1
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Zhang F, Wang W, Zhao Y, He X. Dynamics and Internal Structure Evolution during the Glass Transition of the Ethylene-Cyclic Olefin Copolymers: A Molecular Dynamics Simulation. J Phys Chem B 2024; 128:5135-5146. [PMID: 38728026 DOI: 10.1021/acs.jpcb.4c01286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2024]
Abstract
Amorphous ethylene-cyclic olefin copolymers (COCs) which can be used in cell phone lenses and prefilled syringes have attracted increasing attention due to their excellent and tunable thermal properties. In order to better explain the influence of COC microstructure (cyclic olefin types and content) on the glass transition mechanism, we used molecular dynamics (MD) simulations to track the evolution of free volume, diffusion coefficients, atomic mobility, trans conformation probabilities, and characteristic parameters of α-relaxation kinetics during the quenching process. MD results show that for the classic COC E-co-NB (ethylene-norbornene copolymer), an increase in cyclic olefin content from 25 to 50 mol % reduces atomic mobility, limiting the molecular chain movement at higher temperatures and improving Tg. Compared to NB, the more rigid rings in tricyclopentadiene (TCPD) and exo-1,4,4a,9,9a,10-hexahydro-9,10(1',2')-bridged phenylidene-1,4-bridged methylideneanthracene (HBM) have the following effects: (1) reducing the thermal expansion coefficient and overall chain mobility; (2) enhancing the diffusion energy barrier; (3) promoting the formation of local ordered structures; (4) accelerating α-relaxation dynamics at high temperatures and improving the dynamic fragility m. These lead to an upward shift in the temperature region where chain movement is limited and thus improve Tg and high-temperature dimensional stability. In this simulation, the correlation equation between Tg, m, and the microstructural parameters of COCs is established, which is of great significance for the development of COCs with high performance.
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Affiliation(s)
- Fan Zhang
- Shanghai Key Laboratory of Multiphase Material Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Wenhui Wang
- Shanghai Key Laboratory of Multiphase Material Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Yangyang Zhao
- Shanghai Key Laboratory of Multiphase Material Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Xuelian He
- Shanghai Key Laboratory of Multiphase Material Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China
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2
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Gao H, Shi R, Zhu Y, Qian H, Lu Z. Coarse-grained Dynamics Simulation in Polymer Systems: from Structures to Material Properties. Chem Res Chin Univ 2022. [DOI: 10.1007/s40242-022-2080-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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3
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Relaxation behavior of polymer thin films: Effects of free surface, buried interface, and geometrical confinement. Prog Polym Sci 2021. [DOI: 10.1016/j.progpolymsci.2021.101431] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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4
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Xu WS, Douglas JF, Xu X. Role of Cohesive Energy in Glass Formation of Polymers with and without Bending Constraints. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01876] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Wen-Sheng Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Xiaolei Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
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5
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Storey AN, Zhang W, Douglas JF, Starr FW. How Does Monomer Structure Affect the Interfacial Dynamics of Supported Ultrathin Polymer Films? Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01413] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Amber N. Storey
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459-0155, United States
| | - Wengang Zhang
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459-0155, United States
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jack F. Douglas
- Materials Science and Engineering Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Francis W. Starr
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459-0155, United States
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6
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Xu WS, Douglas JF, Xu X. Molecular Dynamics Study of Glass Formation in Polymer Melts with Varying Chain Stiffness. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c00731] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Wen-Sheng Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Xiaolei Xu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China
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7
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Alesadi A, Xia W. Understanding the Role of Cohesive Interaction in Mechanical Behavior of a Glassy Polymer. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c00067] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Amirhadi Alesadi
- Department of Civil & Environmental Engineering, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Wenjie Xia
- Department of Civil & Environmental Engineering, North Dakota State University, Fargo, North Dakota 58108, United States
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8
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Li SJ, Qian HJ, Lu ZY. A simulation study on the glass transition behavior and relevant segmental dynamics in free-standing polymer nanocomposite films. SOFT MATTER 2019; 15:4476-4485. [PMID: 31111851 DOI: 10.1039/c9sm00267g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In polymer/nanoparticle composite (PNC) thin films, polymer chains experience strong confinement effects not only at the free surface area but also from nanoparticles (NPs). In this work, the influence of NP-polymer interaction and NP distribution on the polymer segmental dynamics and the glass transition behavior of PNC free-standing films are investigated through molecular dynamics simulations. We demonstrate that NPs will migrate to the film surface area and form an NP-concentrated layer when NP-polymer interactions are weak, while NPs are well dispersed in the bulk region when NP-polymer interactions are strong. In both cases, we find increases in the glass transition temperature Tg compared with the pure film without NPs, although with a different degree. The weakly interacting system has the same Tg as the pure bulk system without NPs. The NP layer formed at the surface area reduces both the mobility of the surface polymer beads and the mobility gradient in the film normal direction (MGFND), therefore resulting in an increase in the Tg which highlights the vital role of the mobile surface layer. In contrast, the NPs in the bulk region enlarge the MGFND. NPs have opposite influences on the polymer bead dynamic anisotropy when they interact weakly or strongly with polymers, weakened for the former and enhanced for the latter. These findings offer a clear picture of the segmental dynamics and glass transition behavior in free-standing PNC films with different NP-polymer interaction strengths. We hope these results will be helpful for the property design of related materials.
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Affiliation(s)
- Shu-Jia Li
- State Key Laboratory of Supramolecular Structure and Materials, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130021, China.
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9
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Jain T, Clay W, Tseng YM, Vishwakarma A, Narayanan A, Ortiz D, Liu Q, Joy A. Role of pendant side-chain length in determining polymer 3D printability. Polym Chem 2019. [DOI: 10.1039/c9py00879a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The effect of polymer side chain on extrusion-based direct-write 3D printing and rheology is examined. Longer side chain length improves printability at ambient temperatures.
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Affiliation(s)
- Tanmay Jain
- Department of Polymer Science
- The University of Akron
- Akron
- USA
| | - William Clay
- Department of Polymer Science
- The University of Akron
- Akron
- USA
- Department of Chemistry & Biochemistry
| | - Yen-Ming Tseng
- Department of Polymer Science
- The University of Akron
- Akron
- USA
| | | | - Amal Narayanan
- Department of Polymer Science
- The University of Akron
- Akron
- USA
| | - Deliris Ortiz
- Department of Polymer Science
- The University of Akron
- Akron
- USA
| | - Qianhui Liu
- Department of Polymer Science
- The University of Akron
- Akron
- USA
| | - Abraham Joy
- Department of Polymer Science
- The University of Akron
- Akron
- USA
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10
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Olaya-Muñoz DA, Nealey PF, Hernández-Ortiz JP. Leveling of Polymer Grating Structures upon Heating: Dimension Dependence on the Nanoscale and the Effect of Antiplasticizers. ACS APPLIED MATERIALS & INTERFACES 2018; 10:27432-27443. [PMID: 30033719 DOI: 10.1021/acsami.8b06611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The transition temperatures of nanoscale polymeric films are measured from a leveling experiment where a designed nanostructure is heated from below. Surface tension forces drive the relaxation of the polymeric features, allowing direct measurement of the critical temperature of collapse, Tflow, and indirect measurement of the glass transition temperature, TG. Small-angle X-ray scattering and atomic force microscopy are used to follow the leveling dynamics, whereas a mathematical model for the momentum balance is implemented to extract the viscosity of the polymer film as a function of temperature. Our methodology is illustrated in the context of films of poly(methyl methacrylate) that are patterned via nanoimprint lithography into dense gratings. We study how the glass transition temperature and the critical temperature of collapse vary as a function of the film size and the inclusion of the antiplasticizer, tris(2-chloropropyl) phosphate. The grating periods are varied consistently between 80 and 240 nm, whereas the antiplasticizer concentrations are 1, 3, 5, and 10 wt %. The solution of the momentum balance allows the detailed correlation between stresses, curvature, heating, and shear rates during leveling. We found that both temperatures, TG and Tflow, decrease as the film size decreases or as the concentration of the antiplasticizer increases. In addition, antiplasticizer concentrations between 3 and 5 wt % stabilize the size dependence of Tflow. We show that the nature of the antiplasticizer is effectively to increase the low-temperature viscosity of the film. However, during leveling, the antiplasticized film sustains its curvature, thereby driving a sudden relaxation, once TG is reached, and increasing the possibilities of defects.
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Affiliation(s)
- Daniel A Olaya-Muñoz
- Departamento de Materiales y Nanotecnología , Universidad Nacional de Colombia-Medellín , Medellín , 050034 , Colombia
| | - Paul F Nealey
- Institute for Molecular Engineering , University of Chicago , Chicago , Illinois 60637 , United States
- Materials Science Division , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Juan P Hernández-Ortiz
- Departamento de Materiales y Nanotecnología , Universidad Nacional de Colombia-Medellín , Medellín , 050034 , Colombia
- The Biotechnology Center , University of Wisconsin-Madison , Madison , Wisconsin 53706 , United States
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11
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Xia W, Song J, Hsu DD, Keten S. Side-group size effects on interfaces and glass formation in supported polymer thin films. J Chem Phys 2018; 146:203311. [PMID: 28571359 DOI: 10.1063/1.4976702] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Recent studies on glass-forming polymers near interfaces have emphasized the importance of molecular features such as chain stiffness, side-groups, molecular packing, and associated changes in fragility as key factors that govern the magnitude of Tg changes with respect to the bulk in polymer thin films. However, how such molecular features are coupled with substrate and free surface effects on Tg in thin films remains to be fully understood. Here, we employ a chemically specific coarse-grained polymer model for methacrylates to investigate the role of side-group volume on glass formation in bulk polymers and supported thin films. Our results show that bulkier side-groups lead to higher bulk Tg and fragility and are associated with a pronounced free surface effect on overall Tg depression. By probing local Tg within the films, however, we find that the polymers with bulkier side-groups experience a reduced confinement-induced increase in local Tg near a strongly interacting substrate. Further analyses indicate that this is due to the packing frustration of chains near the substrate interface, which lowers the attractive interactions with the substrate and thus lessens the surface-induced reduction in segmental mobility. Our results reveal that the size of the polymer side-group may be a design element that controls the confinement effects induced by the free surface and substrates in supported polymer thin films. Our analyses provide new insights into the factors governing polymer dynamics in bulk and confined environments.
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Affiliation(s)
- Wenjie Xia
- Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, USA
| | - Jake Song
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, USA
| | - David D Hsu
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, USA
| | - Sinan Keten
- Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, USA
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12
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Qiu X, Zhang Y, Wu H, Yang R, Yang J, Liu R, Liu Y, Zhou Z, Hao T, Nie Y. Blocked crystallization in capped ultrathin polymer films studied by molecular simulations. POLYM INT 2018. [DOI: 10.1002/pi.5549] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Xiaoyan Qiu
- Institute of Polymer Materials, School of Materials Science and Engineering; Jiangsu University; Zhenjiang China
| | - Yongqiang Zhang
- Institute of Polymer Materials, School of Materials Science and Engineering; Jiangsu University; Zhenjiang China
| | - Haitao Wu
- Institute of Polymer Materials, School of Materials Science and Engineering; Jiangsu University; Zhenjiang China
| | - Rui Yang
- Institute of Polymer Materials, School of Materials Science and Engineering; Jiangsu University; Zhenjiang China
| | - Jun Yang
- Institute of Polymer Materials, School of Materials Science and Engineering; Jiangsu University; Zhenjiang China
| | - Rongjuan Liu
- Institute of Polymer Materials, School of Materials Science and Engineering; Jiangsu University; Zhenjiang China
| | - Yong Liu
- Institute of Polymer Materials, School of Materials Science and Engineering; Jiangsu University; Zhenjiang China
| | - Zhiping Zhou
- Institute of Polymer Materials, School of Materials Science and Engineering; Jiangsu University; Zhenjiang China
| | - Tongfan Hao
- Institute of Green Chemistry and Chemical Technology; Jiangsu University; Zhenjiang China
| | - Yijing Nie
- Institute of Polymer Materials, School of Materials Science and Engineering; Jiangsu University; Zhenjiang China
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13
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Zhu YL, Pan D, Li ZW, Liu H, Qian HJ, Zhao Y, Lu ZY, Sun ZY. Employing multi-GPU power for molecular dynamics simulation: an extension of GALAMOST. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1434904] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- You-Liang Zhu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin Province, China
| | - Deng Pan
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin Province, China
| | - Zhan-Wei Li
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin Province, China
| | - Hong Liu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, Jilin Province, China
| | - Hu-Jun Qian
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, Jilin Province, China
| | - Yang Zhao
- National Supercomputer Center in Tianjin, Tianjin, China
| | - Zhong-Yuan Lu
- State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, Jilin Province, China
| | - Zhao-Yan Sun
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin Province, China
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14
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Jin K, Torkelson JM. T g -confinement effects in strongly miscible blends of poly(2,6-dimethyl-1,4-phenylene oxide) and polystyrene: Roles of bulk fragility and chain segregation. POLYMER 2017. [DOI: 10.1016/j.polymer.2017.04.069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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15
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Lyulin AV, Balabaev NK, Baljon ARC, Mendoza G, Frank CW, Yoon DY. Interfacial and topological effects on the glass transition in free-standing polystyrene films. J Chem Phys 2017; 146:203314. [DOI: 10.1063/1.4977042] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Mangalara JH, Marvin MD, Wiener NR, Mackura ME, Simmons DS. Does fragility of glass formation determine the strength ofTg-nanoconfinement effects? J Chem Phys 2017; 146:104902. [DOI: 10.1063/1.4976521] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Jayachandra Hari Mangalara
- Department of Polymer Engineering, The University of Akron, 250 South Forge Street, Akron, Ohio 44325-0301, USA
| | - Michael D. Marvin
- Department of Polymer Engineering, The University of Akron, 250 South Forge Street, Akron, Ohio 44325-0301, USA
| | - Nicholas R. Wiener
- Department of Polymer Engineering, The University of Akron, 250 South Forge Street, Akron, Ohio 44325-0301, USA
| | - Mark E. Mackura
- Department of Polymer Engineering, The University of Akron, 250 South Forge Street, Akron, Ohio 44325-0301, USA
| | - David S. Simmons
- Department of Polymer Engineering, The University of Akron, 250 South Forge Street, Akron, Ohio 44325-0301, USA
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17
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Cho HW, Sung BJ. The glass transition and interfacial dynamics of single strand fibers of polymers. SOFT MATTER 2017; 13:1190-1199. [PMID: 28098313 DOI: 10.1039/c6sm02468h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We investigate the glass transition and interfacial dynamics of single strand fibers of flexible polymers by employing molecular dynamics (MD) simulations along with a coarse grained model. While the polymer fiber has drawn significant attention due to its applicability in tissue engineering and stretchable electronics, its dynamic properties, especially the glass transition temperature (Tg), are yet to be understood at the molecular level. For example, there has been a controversy on the effect of the polymer fiber radius (R) on Tg: Tg decreased with a decrease in R for some polymer fibers, whereas Tg of other polymer fibers was not sensitive to R. In this article, we estimate the bond relaxation time of polymers and evaluate both Tg and fragility (m) as a function of R. We illustrate that Tg of the polymer fiber decreased with a decrease in R monotonically and also that the values of Tg follow faithfully the empirical equation proposed by Keddie et al. as a function of R, which was successfully employed to fit the values of Tg of both polyvinyl alcohol (PVA) fibers and polyethylene (PE) fibers. We also find that the dynamics of polymers at the interface between a polymer fiber and air is faster than that of polymers at the center. By employing Adam-Gibbs theory, we show that the fast interface dynamics of polymer fibers should influence the cooperative motion of monomers, which should be responsible for the decrease in Tg for smaller values of R. Near the interface there are more mobile monomers that participate in the cooperative motions of polymers. Interesting is that due to the curved surface (unlike flat polymer films) the cooperative motion of monomers is anisotropic in polymer fibers.
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Affiliation(s)
- Hyun Woo Cho
- Department of Chemistry and Research Institute for Basic Science, Sogang University, Seoul 121-742, Republic of Korea.
| | - Bong June Sung
- Department of Chemistry and Research Institute for Basic Science, Sogang University, Seoul 121-742, Republic of Korea.
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18
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Xu WS, Douglas JF, Freed KF. Influence of Cohesive Energy on the Thermodynamic Properties of a Model Glass-Forming Polymer Melt. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b01503] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Jack F. Douglas
- Materials
Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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19
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Jin K, Torkelson JM. Enhanced Tg-Confinement Effect in Cross-Linked Polystyrene Compared to Its Linear Precursor: Roles of Fragility and Chain Architecture. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b01042] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Kailong Jin
- Department of Chemical and Biological
Engineering and ‡Department of Materials Science
and Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - John M. Torkelson
- Department of Chemical and Biological
Engineering and ‡Department of Materials Science
and Engineering, Northwestern University, Evanston, Illinois 60208, United States
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20
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Hsu DD, Xia W, Song J, Keten S. Glass-Transition and Side-Chain Dynamics in Thin Films: Explaining Dissimilar Free Surface Effects for Polystyrene vs Poly(methyl methacrylate). ACS Macro Lett 2016; 5:481-486. [PMID: 35607230 DOI: 10.1021/acsmacrolett.6b00037] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Despite having very similar bulk properties such as glass-transition temperature (Tg), density, and fragility, polystyrene (PS) and poly(methyl methacrylate) (PMMA) exhibit characteristically different Tg depression in free-standing ultrathin films due to free surface effects. Here we explain this difference using our recently established chemistry-specific coarse-grained (CG) models for these two polymers. Models capture the dissimilar scaling of Tg with free-standing film thickness as seen in experiments and enable us to quantify the size of the regions near free surfaces over which chain relaxation exhibits differences from bulk. Most interestingly, vibrational density of states (VDOS) analysis uncovers a relationship between the amplitude of side-chain fluctuations, associated with side-chain flexibility and Tg-nanoconfinement. We discover that increasing backbone to side-chain mass ratio in CG models increases the amplitude of side-chain fluctuations and suppresses the free-surface effect on Tg. We show that mass distribution and side-chain flexibility are central to explain dissimilar free surface effects on PS and PMMA. Our model predictions are further corroborated by experimental evidence showing the role of mass distribution in styrene thin films. Our study ascertains the significance of molecular characteristics on nanoconfinement and highlights the ability for chemistry-specific CG models to explore the thermomechanical properties of polymer thin films.
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Affiliation(s)
- David D. Hsu
- Department of Mechanical Engineering, ‡Department of Civil & Environmental Engineering, and §Department of Materials Science & Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - Wenjie Xia
- Department of Mechanical Engineering, ‡Department of Civil & Environmental Engineering, and §Department of Materials Science & Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - Jake Song
- Department of Mechanical Engineering, ‡Department of Civil & Environmental Engineering, and §Department of Materials Science & Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - Sinan Keten
- Department of Mechanical Engineering, ‡Department of Civil & Environmental Engineering, and §Department of Materials Science & Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
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21
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Lan T, Torkelson JM. Fragility-Confinement Effects: Apparent Universality as a Function of Scaled Thickness in Films of Freely Deposited, Linear Polymer and Its Absence in Densely Grafted Brushes. Macromolecules 2016. [DOI: 10.1021/acs.macromol.5b02489] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tian Lan
- Department of Materials Science
and Engineering and ‡Department of Chemical and Biological
Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - John M. Torkelson
- Department of Materials Science
and Engineering and ‡Department of Chemical and Biological
Engineering, Northwestern University, Evanston, Illinois 60208, United States
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22
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Nie Y, Zhou Z, Hao T, Ye X, Yang W. The Distribution of Glass Transition Temperatures in Ultrathin Polymer Films Controlled by Segment Density or Interfacial Interaction. MACROMOL THEOR SIMUL 2016. [DOI: 10.1002/mats.201500062] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yijing Nie
- Institute of Polymer Materials; School of Materials Science and Engineering; Jiangsu University; 301 Xuefu Road Zhenjiang 212013 China
| | - Zhiping Zhou
- Institute of Polymer Materials; School of Materials Science and Engineering; Jiangsu University; 301 Xuefu Road Zhenjiang 212013 China
| | - Tongfan Hao
- Institute of Polymer Materials; School of Materials Science and Engineering; Jiangsu University; 301 Xuefu Road Zhenjiang 212013 China
| | - Xubo Ye
- Institute of Polymer Materials; School of Materials Science and Engineering; Jiangsu University; 301 Xuefu Road Zhenjiang 212013 China
| | - Wenming Yang
- Institute of Polymer Materials; School of Materials Science and Engineering; Jiangsu University; 301 Xuefu Road Zhenjiang 212013 China
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23
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Li SJ, Xie SJ, Li YC, Qian HJ, Lu ZY. Influence of molecular-weight polydispersity on the glass transition of polymers. Phys Rev E 2016; 93:012613. [PMID: 26871128 DOI: 10.1103/physreve.93.012613] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Indexed: 06/05/2023]
Abstract
It is well known that the polymer glass transition temperature T_{g} is dependent on molecular weight, but the role of molecular-weight polydispersity on T_{g} is unclear. Using molecular-dynamics simulations, we clarify that for polymers with the same number-average molecular weight, the molecular-weight distribution profile (either in Schulz-Zimm form or in bimodal form) has very little influence on the glass transition temperature T_{g}, the average segment dynamics (monomer motion, bond orientation relaxation, and torsion transition), and the relaxation-time spectrum, which are related to the local nature of the glass transition. By analyzing monomer motions in different chains, we find that the motion distribution of monomers is altered by molecular-weight polydispersity. Molecular-weight polydispersity dramatically enhances the dynamic heterogeneity of monomer diffusive motions after breaking out of the "cage," but it has a weak influence on the dynamic heterogeneity of the short time scales and the transient spatial correlation between temporarily localized monomers. The stringlike cooperative motion is also not influenced by molecular-weight polydispersity, supporting the idea that stringlike collective motion is not strongly correlated with chain connectivity.
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Affiliation(s)
- Shu-Jia Li
- Institute of Theoretical Chemistry, State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130021, China
| | - Shi-Jie Xie
- Institute of Theoretical Chemistry, State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130021, China
| | - Yan-Chun Li
- Institute of Theoretical Chemistry, State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130021, China
| | - Hu-Jun Qian
- Institute of Theoretical Chemistry, State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130021, China
| | - Zhong-Yuan Lu
- Institute of Theoretical Chemistry, State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130021, China
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Xu WS, Freed KF. Generalized Entropy Theory of Glass Formation in Polymer Melts with Specific Interactions. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b00144] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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