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Alamfard T, Lorenz T, Breitkopf C. Glass Transition Temperatures and Thermal Conductivities of Polybutadiene Crosslinked with Randomly Distributed Sulfur Chains Using Molecular Dynamic Simulation. Polymers (Basel) 2024; 16:384. [PMID: 38337272 DOI: 10.3390/polym16030384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
The thermal conductivities and glass transition temperatures of polybutadiene crosslinked with randomly distributed sulfur chains having different lengths from mono-sulfur (S1) to octa-sulfur (S8) were investigated. The thermal conductivities of the related models as a function of the heat flux autocorrelation function, applying an equilibrium molecular dynamic (EMD) simulation and the Green-Kubo method, were studied for a wide range of temperatures. The influence of the length of sulfur chains, degree of crosslinking, and molar mass of the crosslinker on the glass transition temperature and final values of thermal conductivities were studied. First, the degree of crosslinking is considered constant for the eight simulation models, from mono-sulfur (S1) to octa-sulfur (S8), while the molar mass of the sulfur is increases. The results show that the thermal conductivities of the crosslinked structure decrease with increasing temperature for each model. Moreover, by increasing the lengths of the sulfur chains and the molar weight of the crosslinker, thermal conductivity increases at a constant temperature. The MD simulation demonstrates that the glass transition temperature and density of the crosslinked structure enhance as the length of the sulfur chains and molar mass of the sulfur increase. Second, the molar weight of sulfur is considered constant in these eight models; therefore, the degree of crosslinking decreases with the increase in the lengths of the sulfur chains. The results show that the thermal conductivities of the crosslinked structure decrease with the increase in the temperature for each model. Moreover, by increasing the lengths of sulfur chains and thus decreasing the degree of crosslinking, the trend in changes in thermal conductivities are almost the same for all of these models, so thermal conductivity is constant for a specific temperature. In addition, the glass transition temperature and density of the crosslinked structure decrease.
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Affiliation(s)
- Tannaz Alamfard
- Chair of Thermodynamics, Institute of Power Engineering, Faculty of Mechanical Engineering, Technical University Dresden, 01069 Dresden, Germany
| | - Tommy Lorenz
- Chair of Thermodynamics, Institute of Power Engineering, Faculty of Mechanical Engineering, Technical University Dresden, 01069 Dresden, Germany
| | - Cornelia Breitkopf
- Chair of Thermodynamics, Institute of Power Engineering, Faculty of Mechanical Engineering, Technical University Dresden, 01069 Dresden, Germany
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2
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Shen J, Li X, Li P, Shentu B. Structural and dynamical properties of thermoplastic polyurethane/fullerene nanocomposites: a molecular dynamics simulations study. Phys Chem Chem Phys 2023; 25:27352-27363. [PMID: 37791853 DOI: 10.1039/d3cp03809b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
In this work, the structural and dynamical properties of thermoplastic polyurethane (TPU)/fullerene (C60) nanocomposites are investigated using atomistic molecular dynamics simulations, focusing on the glass transition, thermal expansion, polymer mobility, polymer-C60 interactions, and diffusion behavior of C60. The results show a slight increase in the glass transition temperature (Tg) with increasing C60 weight fraction (wt%), attributed to hindered polymer dynamics, and a remarkable reduction in the coefficient of thermal expansion above Tg. Results of the mean squared displacement and the time decay of bond-reorientation autocorrelation indicate that the mobility of TPU hard segments is more restricted than that of soft segments, owing to the electrostatic attractions and the π-π stacking between isocyanate groups and C60 molecules. Analysis of TPU-C60 interaction energy reveals that the electrostatic interactions are weakened with an increase in the C60 wt%, while the van der Waals contributions become more significant due to the TPU-C60 interfacial characteristics. Further analysis shows that the translational and rotational diffusion of C60 are both increasingly suppressed with the increase of C60 wt%, indicating a violation of Stokes-Einstein (SE) and Stokes-Einstein-Debye (SED) relations, presumably due to the polymer chain-mediated hydrodynamic interactions arising from chain bridges between neighboring C60 particles. This is highlighted by a stronger decoupling of translational-rotational diffusion and a lower ratio of translational-rotational diffusion coefficient (DT/DR) with increasing C60 wt%. This work elucidates an atomistic understanding of the structure and properties of polymer/C60 nanocomposites.
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Affiliation(s)
- Jianxiang Shen
- State Key Lab of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, P. R. China.
- Department of Polymer Science and Technology, Jiaxing University, Jiaxing 314001, China
- Zhejiang Double Arrow Rubber Co., Ltd., Tongxiang 314513, China
| | - Xue Li
- School of Advanced Materials Engineering, Jiaxing Nanhu University, Jiaxing 314001, China.
| | - Ping Li
- Department of Polymer Science and Technology, Jiaxing University, Jiaxing 314001, China
| | - Baoqing Shentu
- State Key Lab of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, P. R. China.
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Ghanta R, Burkhart C, Polińska P, Harmandaris V, Doxastakis M. The effect of chemical constitution on polyisoprene dynamics. J Chem Phys 2023; 159:044902. [PMID: 37486059 DOI: 10.1063/5.0155612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/05/2023] [Indexed: 07/25/2023] Open
Abstract
Polyisoprene (PI) melts have been studied, with most reports focusing on systems with high 1,4-cis content. In contrast, 1,4-trans PI homopolymers or random copolymers have seldom been examined, despite a handful of investigations suggesting a distinct dynamic behavior. Herein, we employ all-atom simulations to investigate the effect of chemical architecture on the dynamics of cis and trans-PI homopolymers, as well as copolymers. We examine the thermodynamic, conformational, and structural properties of the polymers and validate the performance of the models. We probe chain dynamics, revealing that cis-PI presents accelerated translation and reorientation modes relative to trans as recorded by the mean square displacement of the chain center-of-mass as well as by the characteristic times of the lower modes in a Rouse analysis. Interestingly, progressing to higher modes, we observe a reversal with trans units exhibiting faster dynamics. This was further confirmed by calculations of local carbon-hydrogen vector reorientation dynamics, which offer a microscopic view of segmental mobility. To obtain insight into the simulation trajectories, we evaluate the intermediate incoherent scattering function that supports a temperature-dependent crossover in relative mobility that extends over separations beyond the Kuhn-length level. Finally, we analyzed the role of non-Gaussian displacements, which demonstrate that cis-PI exhibits increased heterogeneity in dynamics over short-timescales in contrast to trans-PI, where deviations persist over times extending to terminal dynamics. Our all-atom simulations provide a fundamental understanding of PI dynamics and the impact of microstructure while providing important data for the design and optimization of PI-based materials.
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Affiliation(s)
- Rohit Ghanta
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Tennessee, Knoxville 37996, USA
| | - Craig Burkhart
- The Goodyear Tire & Rubber Company, Akron, Ohio 44305, USA
| | - Patrycja Polińska
- Goodyear Innovation Center Luxembourg, Avenue Gordon Smith, L-7750 Colmar-Berg, Luxembourg
| | - Vagelis Harmandaris
- Department of Applied Mathematics, University of Crete, and IACM FORTH, GR-71110 Heraklion, Greece
- Computation-based Science and Technology Research Center, The Cyprus Institute, Nicosia 2121, Cyprus
| | - Manolis Doxastakis
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Tennessee, Knoxville 37996, USA
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Shamsieva A, Piyanzina I, Minisini B. Amorphous cis-1,4-polybutadiene P-V-T properties from atomistic simulations. J Mol Model 2023; 29:249. [PMID: 37452231 DOI: 10.1007/s00894-023-05658-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 07/08/2023] [Indexed: 07/18/2023]
Abstract
CONTEXT As a result of the diversity of microstructures encountered in cis-1,4-polybutadiene and the variety of measurement methods used, experimental values of variation of glass transition temperature (Tg) with pressure are relatively dispersed. However, atomistic simulations enable access to valuable information for very well-controlled chemistry and structures with a well-defined and systematic acquisition protocol. By varying the temperature and pressure, the specific volume of the melt was computed, yielding results that deviated by only 2% from experimental data. A linear relationship between Tg and pressure was observed, with Tg predicted to be 162 K at zero pressure and a rate of change of Tg with respect to pressure (dTg/dP) of 0.24 K/MPa. METHOD The atomistic dilatometry experiments were conducted on a model of amorphous cis-1,4 polybutadiene with an approximate molecular weight of 5400 g/mol using the LAMMPS code and the all-atom forcefield pcff + . The dilatometry process involved cooling and heating at a rate of 9 × 1012 K/min. The specific volume was calculated by averaging over seven independent configurations for each temperature. The Tait equation was employed to fit the specific volume evolution within the temperature range of 10 to 700 K under different pressures of 0, 60, and 100 MPa.
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Affiliation(s)
- Aigul Shamsieva
- Institute of Physics, Kazan Federal University, Kremlyovskaya St. 18, Kazan, 420008, Republic of Tatarstan, Russia
| | - Irina Piyanzina
- Institute of Physics, Kazan Federal University, Kremlyovskaya St. 18, Kazan, 420008, Republic of Tatarstan, Russia
| | - Benoit Minisini
- Materials Design SARL, 42 Avenue Verdier, 92120, Paris, Montrouge, France.
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Pial TH, Das S. Specific Ion and Electric Field Controlled Diverse Ion Distribution and Electroosmotic Transport in a Polyelectrolyte Brush Grafted Nanochannel. J Phys Chem B 2022; 126:10543-10553. [PMID: 36454705 DOI: 10.1021/acs.jpcb.2c05524] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Controlling ion distribution inside a charged nanochannel is central to using such channels in diverse applications. Here, we show the possibility of using a charged polyelectrolyte (PE) brush-grafted nanochannel for triggering diverse nanoscopic ion distribution and nanofluidic electroosmotic transport by controlling the valence and size of the counterions (that screen the charges of the PE brushes) and the strength of an externally applied axial electric field. We atomistically simulate separate cases of fully charged polyacrylic acid (PAA) brush functionalized nanochannels with Na+, Cs+, Ca2+, Ba2+, and Y3+ counterions screening the PE charges. Four key findings emerge from our simulations. First, we find that the counterions with a greater valence and a smaller size prefer to remain localized inside the brush layer. Second, for the case where there is an added chloride salt with the same cation (as the screening counterions), there are more coions (Cl- ions) in the brush-free bulk than counterions (for counterions Na+, Ca2+, Ba2+, Y3+): this is a manifestation of the overscreening (OS) of the PE brush layer. Contrastingly, the number of Cs+ ions remain higher than the Cl- ions inside the brush-free bulk, ensuring that there is no OS effect for this case. Third, large applied electric field enables a few Na+, Cs+, and Ba2+ counterions to leave the brush layer and to go to the bulk: this makes the OS of the PE brush layer disappear for the cases of PE brushes being screened by the Na+ and Ba2+ ions. On the other hand, no such electric-field-mediated disappearance of OS is observed for the cases of Ca2+ and Y3+ screening counterions; we attribute this to the firm attachment of these counterions to the negatively charged monomers. Free energy associated with a counterion binding to a PE chain corroborates this diversity in the counterion-specific response to the applied electric field. Finally, we demonstrate that such diverse ion distributions, along with specific electric-field-strength-dependent ion properties, lead to (1) electroosmotic (EOS) transport in nanochannels grafted with PAA brushes screened with Cs+ ions to be always counterion dominated, (2) EOS transport in nanochannels grafted with PAA brushes screened with Ca2+ and Y3+ ions to be always coion-dominated, and (3) EOS transport in nanochannels grafted with PAA brushes screened with Na+ and Ba2+ ions to be coion dominated for smaller electric fields and counterion dominated for larger electric fields.
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Affiliation(s)
- Turash Haque Pial
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland20742, United States
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland20742, United States
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Pial TH, Prajapati M, Chava BS, Sachar HS, Das S. Charge-Density-Specific Response of Grafted Polyelectrolytes to Electric Fields: Bending or Tilting? Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Turash Haque Pial
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Mihirkumar Prajapati
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Bhargav Sai Chava
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Harnoor Singh Sachar
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
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In‐noi O, Prasitnok K. A Coarse‐Grained Model for
cis
‐Polyisoprene: Thermal Expansion and Glass Transition Temperature. MACROMOL THEOR SIMUL 2022. [DOI: 10.1002/mats.202100083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Orrasa In‐noi
- Department of Chemistry Faculty of Science Mahasarakham University Mahasarakham 44150 Thailand
| | - Khongvit Prasitnok
- Department of Chemistry Faculty of Science Mahasarakham University Mahasarakham 44150 Thailand
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Sun W, Wu H, Luo Y, Li B, Mao L, Zhao X, Zhang L, Gao Y. Structure and dynamics behavior during the glass transition of the polyisoprene in the presence of pressure: A molecular dynamics simulation. POLYMER 2022. [DOI: 10.1016/j.polymer.2021.124433] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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9
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Nanocomposite of Fullerenes and Natural Rubbers: MARTINI Force Field Molecular Dynamics Simulations. Polymers (Basel) 2021; 13:polym13224044. [PMID: 34833344 PMCID: PMC8626026 DOI: 10.3390/polym13224044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/12/2021] [Accepted: 11/16/2021] [Indexed: 11/16/2022] Open
Abstract
The mechanical properties of natural rubber (NR) composites depend on many factors, including the filler loading, filler size, filler dispersion, and filler-rubber interfacial interactions. Thus, NR composites with nano-sized fillers have attracted a great deal of attention for improving properties such as stiffness, chemical resistance, and high wear resistance. Here, a coarse-grained (CG) model based on the MARTINI force field version 2.1 has been developed and deployed for simulations of cis-1,4-polyisoprene (cis-PI). The model shows qualitative and quantitative agreement with the experiments and atomistic simulations. Interestingly, only a 0.5% difference with respect to the experimental result of the glass transition temperature (Tg) of the cis-PI in the melts was observed. In addition, the mechanical and thermodynamical properties of the cis-PI-fullerene(C60) composites were investigated. Coarse-grained molecular dynamics (MD) simulations of cis-PI-C60 composites with varying fullerene concentrations (0-32 parts per hundred of rubber; phr) were performed over 200 microseconds. The structural, mechanical, and thermal properties of the composites were determined. The density, bulk modulus, thermal expansion, heat capacity, and Tg of the NR composites were found to increase with increasing C60 concentration. The presence of C60 resulted in a slight increasing of the end-to-end distance and radius of the gyration of the cis-PI chains. The contribution of C60 and cis-PI interfacial interactions led to an enhancement of the bulk moduli of the composites. This model should be helpful in the investigations and design of effective fillers of NR-C60 composites for improving their properties.
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Smirnov MA, Tolmachev DA, Glova AD, Sokolova MP, Geydt PV, Lukasheva NV, Lyulin SV. Combined Use of Atomic Force Microscopy and Molecular Dynamics in the Study of Biopolymer Systems. POLYMER SCIENCE SERIES C 2021. [DOI: 10.1134/s1811238221020089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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11
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Assis Silva FC, da Costa Lourenço T, van der Spoel D, Aparicio S, Azevedo Dos Reis R, Costa LT. The structure of CO 2 and CH 4 at the interface of a poly(urethane urea) oligomer model from the microscopic point of view. J Chem Phys 2021; 155:044704. [PMID: 34340392 DOI: 10.1063/5.0049007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The world desperately needs new technologies and solutions for gas capture and separation. To make this possible, molecular modeling is applied here to investigate the structural, thermodynamic, and dynamical properties of a model for the poly(urethane urea) (PUU) oligomer model to selectively capture CO2 in the presence of CH4. In this work, we applied a well-known approach to derive atomic partial charges for atoms in a polymer chain based on self-consistent sampling using quantum chemistry and stochastic dynamics. The interactions of the gases with the PUU model were studied in a pure gas based system as well as in a gas mixture. A detailed structure characterization revealed high interaction of CO2 molecules with the hard segments of the PUU. Therefore, the structural and energy properties explain the reasons for the greater CO2 sorption than CH4. We find that the CO2 sorption is higher than the CH4 with a selectivity of 7.5 at 298 K for the gas mixture. We characterized the Gibbs dividing surface for each system, and the CO2 is confined for a long time at the gas-oligomer model interface. The simulated oligomer model showed performance above the 2008 Robeson's upper bound and may be a potential material for CO2/CH4 separation. Further computational and experimental studies are needed to evaluate the material.
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Affiliation(s)
| | | | - David van der Spoel
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, P.O. Box 596, SE-75124 Uppsala, Sweden
| | | | - Rodrigo Azevedo Dos Reis
- Departamento de Operações e Projetos Industriais, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Luciano T Costa
- MolMod-CS, Departamento de Físico-Química, Universidade Federal Fluminense, Niterói, Brazil
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Zhang Z, Wang Y, Liu P, Chen T, Hou G, Xu L, Wang X, Hu Z, Liu J, Zhang L. Quantitatively predicting the mechanical behavior of elastomers via fully atomistic molecular dynamics simulation. POLYMER 2021. [DOI: 10.1016/j.polymer.2021.123704] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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13
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Li D, Li HT, Wu H, Wang Y. Using the group contribution method and molecular dynamics to predict the glass transition temperatures and mechanical properties of poly-(p-phenylenediamine-alt-2, 6-diformyl multiphenyl). JOURNAL OF CHEMICAL RESEARCH 2021. [DOI: 10.1177/17475198211011696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This article reports the glass transition temperatures of poly-( p-phenylenediamine-alt-2,6-diformyl multiphenyl) predicted by both the group contribution method and the molecular dynamics simulations. The related modeling method and the degree of polymerization, density, specific volume, radius of volume, radius of rotation, and non-bonding energy terms with temperature are analyzed in depth. The bulk modulus, shear modulus, compressibility, Young’s modulus, and Poisson’s ratio of poly-( p-phenylenediamine-alt-2,6-diformyl multiphenyl) at room temperature are simulated by molecular dynamics. The results show that the simulated glass transition temperatures of poly-( p-phenylenediamine-alt-2,6-diformyl multiphenyl) are greater than 480 K, which indicates that poly-( p-phenylenediamine-alt-2,6-diformyl multiphenyl) can be expected to be used as a high-temperature-resistant material. As the number of rigid benzene rings on the molecular side chain increases, the glass transition temperature decreases, with an average decrease of 10 K for each additional benzene ring. The free volume theory can explain the glass transitions of poly-( p-phenylenediamine-alt-2,6-diformyl multiphenyl). The modulus and density of poly-( p-phenylenediamine-alt-2,6-diformyl multiphenyl) change accordingly with an increase of rigid benzene rings on the side chain, probably due to the fact that the flexibility of the polymers changes accordingly as the number of benzene rings on the side chain increases.
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Affiliation(s)
- Duan Li
- College of Chemistry and Chemical Engineering, University of South China, Hengyang, P.R. China
| | - Hui-Ting Li
- College of Chemistry and Chemical Engineering, University of South China, Hengyang, P.R. China
| | - Hongmei Wu
- College of Chemistry and Chemical Engineering, University of South China, Hengyang, P.R. China
- Hunan Key Laboratory for the Design and Application of Actinide Complexes, University of South China, Hengyang, P.R. China
| | - Yuyuan Wang
- College of Chemistry and Chemical Engineering, University of South China, Hengyang, P.R. China
- Hunan Key Laboratory for the Design and Application of Actinide Complexes, University of South China, Hengyang, P.R. China
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Pial TH, Sachar HS, Desai PR, Das S. Overscreening, Co-Ion-Dominated Electroosmosis, and Electric Field Strength Mediated Flow Reversal in Polyelectrolyte Brush Functionalized Nanochannels. ACS NANO 2021; 15:6507-6516. [PMID: 33797221 DOI: 10.1021/acsnano.0c09248] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Controlling the direction and strength of nanofluidic electrohydrodyanmic transport in the presence of an externally applied electric field is extremely important in a number of nanotechnological applications. Here, we employ all-atom molecular dynamics simulations to discover the possibility of changing the direction of electroosmotic (EOS) liquid flows by merely changing the electric field strength in a nanochannel functionalized with polyelectrolyte (PE) brushes. In exploring this, we have uncovered three facets of nanoconfined PE brush behavior and resulting EOS transport. First, we identify the onset of an overscreening effect: such overscreening refers to the presence of more counterions (Na+) within the brush layer than needed to neutralize the negative brush charges. Accordingly, as a consequence of the overscreening, in the bulk liquid outside the brush layer, there is a greater number of co-ions (Cl-) than counterions in the presence of an added salt (NaCl). Second, this specific ion distribution ensures that the overall EOS flow is along the direction of motion of the co-ions. Such co-ion-dictated EOS transport directly contradicts the notion that EOS flow is always dictated by the motion of the counterions. Finally, for large-enough electric fields, the brush height reduces significantly, causing some of the excess overscreening-inducing counterions to squeeze out of the PE brush layer into the brush-free bulk. As a result, the overscreening effect disappears and the number of co-ions and counterions outside the PE brush layer become similar. Despite that there is an EOS transport, this EOS transport, unlike the standard EOS transport that occurs due to the imbalance of the co-ions and counterions, occurs since a larger residence time of the water molecules in the first solvation shell of the counterions (Na+) ensures a water transport in the direction of motion of the counterions. The net effect is the reversal of the direction of the EOS transport by merely changing the strength of the electric field.
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Affiliation(s)
- Turash Haque Pial
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Harnoor Singh Sachar
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Parth Rakesh Desai
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
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15
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Tao L, Chen G, Li Y. Machine learning discovery of high-temperature polymers. PATTERNS (NEW YORK, N.Y.) 2021; 2:100225. [PMID: 33982020 PMCID: PMC8085602 DOI: 10.1016/j.patter.2021.100225] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/21/2021] [Accepted: 03/02/2021] [Indexed: 01/26/2023]
Abstract
To formulate a machine learning (ML) model to establish the polymer's structure-property correlation for glass transition temperatureT g , we collect a diverse set of nearly 13,000 real homopolymers from the largest polymer database, PoLyInfo. We train the deep neural network (DNN) model with 6,923 experimentalT g values using Morgan fingerprint representations of chemical structures for these polymers. Interestingly, the trained DNN model can reasonably predict the unknownT g values of polymers with distinct molecular structures, in comparison with molecular dynamics simulations and experimental results. With the validated transferability and generalization ability, the ML model is utilized for high-throughput screening of nearly one million hypothetical polymers. We identify more than 65,000 promising candidates withT g > 200°C, which is 30 times more than existing known high-temperature polymers (∼2,000 from PoLyInfo). The discovery of this large number of promising candidates will be of significant interest in the development and design of high-temperature polymers.
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Affiliation(s)
- Lei Tao
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - Guang Chen
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - Ying Li
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, USA
- Polymer Program, Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA
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16
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David A, Tartaglino U, Raos G. Towards realistic simulations of polymer networks: tuning vulcanisation and mechanical properties. Phys Chem Chem Phys 2021; 23:3496-3510. [PMID: 33511970 DOI: 10.1039/d0cp05124a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Simulations of coarse-grained network models have long been used to test theoretical predictions about rubber elasticity, while atomistic models are still largely unexplored. Here we devise a novel algorithm for the vulcanisation of united-atom poly(cis-1,4-butadiene), characterize the topology of the resulting networks and test their mechanical properties. We observe clear changes in the network structure when using slower vulcanisation, contrary to the traditional view that cross-linking simply freezes the melt configuration. Non-ideality of our networks reverberates on the distribution of strand length and on the strands deformation, which is highly non-affine, especially for short strands. Nevertheless, we do recover some of the trends observed on ideal bead-and-spring networks and controlled laboratory experiments, such as the linear relationships linking the degree of cross-linking and the density. We also compare different deformation methods and find step-equilibrium protocols to be more reliable. Regardless of the adopted method, it is advisable to precede the deformation by a pre-stretching cycle in order to release internal stresses accumulated during the vulcanisation.
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Affiliation(s)
- Alessio David
- Department of Chemistry, Materials and Chemical Engineering, "G. Natta", Politecnico di Milano, 20131 Milan, Italy
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17
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Lecoutre G, Lemarchand CA, Soulard L, Pineau N. Hugoniostat and Direct Shock Simulations in cis‐1,4‐Polybutadiene Melts. MACROMOL THEOR SIMUL 2020. [DOI: 10.1002/mats.202000068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Claire A. Lemarchand
- CEA, DAM, DIF Arpajon Cedex 91297 France
- Université Paris Saclay, CEA Laboratoire Matière en Conditions Extrêmes Bruyères‐le‐Châtel 91680 France
| | - Laurent Soulard
- CEA, DAM, DIF Arpajon Cedex 91297 France
- Université Paris Saclay, CEA Laboratoire Matière en Conditions Extrêmes Bruyères‐le‐Châtel 91680 France
| | - Nicolas Pineau
- CEA, DAM, DIF Arpajon Cedex 91297 France
- Université Paris Saclay, CEA Laboratoire Matière en Conditions Extrêmes Bruyères‐le‐Châtel 91680 France
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18
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Bregado JL, Tavares FW, Secchi AR, Segtovich ISV. Thermophysical Properties of Amorphous‐Paracrystalline Celluloses by Molecular Dynamics. MACROMOL THEOR SIMUL 2020. [DOI: 10.1002/mats.202000007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jurgen Lange Bregado
- Programa de Engenharia Química/COPPEUniversidade Federal do Rio de JaneiroCidade Universitária Rio de Janeiro CP 21941‐914 Brazil
| | - Frederico Wanderley Tavares
- Programa de Engenharia Química/COPPEUniversidade Federal do Rio de JaneiroCidade Universitária Rio de Janeiro CP 21941‐914 Brazil
- Escola de QuímicaDepartamento de Engenharia QuímicaUniversidade Federal do Rio de JaneiroCidade Universitária Rio de Janeiro CP 21941‐972 Brazil
| | - Argimiro Resende Secchi
- Programa de Engenharia Química/COPPEUniversidade Federal do Rio de JaneiroCidade Universitária Rio de Janeiro CP 21941‐914 Brazil
- Escola de QuímicaDepartamento de Engenharia QuímicaUniversidade Federal do Rio de JaneiroCidade Universitária Rio de Janeiro CP 21941‐972 Brazil
| | - Iuri Soter Viana Segtovich
- Programa de Engenharia Química/COPPEUniversidade Federal do Rio de JaneiroCidade Universitária Rio de Janeiro CP 21941‐914 Brazil
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19
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Molecular dynamics simulations suggest conformational and hydration difference between zwitterionic poly (carboxybetaine methacrylate) and poly (ethylene glycol). Chem Phys 2020. [DOI: 10.1016/j.chemphys.2019.110599] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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20
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Shahidi N, Chazirakis A, Harmandaris V, Doxastakis M. Coarse-graining of polyisoprene melts using inverse Monte Carlo and local density potentials. J Chem Phys 2020; 152:124902. [PMID: 32241142 DOI: 10.1063/1.5143245] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Bottom-up coarse-graining of polymers is commonly performed by matching structural order parameters such as distribution of bond lengths, bending and dihedral angles, and pair distribution functions. In this study, we introduce the distribution of nearest-neighbors as an additional order parameter in the concept of local density potentials. We describe how the inverse-Monte Carlo method provides a framework for forcefield development that is capable of overcoming challenges associated with the parameterization of interaction terms in polymer systems. The technique is applied on polyisoprene melts as a prototype system. We demonstrate that while different forcefields can be developed that perform equally in terms of matching target distributions, the inclusion of nearest-neighbors provides a straightforward route to match both thermodynamic and conformational properties. We find that several temperature state points can also be addressed, provided that the forcefield is refined accordingly. Finally, we examine both the single-particle and the collective dynamics of the coarse-grain models, demonstrating that all forcefields present a similar acceleration relative to the atomistic systems.
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Affiliation(s)
- Nobahar Shahidi
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Antonis Chazirakis
- Department of Mathematics and Applied Mathematics, University of Crete, Heraklion GR-71110, Greece
| | - Vagelis Harmandaris
- Department of Mathematics and Applied Mathematics, University of Crete, Heraklion GR-71110, Greece
| | - Manolis Doxastakis
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA
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21
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Tow GM, Maginn EJ. Fully Atomistic Molecular Dynamics Simulations of Hydroxyl-Terminated Polybutadiene with Insights into Hydroxyl Aggregation. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b02632] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Garrett M. Tow
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Edward J. Maginn
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
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22
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Khuntawee W, Sutthibutpong T, Phongphanphanee S, Karttunen M, Wong-Ekkabut J. Molecular dynamics study of natural rubber-fullerene composites: connecting microscopic properties to macroscopic behavior. Phys Chem Chem Phys 2019; 21:19403-19413. [PMID: 31455965 DOI: 10.1039/c9cp03155c] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Macroscopic and microscopic properties of fullerene (C60)-cis-polyisoprene (cis-PI) composites at varying fullerene concentrations were investigated using atomistic molecular dynamics (MD) simulations over microsecond time scales. Results show that the introduction of fullerenes into a polymer matrix increases density, bulk modulus and heat capacity while thermal expansivity decreases. The presence of fullerenes slowed the diffusion of both C60 and cis-PI. Moreover, increasing fullerene concentration results in ordering of the cis-PI chains at the cis-PI-fullerene interfaces and shrinking of bulk PI regions. Free energy calculations of fullerene dimerization suggest that fullerenes disperse at low and aggregate at high fullerene concentrations. Our multi-scaled analysis approach demonstrates the role of 'ordered' regions adjacent to the interface between cis-PI and fullerene in controlling the level of order and mobility of the cis-PI chains. The relationship between the microscopic behavior and the changes in mechanical and thermal properties are discussed. Our study is beneficial for further studies and development of advanced rubber technology for novel, cost-effective, material with very high stiffness and thermal endurance with optimizing conditions of filler contents.
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Affiliation(s)
- Wasinee Khuntawee
- Computational Biomodelling Laboratory for Agricultural Science and Technology (CBLAST), Faculty of Science, Kasetsart University, Bangkok 10900, Thailand. and Department of Physics, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand and Thailand Center of Excellence in Physics (ThEP Center), Commission on Higher Education, Bangkok 10400, Thailand
| | - Thana Sutthibutpong
- Computational Biomodelling Laboratory for Agricultural Science and Technology (CBLAST), Faculty of Science, Kasetsart University, Bangkok 10900, Thailand. and Thailand Center of Excellence in Physics (ThEP Center), Commission on Higher Education, Bangkok 10400, Thailand and Theoretical and Computational Science Center (TaCS), Science Laboratory Building, Faculty of Science, King Mongkut's University of Technology Thonburi (KMUTT), 126 Pracha-Uthit Road, Bang Mod, Thrung Khru, Bangkok 10140, Thailand
| | - Saree Phongphanphanee
- Computational Biomodelling Laboratory for Agricultural Science and Technology (CBLAST), Faculty of Science, Kasetsart University, Bangkok 10900, Thailand. and Thailand Center of Excellence in Physics (ThEP Center), Commission on Higher Education, Bangkok 10400, Thailand and Department of Material Science, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand and Specialized Center of Rubber and Polymer Materials for Agriculture and Industry (RPM), Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Mikko Karttunen
- Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada and Department of Applied Mathematics, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada and The Centre of Advanced Materials and Biomaterials Research, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada
| | - Jirasak Wong-Ekkabut
- Computational Biomodelling Laboratory for Agricultural Science and Technology (CBLAST), Faculty of Science, Kasetsart University, Bangkok 10900, Thailand. and Department of Physics, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand and Thailand Center of Excellence in Physics (ThEP Center), Commission on Higher Education, Bangkok 10400, Thailand and Specialized Center of Rubber and Polymer Materials for Agriculture and Industry (RPM), Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
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23
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Dahal UR, Prhashanna A, Dormidontova EE. Hydration of diblock copolymer micelles: Effects of hydrophobicity and co-solvent. J Chem Phys 2019; 150:184908. [PMID: 31091932 DOI: 10.1063/1.5089251] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Diblock polymer micelles dispersed in an aqueous environment are being actively investigated for various applications, but there is only a qualitative understanding of the effect of the chemical structure on the micelle hydration and water dynamics as these properties are difficult to assess experimentally. Using all-atom molecular dynamics simulations, we investigate aqueous solutions of three comparable in size diblock copolymer micelles with core-forming blocks of different hydrophobicity: polybutadiene (PB), polycaprolactone (PCL), and polytetrahydrofuran (pTHF) with the same hydrophilic block, polyethylene oxide (PEO). We found that core-block hydrophobicity and ability to form hydrogen bonds with water strongly affect the water dynamics near the core: water molecules spend considerably less time in contact with the PB block than with PCL and pTHF blocks. We obtained polymer and solvent volume fraction profiles and determined that the interfacial width systematically increases with a decrease of core block hydrophobicity with water penetration into the core being negligible for PB-PEO and PCL-PEO micelles, while for pTHF-PEO micelles the interface is more diffuse and there is a noticeable penetration of water (17% by volume). For PCL-PEO micelles, which are commonly used in biomedical applications, we also investigated tetrahydrofuran (THF) penetration into the micelles from mixed THF:water solution at early stages of micelle dissolution. We found an inhomogeneous solvent distribution with a maximum of THF volume fraction in the interfacial core-corona region and partial exclusion from the PEO corona, which slows down micelle dissolution. These results can have important implications for micelle stability and use in biomedical applications.
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Affiliation(s)
- Udaya R Dahal
- Polymer Program, Institute of Materials Science and Physics Department, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Ammu Prhashanna
- Polymer Program, Institute of Materials Science and Physics Department, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Elena E Dormidontova
- Polymer Program, Institute of Materials Science and Physics Department, University of Connecticut, Storrs, Connecticut 06269, USA
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24
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Sharma P, Roy S, Karimi‐Varzaneh HA. Impact of Plasticizer Addition on Molecular Properties of Polybutadiene Rubber and its Manifestations to Glass Transition Temperature. MACROMOL THEOR SIMUL 2019. [DOI: 10.1002/mats.201900003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Pragati Sharma
- Physical and Material Chemistry DivisionCSIR‐National Chemical Laboratory Dr. Homi Bhabha Road Pune 411008 India
- Academy of Scientific and Innovative Research Delhi—Mathura Road New Delhi 110025 India
| | - Sudip Roy
- Physical and Material Chemistry DivisionCSIR‐National Chemical Laboratory Dr. Homi Bhabha Road Pune 411008 India
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25
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Hu C, Lu T, Guo H. Developing a Transferable Coarse-Grained Model for the Prediction of Thermodynamic, Structural, and Mechanical Properties of Polyimides at Different Thermodynamic State Points. J Chem Inf Model 2019; 59:2009-2025. [DOI: 10.1021/acs.jcim.8b00887] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Chenchen Hu
- Beijing National Laboratory for Molecular Sciences, Joint Laboratory of Polymer Sciences and Materials, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Teng Lu
- Beijing National Laboratory for Molecular Sciences, Joint Laboratory of Polymer Sciences and Materials, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Hongxia Guo
- Beijing National Laboratory for Molecular Sciences, Joint Laboratory of Polymer Sciences and Materials, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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26
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Kempfer K, Devémy J, Dequidt A, Couty M, Malfreyt P. Realistic Coarse-Grain Model of cis-1,4-Polybutadiene: From Chemistry to Rheology. Macromolecules 2019. [DOI: 10.1021/acs.macromol.8b02750] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- K. Kempfer
- CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, Université Clermont Auvergne, F-63000 Clermont-Ferrand, France
- Manufacture Française des Pneumatiques Michelin, 23, Place des Carmes, 63040 Clermont-Ferrand, France
| | - J. Devémy
- CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, Université Clermont Auvergne, F-63000 Clermont-Ferrand, France
| | - A. Dequidt
- CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, Université Clermont Auvergne, F-63000 Clermont-Ferrand, France
| | - M. Couty
- Manufacture Française des Pneumatiques Michelin, 23, Place des Carmes, 63040 Clermont-Ferrand, France
| | - P. Malfreyt
- CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, Université Clermont Auvergne, F-63000 Clermont-Ferrand, France
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27
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Saha S, Bhowmick AK. An Insight into molecular structure and properties of flexible amorphous polymers: A molecular dynamics simulation approach. J Appl Polym Sci 2019. [DOI: 10.1002/app.47457] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Subhabrata Saha
- Rubber Technology Centre; Indian Institute of Technology; Kharagpur 721 302 India
| | - Anil K. Bhowmick
- Rubber Technology Centre; Indian Institute of Technology; Kharagpur 721 302 India
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28
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Martinez-Pardo I, Shanks RA, Adhikari R, Adhikari B. Natural Rubber with Polyhedral Oligomeric Silsesquioxane, Nanocomposites, and Hybrids Compared by Molecular Modeling. MACROMOL THEOR SIMUL 2018. [DOI: 10.1002/mats.201800026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Isaac Martinez-Pardo
- School of Science; RMIT University; 124 La Trobe St Melbourne VIC 3000 Australia
| | - Robert A. Shanks
- School of Science; RMIT University; 124 La Trobe St Melbourne VIC 3000 Australia
| | - Raju Adhikari
- CSIRO Manufacturing; Clayton South VIC 3169 Australia
| | - Benu Adhikari
- School of Science; RMIT University; 124 La Trobe St Melbourne VIC 3000 Australia
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29
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30
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Volgin I, Larin S, Lyulin A, Lyulin S. Coarse-grained molecular-dynamics simulations of nanoparticle diffusion in polymer nanocomposites. POLYMER 2018. [DOI: 10.1016/j.polymer.2018.04.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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31
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Sharma P, Chakrabarty S, Roy S, Kumar R. Molecular View of CO 2 Capture by Polyethylenimine: Role of Structural and Dynamical Heterogeneity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:5138-5148. [PMID: 29641903 DOI: 10.1021/acs.langmuir.8b00204] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The molecular thermodynamics and kinetics of CO2 sorption in Polyethylenimine (PEI) melt have been investigated systematically using GCMC and MD simulations. We elucidate presence of significant structural and dynamic heterogeneity associated with the overall absorption process. CO2 adsorption in a PEI membrane shows a distinct two-stage process of a rapid CO2 adsorption at the interfaces (hundreds of picoseconds) followed by a significantly slower diffusion limited release toward the interior bulk regions of PEI melt (hundreds of nanoseconds to microseconds). The spatial heterogeneity of local structural features of the PEI chains lead to significantly heterogeneous absorption characterized by clustering and trapping of CO2 molecules that then lead to subdiffusive motion of CO2. In the complex interplay of interaction and entropy, the latter emerges out to be the major determining factor with significantly higher solubility of CO2 near the interfaces despite having lower density of binding amine groups. Regions having higher free-volume (entropically favorable) viz. interfaces, pores and loops demonstrate higher CO2 capture ability. Various local structural features of PEI conformations, for example, inter- and intrachain loops, pores of different radii, and di- or tricoordinated pores are explored for their effects on the varying CO2 adsorption abilities.
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Affiliation(s)
- Pragati Sharma
- Physical and Materials Chemistry Division , CSIR-National Chemical Laboratory , Dr. Homi Bhabha Road , Pune - 411 008 , India
- Academy of Scientific and Innovative Research , Delhi - Mathura Road , New Delhi 110025 , India
| | - Suman Chakrabarty
- School of Chemical Sciences , National Institute of Science Education and Research , P.O. Bhimpur-Padanpur , Via Jatni, Khurda Odisha 752050 , India
| | - Sudip Roy
- Physical and Materials Chemistry Division , CSIR-National Chemical Laboratory , Dr. Homi Bhabha Road , Pune - 411 008 , India
| | - Rajnish Kumar
- Department of Chemical Engineering , Indian Institute of Technology Madras , Chennai 600 036 , Tamil Nadu India
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32
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Glova AD, Larin SV, Falkovich SG, Nazarychev VM, Tolmachev DA, Lukasheva NV, Lyulin SV. Molecular dynamics simulations of oligoester brushes: the origin of unusual conformations. SOFT MATTER 2017; 13:6627-6638. [PMID: 28926071 DOI: 10.1039/c7sm01419h] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present results from all-atom molecular dynamics simulations for the structural properties of oligomeric lactic acid chains (OLA) grafted to the surface of cellulose nanocrystals (CNCs) and immersed in the melt of polylactic acid (PLA). Earlier, we have found that the distribution of free ends of OLA molecules is bimodal [Glova et al., Polym. Int., 2016, 65(8), 892]. The results cannot be explained within the standard picture of uncharged polymer brushes exposed to the melt of a chemically identical polymer. Although the oligomeric brushes of the OLA chains are uncharged, they have partial polarization charges producing a non-zero dipole moment of the monomeric chain unit. We study the influence of partial charges on the structure of the layer of OLA chains grafted to the CNC surface. A detailed analysis of the conformations of the grafted chains shows that interaction of partial charges in the models causes bending of the OLA molecules toward the cellulose surface, forming a hairpin structure. The observed separation of the grafted chains into two populations increases with grafting density. We demonstrate that hydrogen bonds can be formed between the free ends of the grafted chains and the CNC surface, but they do not affect the brush structure significantly. Thus, dipole-dipole interactions turn out to be the key factor governing the unusual conformations of grafts.
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Affiliation(s)
- A D Glova
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoj pr. V.O., 31, 199004 Saint Petersburg, Russia.
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33
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Meyer J, Hentschke R, Hager J, Hojdis NW, Karimi-Varzaneh HA. Molecular Simulation of Viscous Dissipation due to Cyclic Deformation of a Silica–Silica Contact in Filled Rubber. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00947] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Jan Meyer
- School
of Mathematics and Natural Sciences Bergische Universität D-42097 Wuppertal, Germany
| | - Reinhard Hentschke
- School
of Mathematics and Natural Sciences Bergische Universität D-42097 Wuppertal, Germany
| | - Jonathan Hager
- School
of Mathematics and Natural Sciences Bergische Universität D-42097 Wuppertal, Germany
| | - Nils W. Hojdis
- Continental Reifen Deutschland GmbH D-30419 Hannover, Germany
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34
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Pavlov AS, Khalatur PG. Filler reinforcement in cross-linked elastomer nanocomposites: insights from fully atomistic molecular dynamics simulation. SOFT MATTER 2016; 12:5402-5419. [PMID: 27225453 DOI: 10.1039/c6sm00543h] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using a fully atomistic model, we perform large-scale molecular dynamics simulations of sulfur-cured polybutadiene (PB) and nanosilica-filled PB composites. A well-integrated network without sol fraction is built dynamically by cross-linking the coarse-grained precursor chains in the presence of embedded silica nanoparticles. Initial configurations for subsequent atomistic simulations are obtained by reverse mapping of the well-equilibrated coarse-grained systems. Based on the concept of "maximally inflated knot" introduced by Grosberg et al., we show that the networks simulated in this study behave as mechanically isotropic systems. Analysis of the network topology in terms of graph theory reveals that mechanically inactive tree-like structures are the dominant structural components of the weakly cross-linked elastomer, while cycles are mainly responsible for the transmission of mechanical forces through the network. We demonstrate that quantities such as the system density, thermal expansion coefficient, glass transition temperature and initial Young's modulus can be predicted in qualitative and sometimes even in quantitative agreement with experiments. The nano-filled system demonstrates a notable increase in the glass transition temperature and an approximately two-fold increase in the nearly equilibrium value of elastic modulus relative to the unfilled elastomer even at relatively small amounts of filler particles. We also examine the structural rearrangement of the nanocomposite subjected to tensile deformation. Under high strain-rate loading, the formation of structural defects (microcavities) within the polymer bulk is observed. The nucleation and growth of cavities in the post-yielding strain hardening regime mainly take place at the elastomer/nanoparticle interfaces. As a result, the cavities are concentrated just near the embedded nanoparticles. Therefore, while the silica nanofiller increases the elastic modulus of the elastomer, it also creates a more defective structure of higher energy in comparison with the unfilled network.
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Affiliation(s)
- Alexander S Pavlov
- Department of Physical Chemistry, Tver State University, Tver, 170100, Russia.
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35
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Fully atomistic molecular dynamics simulation of nanosilica-filled crosslinked polybutadiene. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.04.061] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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