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Romero Garcia S, Zholdassov YS, Braunschweig AB, Martini A. Reactive Simulations of Silica Functionalization with Aromatic Hydrocarbons. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:561-567. [PMID: 38112539 DOI: 10.1021/acs.langmuir.3c02785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Reactive molecular dynamics simulations are used to model the covalent functionalization of amorphous silica with aromatic hydrocarbons. Simulations show that the surface density of silanol-terminated phenyl, naphthyl, and anthracenyl molecules is lower than the maximum value calculated based on molecule geometry, and the simulation densities decrease faster with the number of aromatic rings than the geometric densities. The trends are analyzed in terms of the surface-silanol bonding configurations, tilt angles, local conformational ordering, and aggregation of surface-bound molecules under steady-state conditions. Results show that the surface density is affected by both the size and symmetry of the aromatic hydrocarbons. The correlations among bonding, orientation, and surface density identified here may guide the selection or design of molecules for functionalized surfaces.
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Affiliation(s)
- Sergio Romero Garcia
- Department of Materials and Biomaterials Science and Engineering, University of California Merced, 5200 N. Lake Road, Merced, California 95343, United States
| | - Yerzhan S Zholdassov
- The Advanced Science Research Center at the Graduate Center of the City University of New York, 85 St. Nicholas Terrace, New York, New York 10031, United States
- Department of Chemistry, Hunter College, 695 Park Avenue, New York, New York 10065, United States
- The Ph.D. Program in Chemistry, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
| | - Adam B Braunschweig
- The Advanced Science Research Center at the Graduate Center of the City University of New York, 85 St. Nicholas Terrace, New York, New York 10031, United States
- Department of Chemistry, Hunter College, 695 Park Avenue, New York, New York 10065, United States
- The Ph.D. Program in Chemistry, Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
| | - Ashlie Martini
- Department of Mechanical Engineering, University of California Merced, 5200 N. Lake Road, Merced, California 95343, United States
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Li Z, Shen K, Hu M, Shulga YM, Chen Z, Liu Q, Li M, Wu X. Heat-Treated Aramid Pulp/Silica Aerogel Composites with Improved Thermal Stability and Thermal Insulation. Gels 2023; 9:749. [PMID: 37754430 PMCID: PMC10530268 DOI: 10.3390/gels9090749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/09/2023] [Accepted: 09/12/2023] [Indexed: 09/28/2023] Open
Abstract
In this work, we prepared heat-treated aramid pulp/silica aerogel composites (AP/aerogels) and investigated in detail the feasibility of improving thermal stability and thermal insulation via tailored heat treatment. The microstructure and FTIR spectra reveal that AP/aerogels are formed by a physical combination of the silica aerogel matrix and aramid pulps. When the heat treatment temperature increases, the density slightly decreases and then increases to the maximum due to the significant volume shrinkage. The pyrolysis of aramid pulp and the collapse of silica skeletons occur during heat treatment; nevertheless, the typical structures of AP/aerogels do not change significantly. It is also found that both the hydrophobicity and the thermal insulation decrease with the increasing heat treatment temperature. We note that when the heat treatment is at 600 °C, the AP/aerogel still maintains a low density of 0.19 g/cm3 and a contact angle of 138.5°. The thermal conductivity is as low as 26.11 mW/m/K, measured using the transient hot wire method. Furthermore, the heat-treated AP/aerogels can avoid heat shock and possible thermal hazards during practical thermal insulation applications. The onset temperatures of the thermal decomposition of AP/aerogels increase from 298.8 °C for an untreated one to 414.7 °C for one treated at 600 °C, indicating that the thermal stability of AP/aerogels is improved significantly. This work provides a practical engineering approach to expand the thermal insulation applications of silica aerogel composites.
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Affiliation(s)
- Zhi Li
- School of Resources and Safety Engineering, Central South University, Changsha 410083, China
| | - Kai Shen
- School of Resources and Safety Engineering, Central South University, Changsha 410083, China
| | - Min Hu
- School of Resources and Safety Engineering, Central South University, Changsha 410083, China
| | - Yury M. Shulga
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Academician Semenov Avenue 1, Chernogolovka, 142432 Moscow, Russia
| | - Zhenkui Chen
- Department of Engineering Technology and Application, The Army Infantry College of PLA, Nanchang 330103, China
| | - Qiong Liu
- School of Resources and Safety Engineering, Central South University, Changsha 410083, China
| | - Ming Li
- School of Resources and Safety Engineering, Central South University, Changsha 410083, China
| | - Xiaoxu Wu
- School of Resources and Safety Engineering, Central South University, Changsha 410083, China
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Li T, Dufresne ER, Kröger M, Heyden S. Siloxane Molecules: Nonlinear Elastic Behavior and Fracture Characteristics. Macromolecules 2023; 56:1303-1310. [PMID: 36874533 PMCID: PMC9979691 DOI: 10.1021/acs.macromol.2c02576] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/17/2023] [Indexed: 02/10/2023]
Abstract
Fracture phenomena in soft materials span multiple length and time scales. This poses a major challenge in computational modeling and predictive materials design. To pass quantitatively from molecular to continuum scales, a precise representation of the material response at the molecular level is vital. Here, we derive the nonlinear elastic response and fracture characteristics of individual siloxane molecules using molecular dynamics (MD) studies. For short chains, we find deviations from classical scalings for both the effective stiffness and mean chain rupture times. A simple model of a nonuniform chain of Kuhn segments captures the observed effect and agrees well with MD data. We find that the dominating fracture mechanism depends on the applied force scale in a nonmonotonic fashion. This analysis suggests that common polydimethylsiloxane (PDMS) networks fail at cross-linking points. Our results can be readily lumped into coarse-grained models. Although focusing on PDMS as a model system, our study presents a general procedure to pass beyond the window of accessible rupture times in MD studies employing mean first passage time theory, which can be exploited for arbitrary molecular systems.
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Affiliation(s)
- Tianchi Li
- Soft and Living Materials, Department of Materials, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Eric R Dufresne
- Soft and Living Materials, Department of Materials, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Martin Kröger
- Polymer Physics, Department of Materials, ETH Zurich, CH-8093 Zurich, Switzerland.,Magnetism and Interface Physics, Department of Materials, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Stefanie Heyden
- Soft and Living Materials, Department of Materials, ETH Zurich, CH-8093 Zurich, Switzerland
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Muthukumaran T, Philip J. A facile approach to synthesis of cobalt ferrite nanoparticles with a uniform ultrathin layer of silicon carbide for organic dye removal. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.114110] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Study on cellulose degradation induced by hydroxyl radical with cellobiose as a model using GC–MS, ReaxFF simulation and DFT computation. Carbohydr Polym 2020; 233:115677. [DOI: 10.1016/j.carbpol.2019.115677] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 11/10/2019] [Accepted: 11/25/2019] [Indexed: 12/30/2022]
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Milne ZB, Schall JD, Jacobs TDB, Harrison JA, Carpick RW. Covalent Bonding and Atomic-Level Plasticity Increase Adhesion in Silicon-Diamond Nanocontacts. ACS APPLIED MATERIALS & INTERFACES 2019; 11:40734-40748. [PMID: 31498997 DOI: 10.1021/acsami.9b08695] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nanoindentation and sliding experiments using single-crystal silicon atomic force microscope probes in contact with diamond substrates in vacuum were carried out in situ with a transmission electron microscope (TEM). After sliding, the experimentally measured works of adhesion were significantly larger than values estimated for pure van der Waals (vdW) interactions. Furthermore, the works of adhesion increased with both the normal stress and speed during the sliding, indicating that applied stress played a central role in the reactivity of the interface. Complementary molecular dynamics (MD) simulations were used to lend insight into the atomic-level processes that occur during these experiments. Simulations using crystalline silicon tips with varying degrees of roughness and diamond substrates with different amounts of hydrogen termination demonstrated two relevant phenomena. First, covalent bonds formed across the interface, where the number of bonds formed was affected by the hydrogen termination of the substrate, the tip roughness, the applied stress, and the stochastic nature of bond formation. Second, for initially rough tips, the sliding motion and the associated application of shear stress produced an increase in irreversible atomic-scale plasticity that tended to smoothen the tips' surfaces, which resulted in a concomitant increase in adhesion. In contrast, for initially smooth tips, sliding roughened some of these tips. In the limit of low applied stress, the experimentally determined works of adhesion match the intrinsic (van der Waals) work of adhesion for an atomically smooth silicon-diamond interface obtained from MD simulations. The results provide mechanistic interpretations of sliding-induced changes and interfacial adhesion and may help inform applications involving adhesive interfaces that are subject to applied shear forces and displacements.
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Affiliation(s)
- Zachary B Milne
- Department of Mechanical Engineering and Applied Mechanics , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
| | - J David Schall
- Mechanical Engineering Department , North Carolina Agricultural and Technical State University , Greensboro , North Carolina 27411 , United States
| | - Tevis D B Jacobs
- Department of Mechanical Engineering and Materials Science , University of Pittsburgh , Pittsburgh , Pennsylvania 15261 , United States
| | - Judith A Harrison
- Chemistry Department , United States Naval Academy Annapolis , Maryland 21402 , United States
| | - Robert W Carpick
- Department of Mechanical Engineering and Applied Mechanics , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States
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Barcaro G, Carravetta V, Sementa L, Monti S. Reactive force field simulations of silicon clusters. ADVANCES IN PHYSICS: X 2019. [DOI: 10.1080/23746149.2019.1634487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Affiliation(s)
- Giovanni Barcaro
- CNR-IPCF, Institute of Chemical and Physical Processes, Pisa, Italy
| | | | - Luca Sementa
- CNR-IPCF, Institute of Chemical and Physical Processes, Pisa, Italy
| | - Susanna Monti
- CNR-ICCOM, Institute of Chemistry of Organometallic Compounds, Pisa, Italy
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Pujari S, Filippov AD, Gangarapu S, Zuilhof H. High-Density Modification of H-Terminated Si(111) Surfaces Using Short-Chain Alkynes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:14599-14607. [PMID: 29240433 PMCID: PMC6150740 DOI: 10.1021/acs.langmuir.7b03683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 11/29/2017] [Indexed: 05/31/2023]
Abstract
H-Si(111)-terminated surfaces were alkenylated via two routes: through a novel one-step gas-phase hydrosilylation reaction with short alkynes (C3 to C6) and for comparison via a two-step chlorination and Grignard alkenylation process. All modified surfaces were characterized by static water contact angles and X-ray photoelectron spectroscopy (XPS). Propenyl- and butenyl-coated Si(111) surfaces display a significantly higher packing density than conventional C10-C18 alkyne-derived monolayers, showing the potential of this approach. In addition, propyne chemisorption proceeds via either of two approaches: the standard hydrosilylation at the terminal carbon (lin) at temperatures above 90 °C and an unprecedented reaction at the second carbon (iso) at temperatures below 90 °C. Molecular modeling revealed that the packing energy of a monolayer bonded at the second carbon is significantly more favorable, which drives iso-attachment, with a dense packing of surface-bound iso-propenyl chains at 40% surface coverage, in line with the experiments at <90 °C. The highest density monolayers are obtained at 130 °C and show a linear attachment of 1-propenyl chains with 92% surface coverage.
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Affiliation(s)
- Sidharam
P. Pujari
- Laboratory
of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Alexei D. Filippov
- Laboratory
of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Satesh Gangarapu
- Laboratory
of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Han Zuilhof
- Laboratory
of Organic Chemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
- School
of Pharmaceutical Sciences and Technology, Tianjin University, 92 Weijin Road, Tianjin, People’s
Republic of China
- Department
of Chemical and Materials Engineering, King
Abdulaziz University, Jeddah, Saudi Arabia
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