, Gaeun Park, Youngoh Kim, Joonmyung Choi, U. Hyeok Choi, Jaekyun Kim
Summary: This study proposes the optimization of the molecular-level tailoring of ionic gel polymer electrolyte (IGPE) and graphene-based electrodes to significantly improve and sustain the electrochemical performance of all-solid-state electrochemical energy storage (EES) devices. The optimized EES microsupercapacitor (MSC) device exhibits excellent mechanical flexibility and environmental stability, making it a promising candidate for powering wearable electronics. Molecular-level simulation and spectroscopic atomic analysis reveal lower residual ionic liquid molecules in the optimized device.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Polymer Science
Yeongbin Kim, Hongdeok Kim, Joonmyung Choi
Summary: The mechanical principle of microstructural change governing the shape formation and restoration process of shape memory epoxy (SME) was analyzed on a subcontinuum scale. Molecular dynamics simulations were used to implement a series of processes to program and operate the microstructure of highly crosslinked networks, revealing the mechanisms by which the chemical composition and topology of the network determine the shape memory behavior. Classifying the molecules into different categories based on classical kinematic framework effectively clarified the structure-property relationship. The results showed that the shape programming process rearranged the molecular components, resulting in local residual stresses, and the subsequent thermal load led to shape recovery by removing residual stress and changing the mechanical anisotropy of the entire system.
EUROPEAN POLYMER JOURNAL
(2023)
Article
Polymer Science
Youngoh Kim, Joonmyung Choi
Summary: This study investigates the modulation of polyhedral oligomeric silsesquioxanes (POSSs) on the thermal stability of polymer nanocomposites with inorganic fillers. It reveals that the low-frequency vibration of POSS and the dual frequency of the C-Si stretching mode play crucial roles in enhancing the nanocomposite's thermal stability. The ability of inorganic fillers to block exothermic reaction pathways under high-temperature conditions is also identified. These findings provide insights into the perturbation mechanism of inorganic fillers on the thermodynamics and thermochemistry of polymer matrices.
POLYMER DEGRADATION AND STABILITY
(2023)
Article
Engineering, Mechanical
Minseok Kang, Hyunkoo Lee, Sukjoon Hong, Joonmyung Choi
Summary: The thermal conduction properties of a cross-junction formed by a pair of Ag nanowires were characterized using experiments and simulations. Laser-sintering and molecular dynamics simulations were employed to investigate the heat flow trajectory and energy transfer behavior at the junctions. The results showed the stability of the interface junction, convergence of heat flux, and the relationship between nanoscale geometry and thermal conductivity.
EXTREME MECHANICS LETTERS
(2023)
Article
Chemistry, Physical
Youngoh Kim, Joonmyung Choi
Summary: Based on theoretical multiscale analysis, this study investigates the electromechanical origin of anisotropic thermal conduction in Ti3C2O2M (M = Li, Na, K), a 2D layered nanomaterial. The results reveal that acoustic and optical phonon modes drive interlayer and intralayer heat conduction, respectively. The faster response of the alkali ion layer to external oscillations is observed with lower atomic number of the ions, owing to their low inertia and high electrostatic force. The Li-ion layer exhibits instantaneous response to vibrational excitations, making it transparent to higher phonon modes.
Article
Chemistry, Physical
Hyun-Wook Lee, Youngoh Kim, Joo-Eun Kim, Ja-Yeong Kim, Jae-Yeon Jang, Joonmyung Choi, Won-Jin Kwak
Summary: This study introduces diluted electrolytes as non-solvating electrolytes to prevent the dissolution of organic electrodes in lithium-ion batteries. The use of a diluted electrolyte significantly improves the capacity retention and rate performance of the organic electrode, as demonstrated by electrochemical and spectroscopic measurements and molecular dynamics simulations. This study presents a promising strategy for achieving highly reversible organic electrode-based LIBs through the development of nonsolvating electrolytes.
ADVANCED ENERGY MATERIALS
(2023)
Article
Engineering, Manufacturing
Hongdeok Kim, Joonmyung Choi
Summary: This study investigates the phase transition and mechanical behavior at the ALCP/CNT interface under heat and light stimulation using molecular dynamics simulations. The results suggest that the strong interaction between the azobenzene and CNT directly affects the mechanical behavior due to high interfacial stability. The unique stacking and alignment properties of the interfacial azobenzene with CNTs contribute to its stability.
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
(2023)
Article
Polymer Science
Yuanzhang Jiang, Xuyi Wang, Yanting Han, Dakai Gong, Yingchun Gu, Lin Tan
Summary: In this study, FeCl3 and poly(acrylic acid) (PAA) were doped into waterborne polyurethanes (WPUs) to create multifunctional materials with self-healing and antimicrobial properties. WPU/Fe/PAA-5.5, containing 5.5 wt % PAA, exhibited excellent mechanical properties, strong self-healing capabilities, and an impressive antimicrobial rate of over 90%. These supramolecular films were also highly recyclable through hot-pressing.
Article
Polymer Science
Longyu Tian, Min Wang, Guangming Liao, Baoliang Liu, Sujuan Zhang, Yucheng Sun, Zhen Meng, Jintao Zhang, Zaijun Lu
Summary: Two kinds of benzoxazine monomers were synthesized and used to prepare polybenzoxazine anion exchange membranes (AEMs) with quaternary ammonium functionalization. The LQPBZ AEM exhibited better ion conductivity and alkaline stability.
Article
Polymer Science
Claire A. Lemarchand
Summary: This study investigates the shock behavior of three different polymers through molecular dynamics simulations. The results reveal specificities in the shock behavior of polymers, including deviations from the linear relation between shock velocity and particle velocity, as well as differences in shear stress relaxation behind the shock front. It is found that the deviation of the Hugoniot locus is related to the change in the relative contribution of bonding and non-bonding potential energies, while polymers with higher glass transition temperatures exhibit slower shear stress relaxation.
Article
Polymer Science
Zengquan Liu, Xiaochun Yin, He Zhang, Shuo Gao, Qinglin Kuang, Yanhong Feng
Summary: A powder solid-state extension (PSSE) technology was proposed to address the high melt viscosity issue of UHMWPE. By uniaxial extension and sintering in the solid state, a highly self-reinforced material was prepared. X-ray diffraction and scattering techniques were used to study the structural evolution during the PSSE process, and a solid-phase induced transformation model was established.
Article
Polymer Science
Zhike Li, Anyu Luo, Rui Zhou, Xin Li, Haiyan Li
Summary: A novel high temperature resistance IL@SiO2 nanocapsules were successfully prepared and their friction and wear properties in PA6 composites were studied. The addition of IL@SiO2 nanocapsules reduced the friction coefficient and wear rate without affecting the mechanical properties of PA6. The synergy between the IL core and SiO2 wall in the nanocapsules improved the self-lubricating performance of the PA6 composites.
Article
Polymer Science
Xin Liu, Xuhong Guo, Qi Liao
Summary: In this study, an algorithm for accurately estimating viscosity is developed using molecular dynamics simulations and the Green-Kubo formula. This algorithm can be applied to complex systems with long correlations, such as macromolecular and biological simulation systems.
Article
Polymer Science
Hao Pu, Yun-Lei Hou, Jing -Zhou Chen, Dong -Lin Zhao
Summary: The use of modified graphene improves the interfacial adherence of carbon fibers to epoxy resin, resulting in enhanced interfacial and bending properties of CF and matrix in CF/EP composites, as well as increased interlaminar shear strength and flexural strength.
Article
Polymer Science
Wei-Chung Ke, Jin-Wei Lin, Manohar Reddy Busireddy, Yueh-Hsing Lee, Jiun-Tai Chen, Chain-Shu Hsu
Summary: This study introduces a crosslinkable monomer, TAIC, to synthesize three crosslinked polyimide films, which exhibit improved thermal, mechanical, and dielectric properties. The introduction of TAIC enhances the tensile strength, reduces the dielectric constant and dielectric loss, and decreases the coefficient of thermal expansion of the polyimide films.
Article
Polymer Science
Alex Kwasi Kumi, Ruiling Fan, Ye Chen, Yumei Zhang
Summary: The difference in leaching of amylopectin from cellulose/amylopectin/1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) blends during regeneration in water and aqueous ethanol has been studied. Molecular dynamics simulations showed that the dissolution and regeneration mechanisms of amylopectin in [Bmim][Cl] are similar to cellulose in ionic liquids. Water regeneration leads to weak electrostatic interactions, resulting in high leaching of amylopectin. In contrast, ethanol-water interactions enhance electrostatic interactions among amylopectin chains, limiting amylopectin leaching in aqueous ethanol.
Article
Polymer Science
Xi Zeng, Junwei Zhou, Junbiao Peng, Chunsheng Zhang, Danling Wang, Yihu Song, Qiang Zheng
Summary: This study utilizes an oligomer deep eutectic solvent (DES) based on polyethylene glycol to regulate the vulcanization kinetics of rubber. The results show that the DES can accelerate vulcanization at low temperatures without affecting the crosslinking density and Mullins effect.
Article
Polymer Science
Qianqian Yue, Yongfei Peng, Xingjian Liu, Aihua He, Huarong Nie
Summary: The addition of metal deactivators can effectively suppress the aging of TBIR, prolong its lifespan, and have no negative effects on its physical and processing properties. These research findings are of great importance for improving the stability and aging resistance of polymers.
Article
Polymer Science
J. Gomez-Caturla, J. Ivorra-Martinez, R. Tejada-Oliveros, V Moreno, D. Garcia-Garcia, R. Balart
Summary: This work focuses on the development of environmentally friendly PLA formulations by using different esters derived from geraniol as plasticizers. The results show that these esters have good compatibility with PLA, and they can effectively enhance the elongation and plasticity of PLA, reduce its glass transition temperature, and slightly improve its water absorption capabilities.
Article
Polymer Science
Dandan Li, Zhaohui Lu, Zhao Ke, Ke Xu, Fengna Dai, Youhai Yu, Guangtao Qian, Chunhai Chen
Summary: In this study, cross-linked PI aerogel membranes with low dielectric constant and high moisture resistance were prepared by co-polymerization and scraping coating technology. The incorporation of fluorinated blocks and benzimidazole ring structures resulted in novel PI aerogel membranes with fascinating dielectric properties and outstanding moisture resistance.
Article
Polymer Science
Zhaoyang Chu, Qing Zhang, Haihua Luo, Han Zhou, Fapei Zhang, Wei Chen, Wenhua Zhang
Summary: Multi-physical fields solution processing strategy is a universal and facile method for preparing various conjugated polymer films and high-performance devices. In this study, we employed a combined microfluidic flow and ultrasonication strategy (FU) for processing CP solutions, and found a pronounced synergetic effect in promoting the pre-ordering of chains in solution. The conformation order and anisotropy of the solution were revealed through various characterizations. A non-classical nucleation model for polymer crystallization in non-equilibrium solution processing was confirmed. The roles of microfluidic flow and ultrasonication in chain aggregation and crystallization were addressed through multi-physical simulations. Compared to pristine solutions, the FU strategy showed improved solution anisotropy and crystallization kinetics, resulting in higher crystallinity in films and increased mobilities in OFET devices. The FU processing strategy provides a universal approach for regulating chain conformation and aggregation in conjugated polymer solutions.
