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Moussavi A, Pal S, Wu Z, Keten S. Characterizing the shear response of polymer-grafted nanoparticles. J Chem Phys 2024; 160:134903. [PMID: 38573850 DOI: 10.1063/5.0188494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 03/18/2024] [Indexed: 04/06/2024] Open
Abstract
Grafting polymer chains to the surface of nanoparticles overcomes the challenge of nanoparticle dispersion within nanocomposites and establishes high-volume fractions that are found to enable enhanced material mechanical properties. This study utilizes coarse-grained molecular dynamics simulations to quantify how the shear modulus of polymer-grafted nanoparticle (PGN) systems in their glassy state depends on parameters such as strain rate, nanoparticle size, grafting density, and chain length. The results are interpreted through further analysis of the dynamics of chain conformations and volume fraction arguments. The volume fraction of nanoparticles is found to be the most influential variable in deciding the shear modulus of PGN systems. A simple rule of mixture is utilized to express the monotonic dependence of shear modulus on the volume fraction of nanoparticles. Due to the reinforcing effect of nanoparticles, shortening the grafted chains results in a higher shear modulus in PGNs, which is not seen in linear systems. These results offer timely insight into calibrating molecular design parameters for achieving the desired mechanical properties in PGNs.
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Affiliation(s)
- Arman Moussavi
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Subhadeep Pal
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Zhenghao Wu
- Department of Chemistry, Xi'an Jiaotong Liverpool University, Suzhou, People's Republic of China
| | - Sinan Keten
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, Illinois 60208, USA
- Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, USA
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2
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Elliott JP, Osti NC, Tyagi M, Mamontov E, Liu L, Serrano JM, Cao K, Liu G. Exceptionally Fast Ion Diffusion in Block Copolymer-Based Porous Carbon Fibers. ACS APPLIED MATERIALS & INTERFACES 2022; 14:36980-36986. [PMID: 35916606 DOI: 10.1021/acsami.2c12755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Confined ionic liquids in hydrophilic porous media have disrupted lattices and can be divided into two layers: An immobile ion layer adheres to the pore surfaces, and an inner layer exhibits faster mobility than the bulk. In this work, we report the first study of ionic liquids confined in block copolymer-based porous carbon fibers (PCFs) synthesized from polyacrylonitrile-block-polymethyl methacrylate (PAN-b-PMMA). The PCFs contain a network of unimodal mesopores of 13.6 nm in diameter and contain more hydrophilic surface functional groups than previously studied porous carbon. Elastic neutron scattering shows no freezing point for 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) confined in PCFs down to 20 K. Quasi-elastic neutron scattering (QENS) is used to measure the diffusion of [BMIM]BF4 confined in PCFs, which, surprisingly, is 7-fold faster than in the bulk. The unprecedentedly high ion diffusion remarks that PCFs hold exceptional potential for use in electrochemical catalysis, energy conversion, and storage.
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Affiliation(s)
- John P Elliott
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Naresh C Osti
- Neutron Scattering Division, Oak Ridge National Laboratory, P.O. Box 2008 MS6455, Oak Ridge, Tennessee 37831, United States
| | - Madhusudan Tyagi
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, United States
| | - Eugene Mamontov
- Neutron Scattering Division, Oak Ridge National Laboratory, P.O. Box 2008 MS6455, Oak Ridge, Tennessee 37831, United States
| | - Lifeng Liu
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-330 Braga, Portugal
| | - Joel M Serrano
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Ke Cao
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Guoliang Liu
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States
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3
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Wang A, Vargas-Lara F, Younker JM, Iyer KA, Shull KR, Keten S. Quantifying Chemical Composition and Cross-link Effects on EPDM Elastomer Viscoelasticity with Molecular Dynamics. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00162] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Jarod M. Younker
- ExxonMobil Chemical Company, Baytown, Texas 77520, United States
| | - Krishnan A. Iyer
- ExxonMobil Chemical Company, Baytown, Texas 77520, United States
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Frieberg BR, Glynos E, Sakellariou G, Tyagi M, Green PF. Effect of Molecular Stiffness on the Physical Aging of Polymers. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01331] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Emmanouil Glynos
- Institute of Electronic Structure and Laser, Foundation for Research and Technology—Hellas, P.O. Box 1385, 71110 Heraklion, Crete, Greece
| | - Georgios Sakellariou
- Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis
Zografou, 15771 Athens, Greece
| | - Madhusudan Tyagi
- NIST Center for Neutron Research, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
- Department of Materials Science, University of Maryland, College Park, Maryland 20742, United States
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Elamin K, Jansson H, Swenson J. Dynamics of aqueous binary glass-formers confined in MCM-41. Phys Chem Chem Phys 2015; 17:12978-87. [PMID: 25913915 DOI: 10.1039/c5cp00751h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Dielectric permittivity measurements were performed on water solutions of propylene glycol (PG) and propylene glycol monomethyl ether (PGME) confined in 21 Å pores of the silica matrix MCM-41 C10 in wide frequency (10(-2)-10(6) Hz) and temperature (130-250 K) ranges. The aim was to elucidate how the formation of large hydrogen bonded structural entities, found in bulk solutions of PGME, was affected by the confined geometry, and to make comparisons with the dynamic behavior of the PG-water system. For all solutions the measurements revealed four almost concentration independent relaxation processes. The intensity of the fastest process is low compared to the other relaxation processes and might be caused by both hydroxyl groups of the pore surfaces and by local motions of water and solute molecules. The second fastest process contains contributions from both the main water relaxation as well as the intrinsic β-relaxation of the solute molecules. The third fastest process is the viscosity related α-relaxation. Its concentration independency is very different compared to the findings for the corresponding bulk systems, particularly for the PGME-water system. The experimental data suggests that the surface interactions induce a micro-phase separation of the two liquids, resulting in a full molecular layer of water molecules coordinating to the hydrophilic hydroxyl groups on the surfaces of the silica pores. This, in turn, increases the geometrical confinement effect for the remaining solution even more and prevents the building up of the same type of larger structural entities in the PGME-water system as in the corresponding bulk solutions. The slowest process is mainly hidden in the high conductivity contribution at low frequencies, but its temperature dependence can be extracted for the PGME-water system. However, its origin is not fully clear, as will be discussed.
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Affiliation(s)
- Khalid Elamin
- Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
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Djemour A, Sanctuary R, Baller J. Mobility restrictions and glass transition behaviour of an epoxy resin under confinement. SOFT MATTER 2015; 11:2683-2690. [PMID: 25689879 DOI: 10.1039/c4sm02774d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Confinement can have a big influence on the dynamics of glass formers in the vicinity of the glass transition. Already 40 to 50 K above the glass transition temperature, thermal equilibration of glass formers can be strongly influenced by the confining substrate. We investigate the linear thermal expansion and the specific heat capacity cp of an epoxy resin (diglycidyl ether of bisphenol A, DGEBA) in a temperature interval of 120 K around the glass transition temperature. The epoxy resin is filled into controlled pore glasses with pore diameters between 4 and 111 nm. Since DGEBA can form H-bonds with silica surfaces, we also investigate the influence of surface silanization of the porous substrates. In untreated substrates a core/shell structure of the epoxy resin can be identified. The glass transition behaviours of the bulk phase and that of the shell phase are different. In silanized substrates, the shell phase disappears. At a temperature well above the glass transition, a second transition is found for the bulk phase - both in the linear expansion data as well as in the specific heat capacity. The cp data do not allow excluding the glass transition of a third phase as being the cause for this transition, whereas the linear expansion data do so. The additional transition temperature is interpreted as a separation between two regimes: above this temperature, macroscopic flow of the bulk phase inside the porous structure is possible to balance the mismatch of thermal expansion coefficients between DGEBA and the substrate. Below the transition temperature, this degree of freedom is hindered by geometrical constraints of the porous substrates. Moreover, this second transition could also be found in the linear expansion data of the shell phase.
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Affiliation(s)
- A Djemour
- Physics and Materials Science Research Unit, Laboratory for the Physics of Advanced Materials, University of Luxembourg, 162A, avenue de la Faïencerie, L-1511 Luxembourg, Grand-Duchy of Luxembourg.
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Molecular Order and Dynamics of Tris(2-ethylhexyl)phosphate Confined in Uni-Directional Nanopores. Z PHYS CHEM 2012. [DOI: 10.1524/zpch.2012.0287] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
Infrared Transition Moment Orientational Analysis (IR–TMOA) and Broadband Dielectric Spectroscopy (BDS) are combined to study molecular order and dynamics of the glass-forming liquid Tris(2-ethylhexy)phosphate (TEHP) confined in uni-directional nanopores with diameters of 4, 8, and 10.4 nm. The former method enables one to determine the molecular order parameter of specific IR transition moments. It is observed that the central P=O moiety of TEHP has a weak orientational effect (molecular order parameter S
z
= −0.1 ± 0.04) due the nanoporous confinement, in contrast to the terminal C–H groups. BDS traces the dynamic glass transition of the guest molecules in a broad spectral range and at widely varying temperature. An enhancement of the mobility takes place when approaching the glass transition temperature and becomes more pronounced with decreasing pore diameter. This is attributed to a slight reduction of the density of the confined liquid caused by the 2-dimensional geometrical constraint.
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Qian KK, Bogner RH. Application of Mesoporous Silicon Dioxide and Silicate in Oral Amorphous Drug Delivery Systems. J Pharm Sci 2012; 101:444-63. [DOI: 10.1002/jps.22779] [Citation(s) in RCA: 156] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 09/06/2011] [Accepted: 09/15/2011] [Indexed: 11/08/2022]
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