1
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Phan AD, Schweizer KS. Effect of the nature of the solid substrate on spatially heterogeneous activated dynamics in glass forming supported films. J Chem Phys 2024; 160:074902. [PMID: 38364012 DOI: 10.1063/5.0188016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Accepted: 01/10/2024] [Indexed: 02/18/2024] Open
Abstract
We extend the force-level elastically collective nonlinear Langevin equation theory to treat the spatial gradients of the alpha relaxation time and glass transition temperature, and the corresponding film-averaged quantities, to the geometrically asymmetric case of finite thickness supported films with variable fluid-substrate coupling. The latter typically nonuniversally slows down motion near the solid-liquid interface as modeled via modification of the surface dynamic free energy caging constraints that are spatially transferred into the film and which compete with the accelerated relaxation gradient induced by the vapor interface. Quantitative applications to the foundational hard sphere fluid and a polymer melt are presented. The strength of the effective fluid-substrate coupling has very large consequences for the dynamical gradients and film-averaged quantities in a film thickness and thermodynamic state dependent manner. The interference of the dynamical gradients of opposite nature emanating from the vapor and solid interfaces is determined, including the conditions for the disappearance of a bulk-like region in the film center. The relative importance of surface-induced modification of local caging vs the generic truncation of the long range collective elastic component of the activation barrier is studied. The conditions for the accuracy and failure of a simple superposition approximation for dynamical gradients in thin films are also determined. The emergence of near substrate dead layers, large gradient effects on film-averaged response functions, and a weak non-monotonic evolution of dynamic gradients in thick and cold films are briefly discussed. The connection of our theoretical results to simulations and experiments is briefly discussed, as is the extension to treat more complex glass-forming systems under nanoconfinement.
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Affiliation(s)
- Anh D Phan
- Faculty of Materials Science and Engineering, Phenikaa University, Hanoi 12116, Vietnam
- Phenikaa Institute for Advanced Study, Phenikaa University, Hanoi 12116, Vietnam
| | - Kenneth S Schweizer
- Departments of Materials Science, Chemistry, Chemical and Biomolecular Engineering and Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
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2
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Hartley AD, Drayer WF, Ghanekarade A, Simmons DS. Interplay between dynamic heterogeneity and interfacial gradients in a model polymer film. J Chem Phys 2023; 159:204905. [PMID: 38032012 DOI: 10.1063/5.0165650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Glass-forming liquids exhibit long-lived, spatially correlated dynamical heterogeneity, in which some nm-scale regions in the fluid relax more slowly than others. In the nanoscale vicinity of an interface, glass-formers also exhibit the emergence of massive interfacial gradients in glass transition temperature Tg and relaxation time τ. Both of these forms of heterogeneity have a major impact on material properties. Nevertheless, their interplay has remained poorly understood. Here, we employ molecular dynamics simulations of polymer thin films in the isoconfigurational ensemble in order to probe how bulk dynamic heterogeneity alters and is altered by the large gradient in dynamics at the surface of a glass-forming liquid. Results indicate that the τ spectrum at the surface is broader than in the bulk despite being shifted to shorter times, and yet it is less spatially correlated. This is distinct from the bulk, where the τ distribution becomes broader and more spatially organized as the mean τ increases. We also find that surface gradients in slow dynamics extend further into the film than those in fast dynamics-a result with implications for how distinct properties are perturbed near an interface. None of these features track locally with changes in the heterogeneity of caging scale, emphasizing the local disconnect between these quantities near interfaces. These results are at odds with conceptions of the surface as reflecting simply a higher "rheological temperature" than the bulk, instead pointing to a complex interplay between bulk dynamic heterogeneity and spatially organized dynamical gradients at interfaces in glass-forming liquids.
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Affiliation(s)
- Austin D Hartley
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
| | - William F Drayer
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
| | - Asieh Ghanekarade
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
| | - David S Simmons
- Department of Chemical, Biological, and Materials Engineering, The University of South Florida, Tampa, Florida 33620, USA
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3
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Missale E, Frasconi M, Pantano MF. Ultrathin organic membranes: Can they sustain the quest for mechanically robust device applications? iScience 2023; 26:105924. [PMID: 36866039 PMCID: PMC9971879 DOI: 10.1016/j.isci.2023.105924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Ultrathin polymeric films have recently attracted tremendous interest as functional components of coatings, separation membranes, and sensors, with applications spanning from environment-related processes to soft robotics and wearable devices. In order to support the development of robust devices with advanced performances, it is necessary to achieve a deep comprehension of the mechanical properties of ultrathin polymeric films, which can be significantly affected by confinement effects at the nanoscale. In this review paper, we collect the most recent advances in the development of ultrathin organic membranes with emphasis on the relationship between their structure and mechanical properties. We provide the reader with a critical overview of the main approaches for the preparation of ultrathin polymeric films, the methodologies for the investigation of their mechanical properties, and models to understand the primary effects that impact their mechanical response, followed by a discussion on the current trends for designing mechanically robust organic membranes.
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Affiliation(s)
- Elena Missale
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy
| | - Marco Frasconi
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy
- Corresponding author
| | - Maria F. Pantano
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy
- Corresponding author
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4
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Ghanekarade A, Simmons DS. Combined Mixing and Dynamical Origins of Tg Alterations Near Polymer–Polymer Interfaces. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Asieh Ghanekarade
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, Florida33544, United States
| | - David S. Simmons
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, Florida33544, United States
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5
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Wang A, Vargas-Lara F, Younker JM, Iyer KA, Shull KR, Keten S. Quantifying Chemical Composition and Cross-link Effects on EPDM Elastomer Viscoelasticity with Molecular Dynamics. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00162] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Jarod M. Younker
- ExxonMobil Chemical Company, Baytown, Texas 77520, United States
| | - Krishnan A. Iyer
- ExxonMobil Chemical Company, Baytown, Texas 77520, United States
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6
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DeFelice J, Lipson JEG. The influence of additives on polymer matrix mobility and the glass transition. SOFT MATTER 2021; 17:376-387. [PMID: 33169780 DOI: 10.1039/d0sm01634a] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In the region near an interface, the microscopic properties of a glass forming liquid may be perturbed from their equilibrium bulk values. In this work, we probe how the interfacial effects of additive particles dispersed in a matrix can influence the local mobility of the material and its glass transition temperature, Tg. Experimental measurements and simulation results indicate that additives, such as nanoparticles, gas molecules, and oligomers, can shift the mobility and Tg of a surrounding polymer matrix (even for relatively small concentrations of additive; e.g., 5-10% by volume) relative to the pure bulk matrix, thus leading to Tg enhancement or suppression. Additives thus provide a potential route for modifying the properties of a polymer material without significantly changing its chemical composition. Here we apply the Limited Mobility (LM) model to simulate a matrix containing additive species. We show that both additive concentration, as well as the strength of its very local influence on the surrounding matrix material, will determine whether the Tg of the system is raised or lowered, relative to the pure matrix. We demonstrate that incorporation of additives into the simple LM simulation method, which has successfully described the behavior of bulk and thin film glassy solids, leads to direct connections with available experimental and simulation results for a broad range of polymer/additive systems.
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Affiliation(s)
- Jeffrey DeFelice
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA.
| | - Jane E G Lipson
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA.
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7
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Affiliation(s)
- Shuang Jin
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409, United States
| | - Gregory B. McKenna
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409, United States
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8
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Bailey EJ, Tyagi M, Winey KI. Correlation between backbone and pyridine dynamics in poly(
2‐vinyl
pyridine)/silica polymer nanocomposites. JOURNAL OF POLYMER SCIENCE 2020. [DOI: 10.1002/pol.20200416] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Eric J. Bailey
- Department of Materials Science and Engineering University of Pennsylvania Philadelphia Pennsylvania USA
| | - Madhusudan Tyagi
- Center for Neutron Research National Institute of Standards and Technology Gaithersburg Maryland USA
- Department of Materials Science and Engineering University of Maryland College Park Maryland USA
| | - Karen I. Winey
- Department of Materials Science and Engineering University of Pennsylvania Philadelphia Pennsylvania USA
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9
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Higaki Y, Kobayashi M, Takahara A. Hydration State Variation of Polyzwitterion Brushes through Interplay with Ions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:9015-9024. [PMID: 32677837 DOI: 10.1021/acs.langmuir.0c01672] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Polyzwitterions have emerged as a new class of antifouling materials alternating poly(ethylene glycol). The exemplary biopassivation and lubrication behaviors are often attributed to the particular chemical structure of zwitterions, which involve a large dipole moment of the charged groups and a neutral net charge, while the hydration state and dynamics also associate with these characteristics. Polymer brushes composed of surface-tethered polyzwitterion chains produced by surface-initiated controlled radical polymerization have been developed as thin films which exhibit excellent antifouling and lubrication properties. In past decades, numerous studies have been devoted to examining the structure and dynamics of polyzwitterion brush chains in aqueous solutions. This feature article provides an overview of recent studies exploring the hydration state of polyzwitterion brushes with specular neutron reflectivity, highlights some newly published work on the nonuniform equilibrium structure, ion concentration dependence, ion specificity, and the effects of charge spacer length in the zwitterions, and discusses future perspective in this field.
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Affiliation(s)
- Yuji Higaki
- Department of Integrated Science and Technology, Faculty of Science and Technology, Oita University, 700 Dannoharu, Oita 870-1192, Japan
| | - Motoyasu Kobayashi
- School of Advanced Engineering, Kogakuin University, Tokyo 192-0015, Japan
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10
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Diaz Vela D, Ghanekarade A, Simmons DS. Probing the Metrology and Chemistry Dependences of the Onset Condition of Strong “Nanoconfinement” Effects on Dynamics. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b02693] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Daniel Diaz Vela
- Department of Chemical and Biomedical Engineering, The University of South Florida, Tampa, Florida 33620, United States
| | - Asieh Ghanekarade
- Department of Chemical and Biomedical Engineering, The University of South Florida, Tampa, Florida 33620, United States
| | - David S. Simmons
- Department of Chemical and Biomedical Engineering, The University of South Florida, Tampa, Florida 33620, United States
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11
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Experimental evidence on the effect of substrate roughness on segmental dynamics of confined polymer films. POLYMER 2020. [DOI: 10.1016/j.polymer.2020.122501] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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12
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Bailey EJ, Winey KI. Dynamics of polymer segments, polymer chains, and nanoparticles in polymer nanocomposite melts: A review. Prog Polym Sci 2020. [DOI: 10.1016/j.progpolymsci.2020.101242] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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13
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Schweizer KS, Simmons DS. Progress towards a phenomenological picture and theoretical understanding of glassy dynamics and vitrification near interfaces and under nanoconfinement. J Chem Phys 2019; 151:240901. [PMID: 31893888 DOI: 10.1063/1.5129405] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The nature of alterations to dynamics and vitrification in the nanoscale vicinity of interfaces-commonly referred to as "nanoconfinement" effects on the glass transition-has been an open question for a quarter century. We first analyze experimental and simulation results over the last decade to construct an overall phenomenological picture. Key features include the following: after a metrology- and chemistry-dependent onset, near-interface relaxation times obey a fractional power law decoupling relation with bulk relaxation; relaxation times vary in a double-exponential manner with distance from the interface, with an intrinsic dynamical length scale appearing to saturate at low temperatures; the activation barrier and vitrification temperature Tg approach bulk behavior in a spatially exponential manner; and all these behaviors depend quantitatively on the nature of the interface. We demonstrate that the thickness dependence of film-averaged Tg for individual systems provides a poor basis for discrimination between different theories, and thus we assess their merits based on the above dynamical gradient properties. Entropy-based theories appear to exhibit significant inconsistencies with the phenomenology. Diverse free-volume-motivated theories vary in their agreement with observations, with approaches invoking cooperative motion exhibiting the most promise. The elastically cooperative nonlinear Langevin equation theory appears to capture the largest portion of the phenomenology, although important aspects remain to be addressed. A full theoretical understanding requires improved confrontation with simulations and experiments that probe spatially heterogeneous dynamics within the accessible 1-ps to 1-year time window, minimal use of adjustable parameters, and recognition of the rich quantitative dependence on chemistry and interface.
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Affiliation(s)
- Kenneth S Schweizer
- Departments of Materials Science, Chemistry and Chemical & Biomolecular Engineering, Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801, USA
| | - David S Simmons
- Department of Chemical and Biomedical Engineering, University of South Florida, Tampa, Florida 33620, USA
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14
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Xia W, Lan T. Interfacial Dynamics Governs the Mechanical Properties of Glassy Polymer Thin Films. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01235] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wenjie Xia
- Department of Civil & Environmental Engineering, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Tian Lan
- Formulation, Automation & Materials Science, Core R&D, The Dow Chemical Company, 400 Arcola Rd., Collegeville, Pennsylvania 19426, United States
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15
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Shi M, Yang W, Zhang Y, Tan J, Cheng L, Jiao Z, Zhen X. Mechanical and dielectric properties and crystalline behavior of multilayer graphite‐filled polyethylene composites. J Appl Polym Sci 2019. [DOI: 10.1002/app.48131] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Meinong Shi
- College of Mechanical and Electrical EngineeringBeijing University of Chemical Technology Beijing 100029 People's Republic of China
| | - Weimin Yang
- College of Mechanical and Electrical EngineeringBeijing University of Chemical Technology Beijing 100029 People's Republic of China
| | - Youchen Zhang
- College of Mechanical and Electrical EngineeringBeijing University of Chemical Technology Beijing 100029 People's Republic of China
| | - Jing Tan
- College of Mechanical and Electrical EngineeringBeijing University of Chemical Technology Beijing 100029 People's Republic of China
| | - Lisheng Cheng
- College of Mechanical and Electrical EngineeringBeijing University of Chemical Technology Beijing 100029 People's Republic of China
| | - Zhiwei Jiao
- College of Mechanical and Electrical EngineeringBeijing University of Chemical Technology Beijing 100029 People's Republic of China
| | - Xiangshi Zhen
- College of Mechanical and Electrical EngineeringBeijing University of Chemical Technology Beijing 100029 People's Republic of China
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16
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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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17
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A ND, Begam N, Ibrahim M, Chandran S, Padmanabhan V, Sprung M, Basu JK. Viscosity and fragility of confined polymer nanocomposites: a tale of two interfaces. NANOSCALE 2019; 11:8546-8553. [PMID: 30990482 DOI: 10.1039/c8nr10362c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Viscosity and fragility are key parameters determining the processability and thermo-mechanical stability of glassy polymers and polymer nanocomposites (PNCs). In confined polymers, these parameters are largely dominated by the long relaxation times of the polymers adsorbed at the substrate-polymer interface. On the other hand, for polymer nanocomposites, the interface layer (IL) between the nanoparticles and the surrounding matrix chains often control not only the morphology and dispersion but also various parameters like viscosity and glass transition temperature. Confined PNCs, hence, present a unique opportunity to study the interplay of these two independent interfacial effects. Here, we report the results of X-ray scattering based dynamics measurements of PNC thin films, with a two IL width, unraveling the subtle interplay of these two interfaces on the measured viscosity and fragility. Coupled with coarse-grained molecular dynamics (MD) simulations, our experimental results demonstrate that the viscosity of the PNC films increases with both the IL width and the thickness of the polymer layer adsorbed at the substrate interface. However, while both pristine PS and PNCs with a higher IL width become stronger glasses, as estimated by their fragility, the PNC with a lower IL width shows an increase in fragility with increasing confinement. Our results suggest a novel method to control thermo-mechanical properties and stability of PNC coatings by independently controlling the two interfacial effects in athermal glassy PNCs.
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Affiliation(s)
- Nimmi Das A
- Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
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18
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Bailey EJ, Griffin PJ, Tyagi M, Winey KI. Segmental Diffusion in Attractive Polymer Nanocomposites: A Quasi-Elastic Neutron Scattering Study. Macromolecules 2019. [DOI: 10.1021/acs.macromol.8b01716] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Eric J. Bailey
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Philip J. Griffin
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Madhusudan Tyagi
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Karen I. Winey
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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19
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Lewis EA, Stafford CM, Vogt BD. Effect of Adjacent Hydrophilic Polymer Thin Films on Physical Aging and Residual Stress in Thin Films of Poly(butylnorbornene- ran-hydroxyhexafluoroisopropyl norbornene). JOURNAL OF POLYMER SCIENCE. PART B, POLYMER PHYSICS 2019; 57:10.1002/polb.24855. [PMID: 32165786 PMCID: PMC7067284 DOI: 10.1002/polb.24855] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 06/03/2019] [Indexed: 11/10/2022]
Abstract
The properties of thin supported polymer films can be dramatically impacted by the substrate upon which it resides. A simple way to alter the properties of the substrate (chemistry, rigidity, dynamics) is by coating it with an immiscible polymer. Here we describe how ultrathin (ca. 2 nm) hydrophilic polymer layers of poly(acrylic acid), PAA, and poly(styrenesulfonate), PSS, impact the aging behavior and the residual stress in thin films of poly(butylnorbornene-ran-hydroxyhexafluoroisopropyl norbornene), BuNB-r-HFANB. The aging rate decreases as the film thickness (h) is decreased, but the extent of this change depends on the adjacent layer. Even for the thickest films (h>500 nm), there is a decrease in the aging rate at 100 °C when BuNB-r-HFANB is in contact with PSS. In an effort to understand the origins of these differences in the aging behavior, the elastic modulus and residual stress (σR) in the films were determined by wrinkling as a function of aging time. The change in the elastic modulus during aging does not appear to be directly correlated with the densification or expansion of the films, but the aging rates appear to roughly scale as hσR 1/3. These results illustrate that the physical aging of thin polymer films can be altered by adjacent polymers.
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Affiliation(s)
- Elizabeth A Lewis
- Department of Polymer Engineering, University of Akron, Akron, OH 44325 USA
| | - Christopher M Stafford
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
| | - Bryan D Vogt
- Department of Polymer Engineering, University of Akron, Akron, OH 44325 USA
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20
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Diaz-Vela D, Hung JH, Simmons DS. Temperature-Independent Rescaling of the Local Activation Barrier Drives Free Surface Nanoconfinement Effects on Segmental-Scale Translational Dynamics near Tg. ACS Macro Lett 2018; 7:1295-1301. [PMID: 35651251 DOI: 10.1021/acsmacrolett.8b00695] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Near-interface alterations in dynamics and glass formation behavior have been the subject of extensive study for the past two decades, both because of their practical importance and in the hope of revealing underlying correlation lengths underpinning glass transition more generally. Here we employ molecular dynamics simulations of thick films to demonstrate that these effects emerge, for segmental-scale translational dynamics at low temperature, from a temperature-independent rescaling of the local activation barrier. This rescaling manifests as a fractional power law decoupling relationship of local dynamics relative to the bulk, with a transition from a regime of weak decoupling at high temperatures to a regime of strong decoupling at low temperatures. The range of this effect saturates at low temperatures, with 90% of the surface perturbation in the barrier lost over a range of 12 segmental diameters. These findings reduce the phenomenology of Tg nanoconfinement effects to two properties-a position-dependent, temperature independent, barrier rescaling factor and an onset time scale-while substantially constraining the predictions required from any theoretical explanation of this phenomenon.
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Affiliation(s)
- Daniel Diaz-Vela
- The University of Akron, 250 South Forge Street, Akron, Ohio 44325, United States
| | - Jui-Hsiang Hung
- The University of Akron, 250 South Forge Street, Akron, Ohio 44325, United States
| | - David S. Simmons
- The University of South Florida, 4202 East Fowler Avenue, ENB 118, Tampa, Florida 33620, United States
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21
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Katsumata R, Dulaney AR, Kim CB, Ellison CJ. Glass Transition and Self-Diffusion of Unentangled Polymer Melts Nanoconfined by Different Interfaces. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b00475] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Reika Katsumata
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Austin R. Dulaney
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Chae Bin Kim
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Christopher J. Ellison
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Department of Chemical Engineering and Materials Science, The University of Minnesota - Twin Cities, Minneapolis, Minnesota 55455, United States
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22
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Phan AD, Schweizer KS. Elastically Collective Nonlinear Langevin Equation Theory of Glass-Forming Liquids: Transient Localization, Thermodynamic Mapping, and Cooperativity. J Phys Chem B 2018; 122:8451-8461. [DOI: 10.1021/acs.jpcb.8b04975] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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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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24
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Inoue R, Kanaya T, Yamada T, Shibata K, Fukao K. Experimental investigation of the glass transition of polystyrene thin films in a broad frequency range. Phys Rev E 2018; 97:012501. [PMID: 29448351 DOI: 10.1103/physreve.97.012501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Indexed: 11/07/2022]
Abstract
In this study, we investigate the α process of a polystyrene thin film using inelastic neutron scattering (INS), dielectric relaxation spectroscopy (DRS), and thermal expansion spectroscopy (TES). The DRS and TES measurements exhibited a decrease in glass transition temperature (T_{g}) with film thickness. On the other hand, an increase in T_{g} was observed in INS studies. In order to interpret this contradiction, we investigated the temperature dependence of the peak frequency (f_{m}) of the α process probed by DRS and TES. The experiments revealed an increase in the peak frequency (f_{m}) with decreasing film thickness in the frequency region. This observation is consistent with the observed decrease in T_{g} with thickness. Interestingly, the increase in T_{g} with film thickness was confirmed by fitting the temperature dependence measurements of the peak frequency with the Vogel-Fulcher-Tammann equation, within the frequency region probed by INS. The discrepancy between INS and DRS or TES descriptions of the α process is likely to be attributed to a decrease in the apparent activation energy with film thickness and reduced mobility, due to the impenetrable wall effect.
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Affiliation(s)
- Rintaro Inoue
- Research Reactor Institute, Kyoto University, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Toshiji Kanaya
- J-PARC, Material and Life Science Division, Institute of Material Structure Science, High Energy Accelerator Research Organization (KEK), 203-1 Shirakata, Tokai-mura, Naka-gun, Ibaraki, 319-1106, Japan
| | - Takeshi Yamada
- CROSS-Tokai, Research Center for Neutron Science and Technology, Tokai, Ibaraki 319-1106, Japan
| | - Kaoru Shibata
- Neutron Science Section, J-PARC Center, Tokai, Ibaraki 319-1195, Japan
| | - Koji Fukao
- Department of Physics, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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25
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Sugimoto S, Inutsuka M, Kawaguchi D, Tanaka K. Reorientation Kinetics of Local Conformation of Polyisoprene at Substrate Interface. ACS Macro Lett 2018; 7:85-89. [PMID: 35610922 DOI: 10.1021/acsmacrolett.7b00927] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The performance of a polymer composite material, in which inorganic fillers are dispersed, is closely related to the aggregation states and dynamics of polymer chains at the interface with the filler. In this study, the local conformation of polyisoprene (PI) at a quartz substrate interface was studied as a model system for the rubber/filler composite material. PI films were prepared from a toluene solution onto quartz substrates by a spin-coating method. Sum-frequency generation spectroscopy revealed that the local conformation of PI chains at the quartz interface depended on the spinning rate. The tilt angle of methyl groups increased with the rotational speed, probably due to the centrifugal force applied to chains and probably also the evaporation rate of the solvent during the solidification process. This result indicates that the interfacial orientation of PI chains can remain even at room temperature, which is 87 K higher than the bulk glass transition temperature (Tgb). The interfacial orientation disappeared at a temperature approximately 120 K higher than Tgb.
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Affiliation(s)
- Shin Sugimoto
- Department
of Automotive Science, ‡Department of Applied Chemistry, §Education Center for
Global Leaders in Molecular Systems for Devices, and ∥International Institute for Carbon-Neutral
Energy Research (WPI-I2CNER), Kyushu University, Fukuoka, 819-0395, Japan
| | - Manabu Inutsuka
- Department
of Automotive Science, ‡Department of Applied Chemistry, §Education Center for
Global Leaders in Molecular Systems for Devices, and ∥International Institute for Carbon-Neutral
Energy Research (WPI-I2CNER), Kyushu University, Fukuoka, 819-0395, Japan
| | - Daisuke Kawaguchi
- Department
of Automotive Science, ‡Department of Applied Chemistry, §Education Center for
Global Leaders in Molecular Systems for Devices, and ∥International Institute for Carbon-Neutral
Energy Research (WPI-I2CNER), Kyushu University, Fukuoka, 819-0395, Japan
| | - Keiji Tanaka
- Department
of Automotive Science, ‡Department of Applied Chemistry, §Education Center for
Global Leaders in Molecular Systems for Devices, and ∥International Institute for Carbon-Neutral
Energy Research (WPI-I2CNER), Kyushu University, Fukuoka, 819-0395, Japan
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26
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Cangialosi D. Glass Transition and Physical Aging of Confined Polymers Investigated by Calorimetric Techniques. RECENT ADVANCES, TECHNIQUES AND APPLICATIONS 2018. [DOI: 10.1016/b978-0-444-64062-8.00013-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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27
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Xia W, Song J, Jeong C, Hsu DD, Phelan FR, Douglas JF, Keten S. Energy-Renormalization for Achieving Temperature Transferable Coarse-Graining of Polymer Dynamics. Macromolecules 2017; 50. [PMID: 30996475 DOI: 10.1021/acs.macromol.7b01717] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The bottom-up prediction of the properties of polymeric materials based on molecular dynamics simulation is a major challenge in soft matter physics. Coarse-grained (CG) models are often employed to access greater spatiotemporal scales required for many applications, but these models normally experience significantly altered thermodynamics and highly accelerated dynamics due to the reduced number of degrees of freedom upon coarse-graining. While CG models can be calibrated to meet certain properties at particular state points, there is unfortunately no temperature transferable and chemically specific coarse-graining method that allows for modeling of polymer dynamics over a wide temperature range. Here, we pragmatically address this problem by "correcting" for deviations in activation free energies that occur upon coarse-graining the dynamics of a model polymeric material (polystyrene). In particular, we propose a new strategy based on concepts drawn from the Adam-Gibbs (AG) theory of glass formation. Namely we renormalize the cohesive interaction strength and effective interaction length-scale parameters to modify the activation free energy. We show that this energy-renormalization method for CG modeling allows accurate prediction of atomistic dynamics over the Arrhenius regime, the non-Arrhenius regime of glass formation, and even the non-equilibrium glassy regime, thus allowing for the predictive modeling of dynamic properties of polymer over the entire range of glass formation. Our work provides a practical scheme for establishing temperature transferable coarse-grained models for predicting and designing the properties of polymeric materials.
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Affiliation(s)
- Wenjie Xia
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States.,Department of Civil & Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States.,Center for Hierarchical Materials Design, Northwestern University, Evanston, Illinois 60208-3109, United States
| | - Jake Song
- Department of Materials Science & Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - Cheol Jeong
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - David D Hsu
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - Frederick R Phelan
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Jack F Douglas
- Materials Science & Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Sinan Keten
- Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States.,Department of Civil & Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
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28
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Vogt BD. Mechanical and viscoelastic properties of confined amorphous polymers. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/polb.24529] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Bryan D. Vogt
- Department of Polymer Engineering; University of Akron; Akron Ohio 44325
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29
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Zhou Y, Milner ST. Short-Time Dynamics Reveals Tg Suppression in Simulated Polystyrene Thin Films. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00921] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Yuxing Zhou
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Scott T. Milner
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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30
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Zhang M, Askar S, Torkelson JM, Brinson LC. Stiffness Gradients in Glassy Polymer Model Nanocomposites: Comparisons of Quantitative Characterization by Fluorescence Spectroscopy and Atomic Force Microscopy. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00917] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Min Zhang
- Department
of Materials Science and Engineering, ‡Department of Chemical and Biological
Engineering, and §Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Shadid Askar
- Department
of Materials Science and Engineering, ‡Department of Chemical and Biological
Engineering, and §Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - John M. Torkelson
- Department
of Materials Science and Engineering, ‡Department of Chemical and Biological
Engineering, and §Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - L. Catherine Brinson
- Department
of Materials Science and Engineering, ‡Department of Chemical and Biological
Engineering, and §Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, United States
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31
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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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32
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Kushner DI, Hickner MA. Water Sorption in Electron-Beam Evaporated SiO 2 on QCM Crystals and Its Influence on Polymer Thin Film Hydration Measurements. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5261-5268. [PMID: 28474891 DOI: 10.1021/acs.langmuir.7b00759] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Spectroscopic ellipsometry (SE) and quartz crystal microbalance (QCM) measurements are two critical characterization techniques routinely employed for hydration studies of polymer thin films. Water uptake by thin polymer films is an important area of study to investigate antifouling surfaces, to probe the swelling of thin water-containing ionomer films, and to conduct fundamental studies of polymer brush hydration and swelling. SiO2-coated QCM crystals, employed as substrates in many of these hydration studies, show porosity in the thin electron-beam (e-beam) evaporated SiO2 layer. The water sorption into this porous SiO2 layer requires correction of the optical and mass characterization of the hydrated polymer due to changes in the SiO2 layer as it sorbs water. This correction is especially important when experiments on SiO2-coated QCM crystals are compared to measurements on Si wafers with dense native SiO2 layers. Water adsorption filling void space during hydration in ∼200-260 nm thick SiO2 layers deposited on a QCM crystal resulted in increased refractive index of the layer during water uptake experiments. The increased refractive index led to artificially higher polymer swelling in the optical modeling of the hydration experiments. The SiO2-coated QCM crystals showed between 6 and 8% void as measured by QCM and SE, accounting for 60%-85% of the measured polymer swelling in the low humidity regime (<20% RH) and 25%-40% of the polymer swelling in the high humidity regime (>70% RH) from optical modeling for 105 and 47 nm thick sulfonated polymer films. Correcting the refractive index of the SiO2 layer for its water content resulted in polymer swelling that successfully resembled swelling measured on a silicon wafer with nonporous native oxide.
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Affiliation(s)
- Douglas I Kushner
- Department of Materials Science and Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Michael A Hickner
- Department of Materials Science and Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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33
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Mangalara JH, Mackura ME, Marvin MD, Simmons DS. The relationship between dynamic and pseudo-thermodynamic measures of the glass transition temperature in nanostructured materials. J Chem Phys 2017; 146:203316. [DOI: 10.1063/1.4977520] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Jayachandra Hari Mangalara
- Department of Polymer Engineering, The University of Akron, 250 South Forge St, Akron, Ohio, 44325-0301 USA
| | - Mark E. Mackura
- Department of Polymer Engineering, The University of Akron, 250 South Forge St, Akron, Ohio, 44325-0301 USA
| | - Michael D. Marvin
- Department of Polymer Engineering, The University of Akron, 250 South Forge St, Akron, Ohio, 44325-0301 USA
| | - David S. Simmons
- Department of Polymer Engineering, The University of Akron, 250 South Forge St, Akron, Ohio, 44325-0301 USA
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34
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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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35
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Napolitano S, Glynos E, Tito NB. Glass transition of polymers in bulk, confined geometries, and near interfaces. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:036602. [PMID: 28134134 DOI: 10.1088/1361-6633/aa5284] [Citation(s) in RCA: 244] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
When cooled or pressurized, polymer melts exhibit a tremendous reduction in molecular mobility. If the process is performed at a constant rate, the structural relaxation time of the liquid eventually exceeds the time allowed for equilibration. This brings the system out of equilibrium, and the liquid is operationally defined as a glass-a solid lacking long-range order. Despite almost 100 years of research on the (liquid/)glass transition, it is not yet clear which molecular mechanisms are responsible for the unique slow-down in molecular dynamics. In this review, we first introduce the reader to experimental methodologies, theories, and simulations of glassy polymer dynamics and vitrification. We then analyse the impact of connectivity, structure, and chain environment on molecular motion at the length scale of a few monomers, as well as how macromolecular architecture affects the glass transition of non-linear polymers. We then discuss a revised picture of nanoconfinement, going beyond a simple picture based on interfacial interactions and surface/volume ratio. Analysis of a large body of experimental evidence, results from molecular simulations, and predictions from theory supports, instead, a more complex framework where other parameters are relevant. We focus discussion specifically on local order, free volume, irreversible chain adsorption, the Debye-Waller factor of confined and confining media, chain rigidity, and the absolute value of the vitrification temperature. We end by highlighting the molecular origin of distributions in relaxation times and glass transition temperatures which exceed, by far, the size of a chain. Fast relaxation modes, almost universally present at the free surface between polymer and air, are also remarked upon. These modes relax at rates far larger than those characteristic of glassy dynamics in bulk. We speculate on how these may be a signature of unique relaxation processes occurring in confined or heterogeneous polymeric systems.
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Affiliation(s)
- Simone Napolitano
- Laboratory of Polymer and Soft Matter Dynamics, Faculté des Sciences, Université Libre de Bruxelles (ULB), Boulevard du Triomphe, 1050 Brussels, Belgium
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36
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Zhang L, Elupula R, Grayson SM, Torkelson JM. Suppression of the Fragility-Confinement Effect via Low Molecular Weight Cyclic or Ring Polymer Topology. Macromolecules 2017. [DOI: 10.1021/acs.macromol.6b02280] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
| | - Ravinder Elupula
- Department
of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Scott M. Grayson
- Department
of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
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37
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Geng K, Katsumata R, Yu X, Ha H, Dulaney AR, Ellison CJ, Tsui OKC. Conflicting Confinement Effects on the Tg, Diffusivity, and Effective Viscosity of Polymer Films: A Case Study with Poly(isobutyl methacrylate) on Silica and Possible Resolution. Macromolecules 2017. [DOI: 10.1021/acs.macromol.6b01354] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
| | - Reika Katsumata
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | | | - Heonjoo Ha
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Austin R. Dulaney
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Christopher J. Ellison
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
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38
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Shi M, Zhang Y, Cheng L, Jiao Z, Yang W, Tan J, Ding Y. Interfacial Diffusion and Bonding in Multilayer Polymer Films: A Molecular Dynamics Simulation. J Phys Chem B 2016; 120:10018-29. [PMID: 27556140 DOI: 10.1021/acs.jpcb.6b04471] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
As a stacked form of ultrathin polymer films, multilayer nanostructures are of great interest in various applications. Coarse-grained molecular dynamics simulations were carried out to understand the behaviors of interfacial diffusion and bonding of multilayer polymer films. We found two obvious stages for the interfacial diffusion of polymers in the multilayer film, and it is 3 times faster in the first stage than in the second one due to the evolution of molecular conformations. The polymers near the interfaces have an in-plane mobility much higher than the out-of-plane one. The strength of interfacial bonding has been characterized by the fast tensile stress-strain curve along the normal direction. It shows multiple yielding points for the multilayer polymer films, which is distinct from the tensile behavior of the bulk. The ultimate tensile stress (UTS) and corresponding separating strain, surprisingly, do not necessarily increase with diffusion time. Because of the dramatic molecular rotation and extension during the first stage of interfacial diffusion, the interlayer interpenetration is nonuniformly distributed in the plane of the interface. Such a nonuniform distribution may be one of the reasons for the decrease of the UTS and separating strain.
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Affiliation(s)
- Meinong Shi
- College of Mechanical and Electrical Engineering and ‡State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology , Beijing 100029, P. R. China
| | - Youchen Zhang
- College of Mechanical and Electrical Engineering and ‡State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology , Beijing 100029, P. R. China
| | - Lisheng Cheng
- College of Mechanical and Electrical Engineering and ‡State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology , Beijing 100029, P. R. China
| | - Zhiwei Jiao
- College of Mechanical and Electrical Engineering and ‡State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology , Beijing 100029, P. R. China
| | - Weimin Yang
- College of Mechanical and Electrical Engineering and ‡State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology , Beijing 100029, P. R. China
| | - Jing Tan
- College of Mechanical and Electrical Engineering and ‡State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology , Beijing 100029, P. R. China
| | - Yumei Ding
- College of Mechanical and Electrical Engineering and ‡State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology , Beijing 100029, P. R. China
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39
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Zhang H, Tao K, Liu D, Wu K, Wang F, Yang J, Zhao J. Examining dynamics in a polymer matrix by single molecule fluorescence probes of different sizes. SOFT MATTER 2016; 12:7299-7306. [PMID: 27507703 DOI: 10.1039/c6sm01447j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Rotational motion of single fluorescence probes with different sizes doped inside films of polyvinylacetate is investigated by defocused single molecule fluorescence microscopy. Discrete vibration modes in the rotational motion of individual probes are clearly exposed in the power spectra of the rotation trajectories, reflecting multiple relaxation dynamics and also the difference in dynamics among separate locations. The power spectra show a strong dependence on the probe size and temperature. By sampling the rotation of a large number of probes, the averaged power spectra show that the activated rotation of the probes falls into the frequency range of the α-relaxation and data analysis shows that activation of the vibration modes with all probes corresponds to the maximum population of rotating probes, and this made the comparison between single molecule data and the ensemble data meaningful (differential scanning calorimetry, as an example). Such an analysis shows a coincidence between the temperature of a significant occurrence of glass transition and the activation of rotational motion of all probes with one specific size, indicating that such a dimension correlates with the size of the cooperative rearrangement region - a volume of approximately 1.0 nm(3).
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Affiliation(s)
- Hao Zhang
- Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
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40
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Stiffness of thin, supported polystyrene films: Free-surface, substrate, and confinement effects characterized via self-referencing fluorescence. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.07.042] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Xia W, Song J, Hsu DD, Keten S. Understanding the Interfacial Mechanical Response of Nanoscale Polymer Thin Films via Nanoindentation. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00121] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Wenjie Xia
- Department of Civil & Environmental Engineering, ‡Department of Materials Science & Engineering, and §Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - Jake Song
- Department of Civil & Environmental Engineering, ‡Department of Materials Science & Engineering, and §Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - David D. Hsu
- Department of Civil & Environmental Engineering, ‡Department of Materials Science & Engineering, and §Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
| | - Sinan Keten
- Department of Civil & Environmental Engineering, ‡Department of Materials Science & Engineering, and §Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3109, United States
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42
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43
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DeFelice J, Milner ST, Lipson JEG. Simulating Local Tg Reporting Layers in Glassy Thin Films. Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00090] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Jeffrey DeFelice
- Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States
| | - Scott T. Milner
- Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Jane E. G. Lipson
- Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, United States
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44
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Zhang L, Elupula R, Grayson SM, Torkelson JM. Major Impact of Cyclic Chain Topology on the Tg-Confinement Effect of Supported Thin Films of Polystyrene. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b02474] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
| | - Ravinder Elupula
- Department
of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Scott M. Grayson
- Department
of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
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Affiliation(s)
- David S. Simmons
- Department of Polymer Engineering; University of Akron; 250 South Forge St Akron OH 44325 USA
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Evans CM, Kim S, Roth CB, Priestley RD, Broadbelt LJ, Torkelson JM. Role of neighboring domains in determining the magnitude and direction of Tg-confinement effects in binary, immiscible polymer systems. POLYMER 2015. [DOI: 10.1016/j.polymer.2015.10.059] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Residual stress relaxation and stiffness in spin-coated polymer films: Characterization by ellipsometry and fluorescence. POLYMER 2015. [DOI: 10.1016/j.polymer.2015.08.036] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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