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Omar H, Ahmadi S, Szymoniak P, Schönhals A. Molecular mobility of thin films of poly(bisphenol-A carbonate) capped and with one free surface: from bulk-like samples down to the adsorbed layer. SOFT MATTER 2025; 21:241-254. [PMID: 39655510 DOI: 10.1039/d4sm01238k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2025]
Abstract
The molecular mobility of thin films of poly(bisphenol A carbonate) (PBAC) was systematically investigated using broadband dielectric spectroscopy, employing two distinct electrode configurations. First, films were prepared in a capped geometry between aluminum electrodes employing a crossed electrode capacitor (CEC) configuration, down to film thicknesses of 40 nm. The Vogel temperature, derived from the temperature dependence of relaxation rates of the α-relaxation, increases with decreasing film thickness characterized by an onset thickness. The onset thickness depends on the annealing conditions, with less intense annealing yielding a lower onset thickness. Additionally, a broadening of the β-relaxation peak was observed with decreasing thickness, attributed to the interaction of phenyl groups with thermally evaporated aluminum, resulting in a shift of certain relaxation modes to higher temperatures relative to the bulk material. A novel phenomenon, termed the slow Arrhenius process (SAP), was also identified in proximity to the α-relaxation temperature. For films with thicknesses below 40 nm, nanostructured electrodes (NSE) were utilized, incorporating nanostructured silica spacers to establish a free surface with air. This free surface causes an enhancement in the molecular mobility for the 40 nm sample, preserving the β-relaxation as a distinct peak. The α-relaxation was detectable in the dielectric loss down to 18 nm, shifting to higher temperatures as film thickness is decreased. Notably, the onset thickness for the increase in Vogel temperature was lower in the NSE configuration compared to the CEC setup, attributed to the presence of the polymer-air interface.
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Affiliation(s)
- Hassan Omar
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
| | - Shayan Ahmadi
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
| | - Paulina Szymoniak
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
| | - Andreas Schönhals
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
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Qin H, Liu T, Liu Z, Guo M, Guo Y, Tian M. Insights into multi-scale structural evolution and dielectric response of poly(methyl acrylate) under pre-strain: A simulation study. J Chem Phys 2024; 161:224901. [PMID: 39651816 DOI: 10.1063/5.0238343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2024] [Accepted: 11/25/2024] [Indexed: 12/11/2024] Open
Abstract
The structural evolution of dielectric elastomer induced by pre-strain is a complex, multi-scale process that poses a significant challenge to a deep understanding of the effect of pre-strain. Through simulation results, we identify the variation in the dielectric constant and multi-scale (electronic structure, molecular chain conformation, and aggregation structure) response of poly(methyl acrylate). As the pre-strain increases, the dielectric constant initially rises (below 200% pre-strain) and then declines (above 200% pre-strain). Analysis of the charge distribution, surface electrostatic potential, HOMO-LUMO bandgap, and electron density differences reveal that adjusting chain conformation appropriately could enhance polarity domain and electron polarization. The correlation between permittivity and segment dynamics of deformed molecules is explored, encompassing segment orientation, mean shift displacement, and diffusion coefficient. Following molecular chain orientation, the kinematic capability of the chain segment improves, which leads to an increase in the number and activity of effective dipoles and the enhancement of orientation polarization. Excessive stretching restricts the polymer molecular chain mechanically, reducing the number and activity of effective dipoles and negatively impacting electron polarization. The permittivity transitions from isotropic to anisotropic behavior when the system is subjected to strain. This study provides an interesting solution for research on multiscale responses and intrinsic mechanisms of pre-strain.
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Affiliation(s)
- Han Qin
- Key Laboratory of Computing Power Network and Information Security, Ministry of Education, Shandong Computer Science Center (National Supercomputer Center in Jinan), Qilu University of Technology (Shandong Academy of Sciences), Jinan 250000, China
- Shandong Provincial Key Laboratory of Computing Power Internet and Service Computing, Shandong Fundamental Research Center for Computer Science, Jinan 250000, China
| | - Tao Liu
- Key Laboratory of Computing Power Network and Information Security, Ministry of Education, Shandong Computer Science Center (National Supercomputer Center in Jinan), Qilu University of Technology (Shandong Academy of Sciences), Jinan 250000, China
- Shandong Provincial Key Laboratory of Computing Power Internet and Service Computing, Shandong Fundamental Research Center for Computer Science, Jinan 250000, China
| | - Zhaoyuan Liu
- Key Laboratory of Computing Power Network and Information Security, Ministry of Education, Shandong Computer Science Center (National Supercomputer Center in Jinan), Qilu University of Technology (Shandong Academy of Sciences), Jinan 250000, China
- Shandong Provincial Key Laboratory of Computing Power Internet and Service Computing, Shandong Fundamental Research Center for Computer Science, Jinan 250000, China
| | - Meng Guo
- Key Laboratory of Computing Power Network and Information Security, Ministry of Education, Shandong Computer Science Center (National Supercomputer Center in Jinan), Qilu University of Technology (Shandong Academy of Sciences), Jinan 250000, China
- Shandong Provincial Key Laboratory of Computing Power Internet and Service Computing, Shandong Fundamental Research Center for Computer Science, Jinan 250000, China
| | - Ying Guo
- Key Laboratory of Computing Power Network and Information Security, Ministry of Education, Shandong Computer Science Center (National Supercomputer Center in Jinan), Qilu University of Technology (Shandong Academy of Sciences), Jinan 250000, China
- Shandong Provincial Key Laboratory of Computing Power Internet and Service Computing, Shandong Fundamental Research Center for Computer Science, Jinan 250000, China
| | - Ming Tian
- Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, Beijing 100029, China
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Shimokita K, Yamamoto K, Miyata N, Shibata M, Nakanishi Y, Arakawa M, Takenaka M, Kida T, Tokumitsu K, Tanaka R, Shiono T, Yamada M, Seto H, Yamada NL, Aoki H, Miyazaki T. Neutron Reflectivity Study on the Adsorption Layer of Polyethylene Grown on Si Substrate. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 39012261 DOI: 10.1021/acs.langmuir.4c01584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/17/2024]
Abstract
To investigate the structure of the interface between polyethylene films and substrates, the neutron reflectivity (NR) of deuterated polyethylene (dPE) thin films deposited on Si substrates was measured, demonstrating water accumulation at the interface, even under ambient conditions. After leaching the thermally annealed dPE films in hot p-xylene, NR measurements were conducted on the layers remaining on the substrate, clearly revealing that the adsorption layer of dPE grew during annealing and consisted of two layers, an inner adsorption layer and an outer adsorption layer, as previously proposed for amorphous polymers. The inner adsorption layer was approximately 3.7 nm thick with a density comparable to that of the bulk. The outer adsorption layer was several nanometers thick and appeared to grow insufficiently on top of the inner adsorption layer under the annealing conditions examined in this study. This study clarifying the growth of the adsorption layer of polyethylene at the interface with an inorganic substrate is useful for improving the performance of polymer/inorganic filler nanocomposites due to the wide utility of crystalline polyolefins as polymer matrix materials in nanocomposites.
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Affiliation(s)
- Keisuke Shimokita
- Department of Life Science and Applied Chemistry, Gradual School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Katsuhiro Yamamoto
- Department of Life Science and Applied Chemistry, Gradual School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Noboru Miyata
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Motoki Shibata
- Office of Society-Academia Collaboration for Innovation, Kyoto University, Sakyou-ku, Kyoto 606-8501, Japan
| | - Yohei Nakanishi
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Masato Arakawa
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Mikihito Takenaka
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Takumitsu Kida
- Department of Materials Chemistry, Faculty of Engineering, The University of Shiga Prefecture, 2500 Hassaka, Hikone 522-8533, Japan
| | - Katsuhisa Tokumitsu
- Department of Materials Chemistry, Faculty of Engineering, The University of Shiga Prefecture, 2500 Hassaka, Hikone 522-8533, Japan
| | - Ryo Tanaka
- Graduate School of Advanced Science and Engineering, Applied Chemistry Program, Hiroshima University, 1-4-1 Kagamiyama, Higashi-hiroshima 739-8527, Japan
| | - Takeshi Shiono
- Graduate School of Advanced Science and Engineering, Applied Chemistry Program, Hiroshima University, 1-4-1 Kagamiyama, Higashi-hiroshima 739-8527, Japan
| | - Masako Yamada
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Hideki Seto
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Norifumi L Yamada
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Hiroyuki Aoki
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan
| | - Tsukasa Miyazaki
- Office of Society-Academia Collaboration for Innovation, Kyoto University, Sakyou-ku, Kyoto 606-8501, Japan
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Omar H, Hidde G, Szymoniak P, Hertwig A, Schönhals A. Growth kinetics of the adsorbed layer of poly(bisphenol A carbonate) and its effect on the glass transition behavior in thin films. RSC Adv 2023; 13:14473-14483. [PMID: 37179996 PMCID: PMC10173819 DOI: 10.1039/d3ra02020g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 05/03/2023] [Indexed: 05/15/2023] Open
Abstract
The glass transition behavior of thin films of poly(bisphenol A carbonate) (PBAC) was studied employing ellipsometry. The glass transition temperature increases with the reduction of the film thickness. This result is attributed to the formation of an adsorbed layer with a reduced mobility compared to bulk PBAC. Therefore, for the first time, the growth kinetics of the adsorbed layer of PBAC was investigated, prepared by leaching samples from a 200 nm thin film which were annealed for several times at three different temperatures. The thickness of each prepared adsorbed layer was measured by multiple scans using atomic force microscopy (AFM). Additionally, an unannealed sample was measured. Comparison of the measurements of the unannealed and the annealed samples provides proof of a pre-growth regime for all annealing temperatures which was not observed for other polymers. For the lowest annealing temperature after the pre-growth stage only a growth regime with a linear time dependence is observed. For higher annealing temperatures the growth kinetics changes from a linear to a logarithmic growth regime at a critical time. At the longest annealing times the films showed signs of dewetting where segments of the adsorbed film were removed from the substrate (dewetting by desorption). The dependence of the surface roughness of the PBAC surface on annealing time also confirmed that the films annealed at highest temperatures for the longest times desorbed from the substrate.
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Affiliation(s)
- Hassan Omar
- Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany +49 30/8104-1617 +49 30/8104-3384
| | - Gundula Hidde
- Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany +49 30/8104-1617 +49 30/8104-3384
| | - Paulina Szymoniak
- Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany +49 30/8104-1617 +49 30/8104-3384
| | - Andreas Hertwig
- Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany +49 30/8104-1617 +49 30/8104-3384
| | - Andreas Schönhals
- Bundesanstalt für Materialforschung und -prüfung (BAM) Unter den Eichen 87 12205 Berlin Germany +49 30/8104-1617 +49 30/8104-3384
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Shimokita K, Yamamoto K, Miyata N, Nakanishi Y, Shibata M, Takenaka M, Yamada NL, Seto H, Aoki H, Miyazaki T. Neutron reflectivity study on the nanostructure of PMMA chains near substrate interfaces based on contrast variation accompanied with small molecule sorption. SOFT MATTER 2023; 19:2082-2089. [PMID: 36808205 DOI: 10.1039/d2sm01482c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
In the case of poly(methyl methacrylate) (PMMA) thin films on a Si substrate, thermal annealing induces the formation of a layer of PMMA chains tightly adsorbed near the substrate interface, and the strongly adsorbed PMMA remains on the substrate, even after washing with toluene (hereinafter called adsorbed sample). Neutron reflectometry revealed that the concerned structure consists of three layers: an inner layer (tightly bound on the substrate), a middle layer (bulk-like), and an outer layer (surface) in the adsorbed sample. When an adsorbed sample was exposed to toluene vapor, it became clear that, between the solid adsorption layer (which does not swell) and bulk-like swollen layer, there was a "buffer layer" that could sorb more toluene molecules than the bulk-like layer. This buffer layer was found not only in the adsorbed sample but also in the standard spin-cast PMMA thin films on the substrate. When the polymer chains were firmly adsorbed and immobilized on the Si substrate, the freedom of the possible structure right next to the tightly bound layer was reduced, which restricted the relaxation of the conformation of the polymer chain strongly. The "buffer layer" was manifested by the sorption of toluene with different scattering length density contrasts.
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Affiliation(s)
- Keisuke Shimokita
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan.
| | - Katsuhiro Yamamoto
- Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan.
| | - Noboru Miyata
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki, 319-1106, Japan.
| | - Yohei Nakanishi
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Motoki Shibata
- Office of Society-Academia Collaboration for Innovation, Kyoto University, Kyoto, 606-8501, Japan
| | - Mikihito Takenaka
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Norifumi L Yamada
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tokai, Ibaraki, 319-1106, Japan
| | - Hideki Seto
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tokai, Ibaraki, 319-1106, Japan
| | - Hiroyuki Aoki
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tokai, Ibaraki, 319-1106, Japan
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan
| | - Tsukasa Miyazaki
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki, 319-1106, Japan.
- Office of Society-Academia Collaboration for Innovation, Kyoto University, Kyoto, 606-8501, Japan
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Qin H, Liu K, Tian M, Mi J, Zhang L. How interfacial strength affects dielectric performance in Silica/Poly(methyl acrylate) nanocomposites? POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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7
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Infrared Linear Dichroism for the Analysis of Molecular Orientation in Polymers and in Polymer Composites. Polymers (Basel) 2022; 14:polym14061257. [PMID: 35335588 PMCID: PMC8954227 DOI: 10.3390/polym14061257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/14/2022] [Accepted: 03/17/2022] [Indexed: 02/07/2023] Open
Abstract
The mechanical properties of polymeric materials are strongly affected by molecular orientation occurring under processing conditions. Infrared dichroism is particularly well suited for characterizing polymer chain orientation at a molecular level. The usefulness of this technique has been demonstrated through various applications in homopolymers, semi-crystalline polymers, copolymers, polymer blends, as well as in polymer composites. Determination of molecular orientation can be carried out in the mid- and near-infrared ranges and very small dichroic effects can be detected with the use of a photoelastic modulator. Chain orientation in polymer composites is seen to increase with the filler content in the case of a strong interface between the two phases, making possible a quantification of the degree of bonding between the host polymeric matrix and the incorporated inclusions.
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Zhou Y, Schweizer KS. Theory for the Elementary Time Scale of Stress Relaxation in Polymer Nanocomposites. ACS Macro Lett 2022; 11:199-204. [PMID: 35574769 DOI: 10.1021/acsmacrolett.1c00732] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We construct a microscopic theory for the elementary time scale of stress relaxation in dense polymer nanocomposites. The key dynamical event is proposed to involve the rearrangement of cohesive segment-nanoparticle (NP) tight bridging complexes via an activated small NP dilational motion, which allows the confined segments to relax. The corresponding activation energy is determined by the NP bridge coordination number and potential of mean force barrier. The activation energy varies nonlinearly with interfacial cohesion strength and NP concentration, and a universal master curve is predicted. The theory is in very good agreement with experiments. The underlying ideas are relevant to a variety of other hybrid macromolecular materials involving hard particles and soft macromolecules.
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Shimokita K, Yamamoto K, Miyata N, Nakanishi Y, Ogawa H, Takenaka M, Yamada NL, Miyazaki T. Investigation of Interfacial Water Accumulation between Polypropylene Thin Film and Si Substrate by Neutron Reflectivity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:14550-14557. [PMID: 34865493 DOI: 10.1021/acs.langmuir.1c02771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We performed neutron reflectivity (NR) measurements of isotactic polypropylene (PP) thin films deposited on a Si substrate at the saturated vapor pressure of deuterated water to investigate interfacial water accumulation between the PP and metal surfaces in PP-based polymer/inorganic filler nanocomposites and metal/resin bonding materials. The PP thin films prepared on a Si substrate by a spin-coating technique were adequate as a model system for the PP/metal interface in these materials. A water-rich layer with a maximum water concentration of 0.5, which was considerably higher than those reported in previous studies of organic/inorganic interfaces, was observed within a width of approximately 3 nm at the interface under saturated vapor conditions. This could be attributed to the weak interaction between the PP thin film and the Si substrate. The pathway of moisture transport to the interfacial region was along the interface rather than through the PP film because the hydrophobic PP thin film does not entirely swell with water vapor.
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Affiliation(s)
- Keisuke Shimokita
- Functional Base Products Sector, Nitto Denko Corporation, 18 Hirayama, Nakahara, Toyohashi, Aichi 441-3194, Japan
- Department of Life Science and Applied Chemistry, Gradual School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Katsuhiro Yamamoto
- Department of Life Science and Applied Chemistry, Gradual School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Noboru Miyata
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Yohei Nakanishi
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Hiroki Ogawa
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Mikihito Takenaka
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
| | - Norifumi L Yamada
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Tsukasa Miyazaki
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
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Izumi A, Shudo Y, Shibayama M, Miyata N, Miyazaki T, Aoki H. In Situ Neutron Reflectometry Analysis of Interfacial Structure Formation between Phenolic Resin and Silica during Curing. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:13867-13872. [PMID: 34783569 DOI: 10.1021/acs.langmuir.1c02313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The structural formation mechanism of phenolic resin-silica interfaces was investigated in situ by neutron reflectometry during curing. There was a 4 nm thick novolac resin adsorption layer on the silica surface before curing. The curing reaction of the novolac resin with hexamethylenetetramine (HMTA) increased the coherent neutron scattering length density of the resin due to the cure shrinkage accompanied by the volatilization of ammonia, which is a byproduct of HMTA decomposition. As curing proceeded at 180 °C, the thickness of the bulk layer increased despite the cure shrinkage, and the thickness of the interfacial layer decreased from 4 to 1 nm. This is attributed to the diffusion of decomposed HMTA fragments generated in the bulk layer into the interfacial novolac adsorption layer during diffusion throughout the bulk layer, incorporating the upper part of the interfacial layer reacting with the fragment into the bulk layer. On the other hand, the fragments could not diffuse into the tightly bound immobile segments of novolac resin in direct contact with the silica surface, retaining the 1-2 nm thick interfacial layer in the cured resin. This structural formation mechanism caused interfacial cross-link inhomogeneity in the cured resin on the silica surface.
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Affiliation(s)
- Atsushi Izumi
- Corporate Engineering Center, Sumitomo Bakelite Co., Ltd., 2100 Takayanagi, Fujieda, Shizuoka 426-0041, Japan
| | - Yasuyuki Shudo
- Corporate Engineering Center, Sumitomo Bakelite Co., Ltd., 2100 Takayanagi, Fujieda, Shizuoka 426-0041, Japan
| | - Mitsuhiro Shibayama
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan
| | - Noboru Miyata
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan
| | - Tsukasa Miyazaki
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan
| | - Hiroyuki Aoki
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Naka, Ibaraki 319-1195, Japan
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 203-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan
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Miyazaki T, Miyata N, Arima-Osonoi H, Kira H, Ohuchi K, Kasai S, Tsumura Y, Aoki H. Layered Structure in the Crystalline Adsorption Layer and the Leaching Process of Poly(vinyl alcohol) Revealed by Neutron Reflectivity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:9873-9882. [PMID: 34348461 DOI: 10.1021/acs.langmuir.1c01563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We investigated the structure of the crystalline adsorption layer of poly(vinyl alcohol) (PVA) in hot water by neutron reflectivity in two cases: when the adsorption layer is exposed on the substrate by leaching the upper bulk layer and when it is deeply embedded between a relatively thick PVA film and substrate. In both cases, the PVA adsorption layer consists of three layers on the Si substrate. The bottom layer, consisting of amorphous chains that are strongly constrained on the substrate, is not swollen even in hot water at 90 °C. The middle layer, consisting of amorphous chains that are much more mobile compared with those in the bottom layer, has no freedom to assume a crystalline form. Only the molecular chains in the top layer are crystallizable in the adsorption layer, leading to a heterogeneous layered structure in the film thickness direction. This layered structure is attributed to the crystallizable chains of PVA during the formation of the adsorption layer driven by hydrogen bonding. However, the structure and dynamics in the adsorption layer may differ in both cases because the molecular chains in the vicinity of the surface seem to be affected by surface effects even in the adsorption layer.
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Affiliation(s)
- Tsukasa Miyazaki
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Noboru Miyata
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Hiroshi Arima-Osonoi
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Hiroshi Kira
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Keiichi Ohuchi
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Satoshi Kasai
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Yoshihiro Tsumura
- Kurashiki Research Center, Kuraray Co., Ltd., 2045-1, Sakazu, Kurashiki, Okayama 710-0801, Japan
| | - Hiroyuki Aoki
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
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12
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Sattar MA. Interface Structure and Dynamics in Polymer‐Nanoparticle Hybrids: A Review on Molecular Mechanisms Underlying the Improved Interfaces. ChemistrySelect 2021. [DOI: 10.1002/slct.202100831] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Mohammad Abdul Sattar
- R&D Centre MRF Limited Chennai 600019 India
- Colloid and Interface Chemistry Laboratory Department of Chemistry Indian Institute of Technology Madras Chennai 600036 India
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Miyazaki T, Shimokita K, Yamamoto K, Aoki H, Yamada NL, Miyata N. Neutron Reflectivity on the Mobile Surface and Immobile Interfacial Layers in the Poly(vinyl acetate) Adsorption Layer on a Si Substrate with Deuterated Toluene Vapor-Induced Swelling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:15181-15188. [PMID: 33259712 DOI: 10.1021/acs.langmuir.0c03025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We investigated the polymer chain dynamics in a 2-3 nm thick poly(vinyl acetate) (PVAc) adsorption layer on a Si substrate with a native oxide layer via neutron reflectometry combined with toluene vapor-induced swelling. We can investigate the polymer chain dynamics difference in the film thickness direction by the difference in the degree of swelling of the polymer layers detected by neutron reflectometry. The mobility of the polymer chains depends on the distance from the substrate. The results elucidated that the interfacial layer with a thickness of approximately 1 nm did not swell at all with toluene vapor, which is a solvent for PVAc. Meanwhile, the surface layer excessively swells with toluene vapor compared to the bulk. This indicates that the polymer chain within the interfacial region is immobilized by the substrate through hydrogen-bonding interaction, but in the surface region, the surface effect overcomes this interfacial interaction. We concluded that the polymer chains in the adsorption layer are either strongly constrained to the substrate, owing to hydrogen bonding, or more mobile than the bulk, owing to the surface effect.
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Affiliation(s)
- Tsukasa Miyazaki
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan
| | - Keisuke Shimokita
- Functional Base Products Sector, Nitto Denko Corporation, 18 Hirayama, Nakahara, Toyohashi, Aichi 441-3194, Japan
- Department of Life Science and Applied Chemistry, Gradual School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Katsuhiro Yamamoto
- Department of Life Science and Applied Chemistry, Gradual School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Hiroyuki Aoki
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Norifumi L Yamada
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 203-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Noboru Miyata
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan
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14
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Walker CC, Genzer J, Santiso EE. Effect of Poly(vinyl butyral) Comonomer Sequence on Adhesion to Amorphous Silica: A Coarse-Grained Molecular Dynamics Study. ACS APPLIED MATERIALS & INTERFACES 2020; 12:47879-47890. [PMID: 32921047 DOI: 10.1021/acsami.0c10747] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Modulating a comonomer sequence, in addition to the overall chemical composition, is the key to unlocking the true potential of many existing commercial copolymers. We employ coarse-grained molecular dynamics (MD) simulations to study the behavior of random-blocky poly(vinyl butyral-co-vinyl alcohol) (PVB) melts in contact with an amorphous silica surface, representing the interface found in laminated safety glass. Our two-pronged coarse-graining approach utilizes both macroscopic thermophysical data and all-atom MD simulation data. Polymer-polymer nonbonded interactions are described by the fused-sphere SAFT-γ Mie equation of state, while bonded interactions are derived using Boltzmann inversion to match the bond and angle distributions from all-atom PVB chains. Spatially dependent polymer-surface interactions are mapped from a hydroxylated all-atom amorphous silica slab model and all-atom monomers to an external potential acting on the coarse-grained sites. We discovered an unexpected complex relationship between the blockiness parameter and the adhesion energy. The adhesion strength between PVB copolymers with intermediate VA content and silica was found to be maximal for random-blocky copolymers with a moderately high degree of blockiness rather than for diblock copolymers. We attribute this to two main factors: (1) changes in morphology, which dramatically alter the number of VA beads interacting with the surface and (2) a non-negligible contribution of vinyl butyral (VB) monomers to adhesion energy because of their preference to adsorb to zones with low hydroxyl density on the silica surface.
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Affiliation(s)
- Christopher C Walker
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jan Genzer
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Erik E Santiso
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
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15
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Xu J, Lv C, Du B, Wang X, Tsui OKC. Effective Viscosity of Unentangled Random Copolymer Films of Styrene and 4-Methoxystyrene with Different Copolymer Compositions. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01394] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jianquan Xu
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong, China
| | - Chao Lv
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science & Engineering, Zhejiang University, Hangzhou 310027, China
| | - Binyang Du
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science & Engineering, Zhejiang University, Hangzhou 310027, China
| | - Xinping Wang
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Ophelia K. C. Tsui
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon 999077, Hong Kong, China
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16
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Blivi AS, Bedoui F, Weigand S, Kondo D. Multiscale analysis of nanoparticles size effects on thermal, elastic, and viscoelastic properties of nano‐reinforced polymers. POLYM ENG SCI 2020. [DOI: 10.1002/pen.25413] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Adoté S. Blivi
- Laboratoire Roberval, UMR‐CNRS 7037Sorbonne Universités, Université de Technologie de Compiègne Compiègne France
| | - Fahmi Bedoui
- Laboratoire Roberval, UMR‐CNRS 7037Sorbonne Universités, Université de Technologie de Compiègne Compiègne France
| | - Steven Weigand
- Member of the DND‐CAT Synchrotron Research Center, ANLNorthwestern University Argonne Illinois USA
| | - Djimédo Kondo
- IJLRDA, UMR‐CNRS 7190Sorbonne Universités, Université Pierre et Marie Curie Paris France
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17
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Zboncak M, Ondreas F, Uhlir V, Lepcio P, Michalicka J, Jancar J. Translation of segment scale stiffening into macroscale reinforcement in polymer nanocomposites. POLYM ENG SCI 2019. [DOI: 10.1002/pen.25317] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marek Zboncak
- CEITEC, Brno University of Technology Brno 61200 Czech Republic
| | | | - Vojtech Uhlir
- CEITEC, Brno University of Technology Brno 61200 Czech Republic
| | - Petr Lepcio
- CEITEC, Brno University of Technology Brno 61200 Czech Republic
| | - Jan Michalicka
- CEITEC, Brno University of Technology Brno 61200 Czech Republic
| | - Josef Jancar
- CEITEC, Brno University of Technology Brno 61200 Czech Republic
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18
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Wang T, Yan J, Yuan H, Xu J, Lam HY, Yu X, Lv C, Du B, Tsui OKC. Tg Confinement Effect of Random Copolymers of 4- tert-Butylstyrene and 4-Acetoxystyrene with Different Compositions. ACS Macro Lett 2019; 8:1280-1284. [PMID: 35651168 DOI: 10.1021/acsmacrolett.9b00568] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We observe that the Tg confinement effect of polymer films can saturate with polymer-substrate interaction. Thickness dependences of the glass transition temperature, Tg(h0), of random copolymer films of 4-tert-butylstyrene (TBS) and 4-acetoxystyrene (AS) supported by silica (SiOx) were measured for different TBS concentrations, XTBS. For 0 ≤ XTBS ≤ 0.47, Tg(h0) displays identical enhancements, independent of XTBS. For XTBS > ∼0.66; however, Tg(h0) decreases steadily with XTBS. The XTBS > 0.66 result is in keeping with expectations that TBS interacts less strongly with SiOx than AS does, and weaker polymer-substrate interaction renders greater dominance of the air surface over substrate surface on Tg, and thereby Tg reduction. We propose that saturation in Tg(h0) found for XTBS ≤ 0.47 is caused by the maximization in polymer-substrate-specific bond formation. Further experiments and a calculation support this proposition.
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Affiliation(s)
- Tong Wang
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
| | - Jinsong Yan
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
| | - Hailin Yuan
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
| | - Jianquan Xu
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
| | - Ho Yi Lam
- Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
| | - Xuanji Yu
- Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, United States
| | - Chao Lv
- Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Binyang Du
- Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Ophelia K. C. Tsui
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
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19
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Khatiwada BK, Blum FD. Tightly Bound PMMA on Silica Has Reduced Heat Capacities. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:11482-11490. [PMID: 31408349 DOI: 10.1021/acs.langmuir.9b01847] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The heat capacities of very small adsorbed amounts of poly(methyl methacrylate) on high-surface-area silica (Cab-O-Sil) were measured using temperature-modulated differential scanning calorimetry (TMDSC) using a quasi-isothermal method and interpreted via different models. The composition-dependent heat capacities of the adsorbed samples were measurably less than those predicted with a simple mixture model. A two-state model, composed of tightly and loosely bound polymer, fits the data better with heat capacities of the tightly bound polymer found to be 70-80% (glassy region) and 70-94% (rubbery region) of that of the bulk polymer at the same temperatures. The amount of tightly bound polymer was estimated to be about 1.2 mg/m2 (about 1 nm thickness) in both the glassy and rubbery regions, consistent with heat flow measurements. The data sets were also extensive enough to model them with a more detailed layered gradient model, including a nonzero heat capacity for the polymer at zero adsorbed amount, which increased based on an exponential growth function to bulk polymer value of the heat capacity away from the surface. More importantly, this gradient model mimicked the experimental dependence on adsorbed amounts in the tightly bound adsorbed amount region (approximately 1 mg/m2). This model provided, for the first time, an experimental estimate of the heat capacity of the polymer adsorbed closest to the surface. The fractional heat capacity of the adsorbed polymer closest to the silica surface, relative to bulk polymer, increased with temperature from 0.3 (well below) to 0.8 (well above the bulk Tg). It was also possible to estimate the exponential growth parameter of the development from the initial heat capacities to the bulk heat capacity as 0.4 to 0.6 mg/m2, identifying a distance scale (0.3 to 0.5 nm) consistent with the notion of a transition from tightly bound to loosely bound polymer.
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Affiliation(s)
- Bal K Khatiwada
- Department of Chemistry , Oklahoma State University , Stillwater , Oklahoma 74078 , United States
| | - Frank D Blum
- Department of Chemistry , Oklahoma State University , Stillwater , Oklahoma 74078 , United States
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20
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McClements J, Shaver MP, Sefiane K, Koutsos V. Morphology of Poly(styrene- co-butadiene) Random Copolymer Thin Films and Nanostructures on a Graphite Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:7784-7796. [PMID: 29757657 DOI: 10.1021/acs.langmuir.8b01020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We studied the morphology of poly(styrene- co-butadiene) random copolymers on a graphite surface. Polymer solutions were spin coated onto graphite, at various concentrations and molecular weights. The polymer films and nanostructures were imaged using atomic force microscopy. Above the overlap concentration, thin films formed. However, total wetting did not occur, despite the polymers being well above their Tg. Instead, dewetting was observed, suggesting the films were in a state of metastable equilibrium. At lower concentrations, the polymers formed networks, nanoislands, and nanoribbons. Ordered nanopatterns were observed on the surface; the polymers orientated themselves due to π-π stacking interactions reflecting the crystalline structure of the graphite. At the lowest concentration, this ordering was very pronounced. At higher concentrations, it was less defined but still statistically significant. Higher degrees of ordering were observed with poly(styrene- co-butadiene) than polystyrene and polybutadiene homopolymers as the copolymer's aromatic rings are distributed along a flexible chain, which maximizes π-π stacking. At the two lowest concentrations, the size of the nanoislands and nanoribbons remained similar with varying molecular weight. However, at higher concentrations, the polymer network features were largest at the lowest molecular weight, indicating that in this case, a large proportion of shorter chains stay on top of the adsorbed ones. The contact angles of the polymer nanostructures remained mostly constant with size, which is due to the strong polymer/graphite adhesion dominating over line tension and entropic effects.
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Affiliation(s)
- Jake McClements
- School of Engineering, Institute for Materials and Processes , The University of Edinburgh , Sanderson Building, King's Buildings , Edinburgh EH9 3FB , U.K
| | - Michael P Shaver
- EaStCHEM School of Chemistry , University of Edinburgh , Joseph Black Building, King's Buildings, David Brewster Road , Edinburgh EH9 3FJ , U.K
| | - Khellil Sefiane
- School of Engineering, Institute for Materials and Processes , The University of Edinburgh , Sanderson Building, King's Buildings , Edinburgh EH9 3FB , U.K
| | - Vasileios Koutsos
- School of Engineering, Institute for Materials and Processes , The University of Edinburgh , Sanderson Building, King's Buildings , Edinburgh EH9 3FB , U.K
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21
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Negash S, Tatek YB, Tsige M. Effect of tacticity on the structure and glass transition temperature of polystyrene adsorbed onto solid surfaces. J Chem Phys 2018; 148:134705. [DOI: 10.1063/1.5010276] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Solomon Negash
- Department of Physics, Addis Ababa University, Addis Ababa, Ethiopia
| | - Yergou B. Tatek
- Department of Physics, Addis Ababa University, Addis Ababa, Ethiopia
| | - Mesfin Tsige
- Department of Polymer Science, The University of Akron, Akron, Ohio 44325, USA
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22
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Structure, electronic, optical and thermodynamic behavior on the polymerization of PMMA: A DFT investigation. Comput Biol Chem 2017; 72:192-198. [PMID: 29276009 DOI: 10.1016/j.compbiolchem.2017.10.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 09/23/2017] [Accepted: 10/31/2017] [Indexed: 10/18/2022]
Abstract
A density functional theory based scrutiny is implemented on the structure, electronic, optical and thermodynamic properties of the Poly (Methyl MethAcrylate) polymers (PMMA or nMMA; n = 1-5). The quantum chemical descriptors, e.g. HOMO-LUMO gap, ionization potential, chemical hardness, binding energies etc. of the PMMA polymers provides the measure for the structural and electronic properties. The parameters polarizability (α) and hyperpolarizability (β) provides information for the non-linear optical (NLO) properties of the polymers. The absorption range of the PMMA polymer in the electromagnetic radiation spectrum during its growth is assessed by the UltraViolet-Visible (UV-vis) optical absorption spectra. To gain further insight on the origin of stability during the polymerization process, we have simulated frontier molecular orbitals (FMOs) and various thermodynamic properties, viz., entropy (S), enthalpy (H) and Gibbs free energy (G).
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23
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McClements J, Buffone C, Shaver MP, Sefiane K, Koutsos V. Poly(styrene-co-butadiene) random copolymer thin films and nanostructures on a mica surface: morphology and contact angles of nanodroplets. SOFT MATTER 2017; 13:6152-6166. [PMID: 28795749 DOI: 10.1039/c7sm00994a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The self-assembly of poly(styrene-co-butadiene) random copolymers on mica surfaces was studied by varying solution concentrations and polymer molecular weights. Toluene solutions of the poly(styrene-co-butadiene) samples were spin coated onto a mica surface and the resulting polymer morphology was investigated by atomic force microscopy. At higher concentrations, thin films formed with varying thicknesses; some dewetting was observed which depended on the molecular weight. Total dewetting did not occur despite the polymer's low glass transition temperature. Instead, partial dewetting was observed suggesting that the polymer was in a metastable equilibrium state. At lower concentrations, spherical cap shaped nanodroplets formed with varying sizes from single polymer chains to aggregates containing millions of chains. As the molecular weight was increased, fewer aggregates were observed on the surface, albeit with larger sizes resulting from increased solution viscosities and more chain entanglements at higher molecular weights. The contact angles of the nanodroplets were shown to be size dependent. A minimum contact angle occurs for droplets with radii of 100-250 nm at each molecular weight. Droplets smaller than 100 nm showed a sharp increase in contact angle; attributed to an increase in the elastic modulus of the droplets, in addition, to a positive line tension value. Droplets larger than 250 nm also showed an increased contact angle due to surface heterogeneities which cannot be avoided for larger droplets. This increase in contact angle plateaus as the droplet size reaches the macroscopic scale.
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Affiliation(s)
- Jake McClements
- Institute for Materials and Processes, School of Engineering, The University of Edinburgh, Sanderson Building, King's Buildings, Edinburgh EH9 3FB, UK.
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24
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Sato K, Kobayashi S, Sekishita A, Wakui M, Tanaka M. Synthesis and Thrombogenicity Evaluation of Poly(3-methoxypropionic acid vinyl ester): A Candidate for Blood-Compatible Polymers. Biomacromolecules 2017; 18:1609-1616. [DOI: 10.1021/acs.biomac.7b00221] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Kazuhiro Sato
- Department
of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
| | - Shingo Kobayashi
- Institute
for Materials Chemistry and Engineering, Kyushu University, CE41
744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Asuka Sekishita
- Department
of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
| | - Miyuki Wakui
- Department
of Biochemical Engineering, Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
| | - Masaru Tanaka
- Institute
for Materials Chemistry and Engineering, Kyushu University, CE41
744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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25
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Hetayothin B, Cabaniss RA, Blum FD. Does Plasticizer Penetrate Tightly Bound Polymer in Adsorbed Poly(vinyl acetate) on Silica? Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Boonta Hetayothin
- Department of Chemistry and Biochemistry, California State University, Los
Angeles, California 90032, United States
| | | | - Frank D. Blum
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, United States
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26
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Janes DW, Bilchak C, Durning CJ. Decoupling energetic modifications to diffusion from free volume in polymer/nanoparticle composites. SOFT MATTER 2017; 13:677-685. [PMID: 28009881 DOI: 10.1039/c6sm02172g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Diffusion coefficients of small molecules in a model composite of spherical nanoparticles and polymer with attractive interfacial interactions are reduced from that in the pure polymer, to a degree far below the level expected from geometric tortuosity arguments. We determine whether such dramatic reductions are due to modifications to the matrix polymer free volume near the nanoparticle surface, or alternatively are due to energetic attractions between the diffusants and nanoparticle surface. We performed ethyl acetate sorption experiments within the vicinity of the polymer glass transition (Tg ≤ T ≤ Tg + 25 K) for a model polymer/nanoparticle composite, silica-filled poly(methyl acrylate). By application of the Vrentas-Duda free volume theory of diffusion we have decoupled the energetic effects from those related to free-volume and segmental dynamics. While the latter is unaffected by addition of nanoparticles, the energy needed for the ethyl acetate diffusant to overcome neighboring attractive forces doubles after adding 40 vol% nanoparticles with a diameter of 14 nm. This is qualitatively consistent with hydrogen bonding interactions between the silica surface and ethyl acetate slowing its rate of diffusion. On the other hand for benzene, which does not hydrogen bond to the silica surface, diffusion coefficients that can be explained by tortuosity effects were obtained. This work provides quantitative evidence that the diffusant-filler energetic interactions and geometric blocking effects can be fully responsible for the substantially reduced diffusivity commonly observed in polymer/nanoparticle composite systems.
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Affiliation(s)
| | - Connor Bilchak
- Department of Chemical Engineering, Columbia University, New York, NY 10027, USA.
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