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Temperini ME, Polito R, Venanzi T, Baldassarre L, Hu H, Ciracì C, Pea M, Notargiacomo A, Mattioli F, Ortolani M, Giliberti V. An Infrared Nanospectroscopy Technique for the Study of Electric-Field-Induced Molecular Dynamics. NANO LETTERS 2024; 24:9808-9815. [PMID: 39089683 PMCID: PMC11328210 DOI: 10.1021/acs.nanolett.4c01387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Static electric fields play a considerable role in a variety of molecular nanosystems as diverse as single-molecule junctions, molecules supporting electrostatic catalysis, and biological cell membranes incorporating proteins. External electric fields can be applied to nanoscale samples with a conductive atomic force microscopy (AFM) probe in contact mode, but typically, no structural information is retrieved. Here we combine photothermal expansion infrared (IR) nanospectroscopy with electrostatic AFM probes to measure nanometric volumes where the IR field enhancement and the static electric field overlap spatially. We leverage the vibrational Stark effect in the polymer poly(methyl methacrylate) for calibrating the local electric field strength. In the relevant case of membrane protein bacteriorhodopsin, we observe electric-field-induced changes of the protein backbone conformation and residue protonation state. The proposed technique also has the potential to measure DC currents and IR spectra simultaneously, insofar enabling the monitoring of the possible interplay between charge transport and other effects.
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Affiliation(s)
- Maria Eleonora Temperini
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- Center for Life Nano- & Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Roma, Italy
| | - Raffaella Polito
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Tommaso Venanzi
- Center for Life Nano- & Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Roma, Italy
| | - Leonetta Baldassarre
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Huatian Hu
- Center for Biomolecular Nanotechnologies, Istituto Italiano di Tecnologia, Via Barsanti 14, I-73010 Arnesano, Italy
| | - Cristian Ciracì
- Center for Biomolecular Nanotechnologies, Istituto Italiano di Tecnologia, Via Barsanti 14, I-73010 Arnesano, Italy
| | - Marialilia Pea
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy
| | - Andrea Notargiacomo
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy
| | - Francesco Mattioli
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy
| | - Michele Ortolani
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- Center for Life Nano- & Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Roma, Italy
| | - Valeria Giliberti
- Center for Life Nano- & Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Roma, Italy
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2
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Chat K, Tu W, Beena Unni A, Adrjanowicz K. Influence of Tacticity on the Glass-Transition Dynamics of Poly(methyl methacrylate) (PMMA) under Elevated Pressure and Geometrical Nanoconfinement. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01341] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Katarzyna Chat
- Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
- Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pulku Piechoty 1a, 41-500 Chorzow, Poland
| | - Wenkang Tu
- Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
- Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pulku Piechoty 1a, 41-500 Chorzow, Poland
| | - Aparna Beena Unni
- Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
- Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pulku Piechoty 1a, 41-500 Chorzow, Poland
| | - Karolina Adrjanowicz
- Institute of Physics, University of Silesia, 75 Pulku Piechoty 1, 41-500 Chorzow, Poland
- Silesian Center for Education and Interdisciplinary Research (SMCEBI), 75 Pulku Piechoty 1a, 41-500 Chorzow, Poland
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Gennaro A, Rosa AS, Cornelis P, Pfeiffer H, Disalvo EA, Wagner P, Wübbenhorst M. A compact device for simultaneous dielectric spectroscopy and microgravimetric analysis under controlled humidity. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:125106. [PMID: 31893814 DOI: 10.1063/1.5125301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 11/15/2019] [Indexed: 06/10/2023]
Abstract
Water plays a key role in the functioning of natural and synthetic molecular systems. Despite several hydration studies, different techniques are employed individually for monitoring different physical features such as kinetics, dynamics, and absorption. This study describes a compact hydration cell that enables simultaneous dielectric relaxation spectroscopy (DRS) and mass loss/uptake measurements in thin organic layers under controlled humidity conditions and in a wide temperature range. This approach enabled us to correlate the physical quantities obtained during the same experiment by complementary techniques. To demonstrate the performance of this device, a 200 nm thick poly(methyl methacrylate) (PMMA) layer was measured at various relative humidity levels (0%-75%), temperatures (25-75 °C), and frequencies (DRS: 0.1 Hz-1 MHz) to study how hydration and dehydration processes affect its molecular dynamics. The results show the capability of this setup to study the changes in the PMMA film regarding the kinetics and molecular dynamics upon variation of the water content.
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Affiliation(s)
- Alessia Gennaro
- KU Leuven, Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics (ZMB), Celestijnenlaan 200 D, 3001 Leuven, Belgium
| | - Antonio S Rosa
- Applied Biophysics and Food Research Center (Centro de Investigaciones en Biofísica Aplicada y Alimentos, CIBAAL), National University of Santiago del Estero and National Scientific and Technical Research Council CONICET, RN 9 - Km 1125, 4206 Santiago del Estero, Argentina
| | - Peter Cornelis
- KU Leuven, Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics (ZMB), Celestijnenlaan 200 D, 3001 Leuven, Belgium
| | - Helge Pfeiffer
- KU Leuven, Department of Materials Engineering (MTM), Kasteelpark Arenberg 44, 3001 Leuven, Belgium
| | - Edgardo A Disalvo
- Applied Biophysics and Food Research Center (Centro de Investigaciones en Biofísica Aplicada y Alimentos, CIBAAL), National University of Santiago del Estero and National Scientific and Technical Research Council CONICET, RN 9 - Km 1125, 4206 Santiago del Estero, Argentina
| | - Patrick Wagner
- KU Leuven, Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics (ZMB), Celestijnenlaan 200 D, 3001 Leuven, Belgium
| | - Michael Wübbenhorst
- KU Leuven, Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics (ZMB), Celestijnenlaan 200 D, 3001 Leuven, Belgium
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4
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Baglay RR, Roth CB. Local glass transition temperatureTg(z) of polystyrene next to different polymers: Hard vs. soft confinement. J Chem Phys 2017; 146:203307. [DOI: 10.1063/1.4975168] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Roman R. Baglay
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA
| | - Connie B. Roth
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA
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5
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Kolluru PV, Chasiotis I. A master curve for the size and strain rate dependent large deformation behavior of PS nanofibers at room temperature. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.07.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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6
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Vibrational nano-spectroscopic imaging correlating structure with intermolecular coupling and dynamics. Nat Commun 2014; 5:3587. [PMID: 24721995 PMCID: PMC4071972 DOI: 10.1038/ncomms4587] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 03/06/2014] [Indexed: 11/20/2022] Open
Abstract
Molecular self-assembly, the function of biomembranes and the performance of organic solar cells rely on nanoscale molecular interactions. Understanding and control of such materials have been impeded by difficulties in imaging their properties with the desired nanometre spatial resolution, attomolar sensitivity and intermolecular spectroscopic specificity. Here we implement vibrational scattering-scanning near-field optical microscopy with high spectral precision to investigate the structure–function relationship in nano-phase separated block copolymers. A vibrational resonance is used as a sensitive reporter of the local chemical environment and we image, with few nanometre spatial resolution and 0.2 cm−1 spectral precision, solvatochromic Stark shifts and line broadening correlated with molecular-scale morphologies. We discriminate local variations in electric fields between nano-domains with quantitative agreement with dielectric continuum models. This ability to directly resolve nanoscale morphology and associated intermolecular interactions can form a basis for the systematic control of functionality in multicomponent soft matter systems. Quantifying intermolecular coupling and local morphology is important to understand soft matter systems. Pollard et al. show how multispectral vibrational near-field optical microscopy can be used to image molecular-scale morphology and intermolecular interactions with nanometre spatial resolution.
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Nguyen HK, Labardi M, Capaccioli S, Lucchesi M, Rolla P, Prevosto D. Interfacial and Annealing Effects on Primary α-Relaxation of Ultrathin Polymer Films Investigated at Nanoscale. Macromolecules 2012. [DOI: 10.1021/ma202757q] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hung K. Nguyen
- Dipartimento
di Fisica “Enrico Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Massimiliano Labardi
- CNR-IPCF, Consiglio Nazionale delle
Ricerche, Istituto per i Processi Chimico-Fisici, c/o Dip. Fisica Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Simone Capaccioli
- Dipartimento
di Fisica “Enrico Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
- CNR-IPCF, Consiglio Nazionale delle
Ricerche, Istituto per i Processi Chimico-Fisici, c/o Dip. Fisica Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Mauro Lucchesi
- Dipartimento
di Fisica “Enrico Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
- CNR-IPCF, Consiglio Nazionale delle
Ricerche, Istituto per i Processi Chimico-Fisici, c/o Dip. Fisica Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Pierangelo Rolla
- Dipartimento
di Fisica “Enrico Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
- CNR-IPCF, Consiglio Nazionale delle
Ricerche, Istituto per i Processi Chimico-Fisici, c/o Dip. Fisica Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Daniele Prevosto
- CNR-IPCF, Consiglio Nazionale delle
Ricerche, Istituto per i Processi Chimico-Fisici, c/o Dip. Fisica Largo Pontecorvo 3, 56127 Pisa, Italy
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8
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Nguyen HK, Prevosto D, Labardi M, Capaccioli S, Lucchesi M, Rolla P. Effect of Confinement on Structural Relaxation in Ultrathin Polymer Films Investigated by Local Dielectric Spectroscopy. Macromolecules 2011. [DOI: 10.1021/ma200440z] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Hung K. Nguyen
- Dipartimento di Fisica “Enrico Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Daniele Prevosto
- Consiglio Nazionale delle Ricerche, Istituto per i Processi Chimico-Fisici, CNR-IPCF, c/o Dip. Fisica Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Massimiliano Labardi
- Consiglio Nazionale delle Ricerche, Istituto per i Processi Chimico-Fisici, CNR-IPCF, c/o Dip. Fisica Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Simone Capaccioli
- Dipartimento di Fisica “Enrico Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
- Consiglio Nazionale delle Ricerche, Istituto per i Processi Chimico-Fisici, CNR-IPCF, c/o Dip. Fisica Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Mauro Lucchesi
- Dipartimento di Fisica “Enrico Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
- Consiglio Nazionale delle Ricerche, Istituto per i Processi Chimico-Fisici, CNR-IPCF, c/o Dip. Fisica Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Pierangelo Rolla
- Dipartimento di Fisica “Enrico Fermi”, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
- Consiglio Nazionale delle Ricerche, Istituto per i Processi Chimico-Fisici, CNR-IPCF, c/o Dip. Fisica Largo Pontecorvo 3, 56127 Pisa, Italy
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Serghei A, Tress M, Kremer F. The glass transition of thin polymer films in relation to the interfacial dynamics. J Chem Phys 2010; 131:154904. [PMID: 20568881 DOI: 10.1063/1.3248368] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
As opposed to measurements on the glass transition of a polymer in the bulk, measurements of thin polymer layers reflect--due to the alterations of the glassy dynamics at the confining interfaces--several contributions acting together to give the net response of a polymer film. This fundamental difference is exemplified in detail for the particular case of broadband dielectric spectroscopy, an experimental tool extensively employed to investigate the glassy dynamics of polymers under condition of geometrical confinement.
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Affiliation(s)
- A Serghei
- Institute for Experimental Physics I, University of Leipzig, 04103 Leipzig, Germany.
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10
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Kim S, Hewlett SA, Roth CB, Torkelson JM. Confinement effects on glass transition temperature, transition breadth, and expansivity: comparison of ellipsometry and fluorescence measurements on polystyrene films. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2009; 30:83-92. [PMID: 19784679 DOI: 10.1140/epje/i2009-10510-y] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2009] [Revised: 08/03/2009] [Accepted: 08/21/2009] [Indexed: 05/28/2023]
Abstract
Using ellipsometry, we characterized the nanoconfinement effect on the glass transition temperature (T (g)of supported polystyrene (PS) films employing two methods: the intersection of fits to the temperature (Tdependences of rubbery- and glassy-state thicknesses, and the transition mid-point between rubbery- and glassy-state expansivities. The results demonstrate a strong effect of thickness: T(g) (bulk) - T(g)(23 nm) = 10 degrees C. The T -range needed for accurate measurement increases significantly with decreasing thickness, an effect that arises from the broadening of the transition with confinement and a region below T (g) where expansivity slowly decreases with decreasing T . As determined from expansivities, the T (g) breadth triples in going from bulk films to a 21-nm-thick film; this broadening of the transition may be a more dramatic effect of confinement than the T (g) reduction itself. In contrast, there is little effect of confinement on the rubbery- and glassy-state expansivities. Compared with ellipsometry, T (g) 's from fluorescence agree well in bulk films but yield lower values in nanoconfined films: T (g)(bulk) - T (g)(23 nm) = 15( degrees ) C via fluorescence. This small difference in the T (g) confinement effect reflects differences in how fluorescence and ellipsometry report "average T (g) " with confinement. With decreasing nanoscale thickness, fluorescence may slightly overweight the contribution of the free-surface layer while ellipsometry may evenly weight or underweight its contribution.
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Affiliation(s)
- S Kim
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA
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11
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The diverse effect of antiplasticizer in the molecular dynamics of an organic dye-doped polymer observed at different motional lengthscales. Eur Polym J 2009. [DOI: 10.1016/j.eurpolymj.2009.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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12
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Passaglia E, Bertoldo M, Ciardelli F, Prevosto D, Lucchesi M. Evidences of macromolecular chains confinement of ethylene–propylene copolymer in organophilic montmorillonite nanocomposites. Eur Polym J 2008. [DOI: 10.1016/j.eurpolymj.2008.02.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Serghei A, Huth H, Schick C, Kremer F. Glassy Dynamics in Thin Polymer Layers Having a Free Upper Interface. Macromolecules 2008. [DOI: 10.1021/ma702381t] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. Serghei
- Institute for Experimental Physics I, University of Leipzig, 04103 Leipzig, Germany, and Physics Department, University of Rostock, 18051 Rostock, Germany
| | - H. Huth
- Institute for Experimental Physics I, University of Leipzig, 04103 Leipzig, Germany, and Physics Department, University of Rostock, 18051 Rostock, Germany
| | - C. Schick
- Institute for Experimental Physics I, University of Leipzig, 04103 Leipzig, Germany, and Physics Department, University of Rostock, 18051 Rostock, Germany
| | - F. Kremer
- Institute for Experimental Physics I, University of Leipzig, 04103 Leipzig, Germany, and Physics Department, University of Rostock, 18051 Rostock, Germany
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Napolitano S, Wübbenhorst M. Dielectric Signature of a Dead Layer in Ultrathin Films of a Nonpolar Polymer. J Phys Chem B 2007; 111:9197-9. [PMID: 17637053 DOI: 10.1021/jp072868i] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Extremely thin films of poly(styrene) (h<or=6 nm), in the geometry of "model" nanocomposites, show a continuous increase of the capacitance with temperature. This phenomenon is discussed in terms of a gradual defreezing of the interfacial zone between the so-called dead layer and the bulk. Such a mechanism shows a strong analogy to the dielectric response of the rigid amorphous fraction in semicrystalline materials. The defreezing process, foregoing the dynamic glass transition, is responsible for the temperature dependence of the deviations from bulk behavior.
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Affiliation(s)
- Simone Napolitano
- Laboratory for Acoustics and Thermal Physics, Department of Physics and Astronomy, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
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15
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Gross S, Camozzo D, Di Noto V, Armelao L, Tondello E. PMMA: A key macromolecular component for dielectric low-κ hybrid inorganic–organic polymer films. Eur Polym J 2007. [DOI: 10.1016/j.eurpolymj.2006.12.012] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Napolitano S, Prevosto D, Lucchesi M, Pingue P, D'Acunto M, Rolla P. Influence of a reduced mobility layer on the structural relaxation dynamics of aluminum capped ultrathin films of poly(ethylene terephthalate). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:2103-9. [PMID: 17279701 DOI: 10.1021/la062229j] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The structural dynamics of ultrathin polymer films of poly(ethylene terephthalate) capped between aluminum electrodes have been investigated by dielectric relaxation spectroscopy. A deviation from bulk behavior, appearing as an increase of the relaxation time at a fixed temperature, is observed for films of thickness below 35 nm. The slowing down acts as a constant shift factor independent from the temperature, and the fragility is constant. The interfacial energy between aluminum and poly(ethylene terephthalate) is calculated to be 3 mJ/m2, confirming a strong interaction between polymer and substrate, which leads to the presence of a layer characterized by a reduced mobility at their interfaces. We proposed a mathematical schematization of a multylayer model that allowed qualitative reproduction of the observed thickness dependences of the static and dynamic properties. In terms of such a model, the upper limit for the thickness of the reduced mobility layer was estimated as 20 nm. The conditions to extend the proposed model to different observables are finally suggested.
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Affiliation(s)
- Simone Napolitano
- polyLab e Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, Pisa, Italy
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17
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Relaxation in poly(alkyl methacrylate)s: Change of intermolecular coupling with molecular structure, tacticity, molecular weight, copolymerization, crosslinking, and nanoconfinement. POLYMER 2006. [DOI: 10.1016/j.polymer.2006.06.072] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Ngai K. Interpreting the dynamics of nano-confined glass-formers and thin polymer films: Importance of starting from a viable theory for the bulk. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/polb.20923] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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19
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Serghei A, Mikhailova Y, Eichhorn KJ, Voit B, Kremer F. Discrepancies in the characterization of the glass transition in thin films of hyperbranched polyesters. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/polb.20929] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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20
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Dielectric spectroscopy using dielectric probes: a new approach to study glass transition dynamics in immiscible apolar polymer blends. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.04.095] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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21
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Kalogeras IM, Neagu ER. Interplay of surface and confinement effects on the molecular relaxation dynamics of nanoconfined poly(methyl methacrylate) chains. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2004; 14:193-204. [PMID: 15254839 DOI: 10.1140/epje/i2004-10015-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The thermally stimulated current (TSC) signatures of the primary (alpha) transition and its precursor, the Johary-Goldstein (beta) relaxation, are used to probe effects of nanoconfinement on the dielectric relaxation dynamics of poly(methyl methacrylate) (PMMA) radically polymerised in situ 50 angstroms mean pore size silica-gel. Nanoconfinement leads to a broadened and low-temperature-shifted beta band (peaking at Tbeta, with deltaTbeta = T(conf.)beta - T(bulk)beta = -15 degrees C for a heating rate of 5 deg/min), signifying the occurrence of faster relaxing moieties compared to the bulk-like PMMA film. Furthermore, both TSCs and differential scanning calorimetry (DSC) estimate a rise of the glass transition temperature for the confined phase ([Formula: see text]= +13 degrees C) and an increased width for the corresponding transition signals, relative to the signals in the bulk. Simple free-volume and entropy models seem inadequate to provide a collective description of the above perturbations. The observation of a spatial heterogeneity regarding the relaxation dynamics is discussed in terms of the presence of a motional gradient, with less mobile segments near the interface and more mobile segments in the core, and the interplay of adsorption ( e.g., strong physical interactions that slow down molecular mobilities) and confinement effects ( e.g., lower entanglements concentration and local density fluctuations that provide regions of increased free space). The results suggest that in the case of high-molecular-weight polymers confined in small-pore systems, adsorption effects have considerable bearing on the glass transition phenomenon whereas confinement primarily influences side-chains' rotational mobilities. The confinement effect is expected to dominate over adsorption for PMMA phases occluded in higher pore sizes and silanised walls.
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Affiliation(s)
- I M Kalogeras
- Department of Physics, Section of Solid State Physics, University of Athens, Panepistimiopolis, 157 84, Zografos, Greece.
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