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Ogbomo E, Bhuiyan FH, Latorre CA, Martini A, Ewen JP. Effects of surface chemistry on the mechanochemical decomposition of tricresyl phosphate. Phys Chem Chem Phys 2023; 26:278-292. [PMID: 38059507 DOI: 10.1039/d3cp05320b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
The growth of protective tribofilms from lubricant antiwear additives on rubbing surfaces is initiated by mechanochemically promoted dissociation reactions. These processes are not well understood at the molecular scale for many important additives, such as tricresyl phosphate (TCP). One aspect that needs further clarification is the extent to which the surface properties affect the mechanochemical decomposition. Here, we use nonequilibrium molecular dynamics (NEMD) simulations with a reactive force field (ReaxFF) to study the decomposition of TCP molecules confined and pressurised between sliding ferrous surfaces at a range of temperatures. We compare the decomposition of TCP on native iron, iron carbide, and iron oxide surfaces. We show that the decomposition rate of TCP molecules on all the surfaces increases exponentially with temperature and shear stress, implying that this is a stress-augmented thermally activated (SATA) process. The presence of base oil molecules in the NEMD simulations decreases the shear stress, which in turn reduces the rate constant for TCP decomposition. The decomposition is much faster on iron surfaces than iron carbide, and particularly iron oxide. The activation energy, activation volume, and pre-exponential factor from the Bell model are similar on iron and iron carbide surfaces, but significantly differ for iron oxide surfaces. These findings provide new insights into the mechanochemical decomposition of TCP and have important implications for the design of novel lubricant additives for use in high-temperature and high-pressure environments.
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Affiliation(s)
- Egheosa Ogbomo
- Department of Mechanical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, London, UK.
- Institute of Molecular Science and Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, London, UK
- The Thomas Young Centre, Imperial College London, South Kensington Campus, SW7 2AZ, London, UK
| | - Fakhrul H Bhuiyan
- Department of Mechanical Engineering, University of California-Merced, 5200 N. Lake Road, Merced 95343, CA, USA
| | - Carlos Ayestarán Latorre
- Department of Mechanical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, London, UK.
- Institute of Molecular Science and Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, London, UK
- The Thomas Young Centre, Imperial College London, South Kensington Campus, SW7 2AZ, London, UK
| | - Ashlie Martini
- Department of Mechanical Engineering, University of California-Merced, 5200 N. Lake Road, Merced 95343, CA, USA
| | - James P Ewen
- Department of Mechanical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, London, UK.
- Institute of Molecular Science and Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, London, UK
- The Thomas Young Centre, Imperial College London, South Kensington Campus, SW7 2AZ, London, UK
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Yasuraoka K, Kaneko S, Kobayashi S, Tsukagoshi K, Nishino T. Surface-Enhanced Raman Scattering Stimulated by Strong Metal-Molecule Interactions in a C 60 Single-Molecule Junction. ACS APPLIED MATERIALS & INTERFACES 2021; 13:51602-51607. [PMID: 34695353 DOI: 10.1021/acsami.1c09965] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Specifying the geometric and electronic structures of a metal-molecule interface at the single-molecule level is crucial for the improvement of organic electronics. A single-molecule junction (SMJ) can be used to investigate interfaces because it can be regarded as an elementary unit of the interface structure. Although considerable efforts have been made to this end, the detection of structural changes in SMJs associated with metal-molecule interactions remains challenging. In this study, we detected the surface-enhanced Raman scattering (SERS) signal originating from the metal-molecule interaction change induced by a local structural change in a C60 SMJ. This junction has attracted wide attention owing to its unique electronic and vibronic properties. We fabricated a C60 SMJ using a lithographically fabricated Au electrode and measured the SERS spectra along with the current-voltage (I-V) response. By continuous measurement of SERS for the C60 SMJ, we obtained SERS spectra dependent on the local structural change. The analysis of the I-V response revealed that the vibration energy shift originates from the change in the local structure for different Au-C60 interactions. Based on the discrimination of the states in accordance with the Au-C60 interaction, we found that the probability of SERS for geometry with a large Au-C60 interaction was enhanced.
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Affiliation(s)
- Koji Yasuraoka
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Satoshi Kaneko
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8551, Japan
- JST PRESTO, 4-1-8 Honcho, Kawaguchi 332-0012, Japan
| | - Shuji Kobayashi
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Kazuhito Tsukagoshi
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Tsukuba, Ibaraki 305-0044, Japan
| | - Tomoaki Nishino
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8551, Japan
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Cao Y, Cao W, Yang X, Liu C, Qi X. Theoretical investigation of polymer molecular structure influence on dielectric properties and mechanical properties. POLYM ADVAN TECHNOL 2021. [DOI: 10.1002/pat.5499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Yuying Cao
- Institute for Frontier Materials Deakin University Geelong Victoria Australia
| | - Weihua Cao
- School of Mechanical Engineering Yanshan University Qinhuangdao China
| | - Xiao Yang
- School of Mechanical Engineering Yanshan University Qinhuangdao China
| | - Changxin Liu
- Key Laboratory of Self‐Lubricating Spherical Plain Bearing Technology of Hebei Province Yanshan University Qinhuangdao China
| | - Xiaowen Qi
- Key Laboratory of Self‐Lubricating Spherical Plain Bearing Technology of Hebei Province Yanshan University Qinhuangdao China
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Blazhynska MM, Kyrychenko A, Kalugin ON. Molecular dynamics simulation of the size-dependent morphological stability of cubic shape silver nanoparticles. MOLECULAR SIMULATION 2018. [DOI: 10.1080/08927022.2018.1469751] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
| | - Alexander Kyrychenko
- School of Chemistry, V. N. Karazin Kharkiv National University, Kharkiv, Ukraine
| | - Oleg N. Kalugin
- School of Chemistry, V. N. Karazin Kharkiv National University, Kharkiv, Ukraine
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Chen S, Li J, Wei L, Jin Y, Khosla T, Xiao J, Cheng B, Duan H. A molecular modeling study for miscibility of polyimide/polythene mixing systems with/without compatibilizer. JOURNAL OF POLYMER ENGINEERING 2018. [DOI: 10.1515/polyeng-2017-0374] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Molecular models were established to predict the miscibility of polyimide/polythene mixing systems and the enhancing effects of compatibilizer addition of maleic anhydride grafted polythene (MAH-g-PE). Molecular dynamics simulations were applied to investigate radial distribution functions and Flory-Huggins parameters of the mixing systems. Results show that polyimide/polythene is miscible to a certain degree, and the miscibility gets better after adding MAH-g-PE. Dissipative particle dynamics (DPD) simulations display that micro-phase separation occurs in the polyimide/polythene mixing systems, however, effective interfaces appear between polyimide and polythene phases after adding MAH-g-PE. The results of molecular mechanics simulations indicate that the ability of mixing systems to resist stretch, compression and shear deformation increases after adding MAH-g-PE. This work offers a promising technique to predict miscibility properties for polyimide/polythene system prior to actual production and attempt to find a suitable compatibilizer for that system.
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Affiliation(s)
- Song Chen
- State Key Laboratory of Special Surface Protection Materials and Application Technology , Wuhan Research Institute of Materials Protection , Wuhan 430030, Hubei , China
| | - Jian Li
- State Key Laboratory of Special Surface Protection Materials and Application Technology , Wuhan Research Institute of Materials Protection , Wuhan 430030, Hubei , China
| | - Lei Wei
- State Key Laboratory of Special Surface Protection Materials and Application Technology , Wuhan Research Institute of Materials Protection , Wuhan 430030, Hubei , China
| | - Yongliang Jin
- State Key Laboratory of Special Surface Protection Materials and Application Technology , Wuhan Research Institute of Materials Protection , Wuhan 430030, Hubei , China
| | - Tushar Khosla
- Business Development and Sales Department, Rtec Instruments Inc , San Jose, CA, 95131 , USA
| | - Jun Xiao
- Business Development and Sales Department, Rtec Instruments Inc , San Jose, CA, 95131 , USA
| | - Bingxue Cheng
- State Key Laboratory of Tribology , Tsinghua University , Beijing 100084 , China
| | - Haitao Duan
- State Key Laboratory of Special Surface Protection Materials and Application Technology , Wuhan Research Institute of Materials Protection , Wuhan 430030, Hubei , China
- Business Development and Sales Department, Rtec Instruments Inc , San Jose, CA, 95131 , USA
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Kyrychenko A, Pasko DA, Kalugin ON. Poly(vinyl alcohol) as a water protecting agent for silver nanoparticles: the role of polymer size and structure. Phys Chem Chem Phys 2018; 19:8742-8756. [PMID: 28217797 DOI: 10.1039/c6cp05562a] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chemical modification of silver nanoparticles (AgNPs) with a stabilizing agent, such as poly(vinyl alcohol) (PVA), plays an important role in shape-controlled seeded-growth and colloidal stability. However, theoretical aspects of the stabilizing mechanism of PVA are still poorly understood. To gain a better understanding of the role of PVA in water protecting effects for silver nanoparticles, we developed an atomistic model of a AgNP grafted with single-chain PVA of various lengths. Our model, designed for classical molecular dynamics (MD) simulations, approximates the AgNP as a quasi-spherical silver nanocrystal with 3.9 nm diameter and uses a united-atom representation for PVA with its polymer chain length varying from 220 up to 1540 repeating units. We found that PVA adsorbs onto the AgNP surface through multiple non-covalent interactions, among which non-covalent bonding of the hydroxyl groups plays a key role. The analysis of adsorption isotherms by using the Hill, Scatchard, and McGhee & von Hippel models exhibits evidence for positive binding cooperativity with the cooperativity parameter varying from 1.55 to 2.12. Our results indicate that the size of the PVA polymer rather than its structure plays a crucial role in providing water protecting effects for the AgNP core, varying from 40% up to 91%. The water-protecting efficiency was well approximated by the Langmuir-Freundlich equation, allowing us to predict that the saturated coverage of the nanoparticle of a given diameter of 3.9 nm should occur when the PVA molecular weight approaches 115 kDa, which corresponds to the number of vinyl alcohol monomers being equal to 3100 units.
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Affiliation(s)
- Alexander Kyrychenko
- Institute of Chemistry, V. N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine. and School of Chemistry, V. N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine
| | - Dmitry A Pasko
- School of Chemistry, V. N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine
| | - Oleg N Kalugin
- School of Chemistry, V. N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61022, Ukraine
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