1
|
Manz AS, Paeng K, Kaufman LJ. Single molecule studies reveal temperature independence of lifetime of dynamic heterogeneity in polystyrene. J Chem Phys 2018; 148:204508. [PMID: 29865823 DOI: 10.1063/1.5031131] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Polymeric systems close to their glass transition temperature are known to exhibit heterogeneous dynamics that evolve both over time and space, comparable to the dynamics of small molecule glass formers. It remains unclear how temperature influences the degree of heterogeneous dynamics in such systems. In the following report, a fluorescent perylene dicarboximide probe molecule that reflects the full breadth of heterogeneity of the host was used to examine the temperature dependence of the dynamic heterogeneity lifetime in polystyrene at several temperatures ranging from the glass transition to 10 K above this temperature via single molecule microscopy. Contrary to prior reports, no apparent temperature dependence of time scales associated with dynamic heterogeneity was detected; indeed, the probe molecules report characteristic dynamic heterogeneity lifetimes 100-300 times the average alpha-relaxation time (τα) of the polystyrene host at all temperatures studied.
Collapse
Affiliation(s)
- Alyssa S Manz
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Keewook Paeng
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Laura J Kaufman
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| |
Collapse
|
2
|
Krause S, Neumann M, Fröbe M, Magerle R, von Borczyskowski C. Monitoring Nanoscale Deformations in a Drawn Polymer Melt with Single-Molecule Fluorescence Polarization Microscopy. ACS NANO 2016; 10:1908-1917. [PMID: 26831762 DOI: 10.1021/acsnano.5b05729] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Elongating a polymer melt causes polymer segments to align and polymer coils to deform along the drawing direction. Despite the importance of this molecular response for understanding the viscoelastic properties and relaxation behavior of polymeric materials, studies on the single-molecule level are rare and were not performed in real time. Here we use single-molecule fluorescence polarization microscopy for monitoring the position and orientation of single fluorescent perylene diimide molecules embedded in a free-standing thin film of a polymethyl acrylate (PMA) melt with a time resolution of 500 ms during the film drawing and the subsequent stress relaxation period. The orientation distribution of the perylene diimide molecules is quantitatively described with a model of rod-like objects embedded in a uniaxially elongated matrix. The orientation of the fluorescent probe molecules is directly coupled to the local deformation of the PMA melt, which we derive from the distances between individual dye molecules. In turn, the fluorescence polarization monitors the shape deformation of the polymer coils on a length scale of 5 nm. During stress relaxation, the coil shape relaxes four times more slowly than the mechanical stress. This shows that stress relaxation involves processes on length scales smaller than a polymer coil. Our work demonstrates how optical spectroscopy and microscopy can be used to study the coupling of individual fluorescent probe molecules to their embedding polymeric matrix and to an external mechanical stimulus on the single-molecule level.
Collapse
Affiliation(s)
- Stefan Krause
- Fakultät für Naturwissenschaften, Technische Universität Chemnitz , 09107 Chemnitz, Germany
| | - Martin Neumann
- Fakultät für Naturwissenschaften, Technische Universität Chemnitz , 09107 Chemnitz, Germany
| | - Melanie Fröbe
- Fakultät für Naturwissenschaften, Technische Universität Chemnitz , 09107 Chemnitz, Germany
| | - Robert Magerle
- Fakultät für Naturwissenschaften, Technische Universität Chemnitz , 09107 Chemnitz, Germany
| | | |
Collapse
|
3
|
DIVYA KIZHMURIP, BERTOCCHI MICHAELJ, WEISS RICHARDG. Effects of temperature and CO2 pressure on the emission of N,N′-dialkylated perylene diimides in poly(alkyl methacrylate) films. Are guest-host alkyl group interactions important? J CHEM SCI 2016. [DOI: 10.1007/s12039-015-1009-5] [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]
|
4
|
Abstract
Much of the interesting behavior that has been observed in supercooled liquids appears to be related to dynamic heterogeneity, the presence of distinct dynamic environments - with no apparent underlying structural basis - in these systems. To most directly interrogate these environments, proposed to span regions just a few nanometers across, molecular length scale probes are required. Single molecule fluorescent microscopy was introduced to the field a decade ago and has provided strong evidence of dynamic heterogeneity in supercooled systems. However, only more recently has the full set of challenges associated with interpreting results of these experiments been described. With a fuller understanding of these challenges in hand, single molecule measurements can be employed to provide a more precise picture of dynamic heterogeneity in supercooled liquids and other complex systems. In this tutorial review, experimental and data analysis details are presented for the most commonly employed single molecule approach to studying supercooled liquids, the measurement of rotational dynamics of single molecule probes. Guidance is provided in experimental set-up and probe selection, with a focus on choices that affect data interpretation and probe sensitivity to dynamic heterogeneity.
Collapse
Affiliation(s)
- Keewook Paeng
- Department of Chemistry, Columbia University, New York, NY 10027, USA.
| | | |
Collapse
|
5
|
Hoang DT, Paeng K, Park H, Leone LM, Kaufman LJ. Extraction of Rotational Correlation Times from Noisy Single Molecule Fluorescence Trajectories. Anal Chem 2014; 86:9322-9. [PMID: 25151855 DOI: 10.1021/ac502575k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Dat Tien Hoang
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Keewook Paeng
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Heungman Park
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Lindsay M. Leone
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Laura J. Kaufman
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| |
Collapse
|
6
|
Araoz B, Carattino A, Täuber D, von Borczyskowski C, Aramendia PF. Influence of the Glass Transition on Rotational Dynamics of Dyes in Thin Polymer Films: Single-Molecule and Ensemble Experiments. J Phys Chem A 2014; 118:10309-17. [DOI: 10.1021/jp500272y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Beatriz Araoz
- INQUIMAE
and Dept. Química Inorgánica Analítica y Química
Física. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Ciudad de Buenos Aires, Argentina
| | - Aquiles Carattino
- INQUIMAE
and Dept. Química Inorgánica Analítica y Química
Física. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Ciudad de Buenos Aires, Argentina
| | - Daniela Täuber
- Institute
of Physics and nanoMA, Technische Universität Chemnitz, 09107 Chemnitz, Germany
| | | | - Pedro F. Aramendia
- INQUIMAE
and Dept. Química Inorgánica Analítica y Química
Física. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Ciudad de Buenos Aires, Argentina
- Centro
de Investigaciones en Bionanociencias, CIBION-CONICET, Godoy Cruz 2390, 1425 Ciudad de Buenos Aires, Argentina
- Dept. Química Inorgánica
Analítica
y Química Física. Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 2, Ciudad Universitaria, C1428EHA Ciudad de Buenos Aires, Argentina
| |
Collapse
|
7
|
Kaufman LJ. Heterogeneity in Single-Molecule Observables in the Study of Supercooled Liquids. Annu Rev Phys Chem 2013; 64:177-200. [DOI: 10.1146/annurev-physchem-040412-110033] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bulk approaches to studying heterogeneous systems obscure important details, as they report average behavior rather than the distribution of behaviors in such environments. Small-molecule and polymeric supercooled liquids, which display heterogeneity in their dynamics without an underlying structural heterogeneity that sets those dynamics, are important constituents of this category of condensed matter systems. A variety of approaches have been devised to unravel ensemble averaging in supercooled liquids. This review focuses on the ultimate subensemble approach, single-molecule measurements, as they have been applied to the study of supercooled liquids. We detail how three key experimental observables (single-molecule probe rotation, translation, and fluorescence lifetime) have been employed to provide detail on dynamic heterogeneity in supercooled liquids. Special attention is given to the potential for, but also the challenges in, discriminating spatial and temporal heterogeneity and detailing the length scales and timescales of heterogeneity in these systems.
Collapse
Affiliation(s)
- Laura J. Kaufman
- Department of Chemistry, Columbia University, New York, NY 10027
| |
Collapse
|
8
|
Saxton MJ. Wanted: a positive control for anomalous subdiffusion. Biophys J 2012; 103:2411-22. [PMID: 23260043 DOI: 10.1016/j.bpj.2012.10.038] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 09/23/2012] [Accepted: 10/10/2012] [Indexed: 11/25/2022] Open
Abstract
Anomalous subdiffusion in cells and model systems is an active area of research. The main questions are whether diffusion is anomalous or normal, and if it is anomalous, its mechanism. The subject is controversial, especially the hypothesis that crowding causes anomalous subdiffusion. Anomalous subdiffusion measurements would be strengthened by an experimental standard, particularly one able to cross-calibrate the different types of measurements. Criteria for a calibration standard are proposed. First, diffusion must be anomalous over the length and timescales of the different measurements. The length-scale is fundamental; the time scale can be adjusted through the viscosity of the medium. Second, the standard must be theoretically well understood, with a known anomalous subdiffusion exponent, ideally readily tunable. Third, the standard must be simple, reproducible, and independently characterizable (by, for example, electron microscopy for nanostructures). Candidate experimental standards are evaluated, including obstructed lipid bilayers; aqueous systems obstructed by nanopillars; a continuum percolation system in which a prescribed fraction of randomly chosen obstacles in a regular array is ablated; single-file diffusion in pores; transient anomalous subdiffusion due to binding of particles in arrays such as transcription factors in randomized DNA arrays; and computer-generated physical trajectories.
Collapse
Affiliation(s)
- Michael J Saxton
- Department of Biochemistry and Molecular Medicine, University of California at Davis, Davis, California, USA.
| |
Collapse
|
9
|
Oba T, Vacha M. Relaxation in Thin Polymer Films Mapped across the Film Thickness by Astigmatic Single-Molecule Imaging. ACS Macro Lett 2012; 1:784-788. [PMID: 35607105 DOI: 10.1021/mz3002269] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have studied relaxation processes in thin supported films of poly(methyl acrylate) at the temperature corresponding to 13 K above the glass transition by monitoring the reorientation of single perylenediimide molecules doped into the films. The axial position of the dye molecules across the thickness of the film was determined with a resolution of 12 nm by analyzing astigmatic fluorescence images. The average relaxation times of the rotating molecules do not depend on the overall thickness of the film between 20 and 110 nm. The relaxation times also do not show any dependence on the axial position within the films for the film thickness between 70 and 110 nm. In addition to the rotating molecules we observed a fraction of spatially diffusing molecules and completely immobile molecules. These molecules indicate the presence of thin (<5 nm) high-mobility surface layer and low-mobility layer at the interface with the substrate.
Collapse
Affiliation(s)
- Tatsuya Oba
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama 2-12-1-S8,
Meguro-ku, Tokyo 152-8552, Japan
| | - Martin Vacha
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama 2-12-1-S8,
Meguro-ku, Tokyo 152-8552, Japan
| |
Collapse
|
10
|
Turgeman L, Fixler D. Short time behavior of fluorescence intensity fluctuations in single molecule polarization sensitive experiments. OPTICS EXPRESS 2012; 20:9276-9283. [PMID: 22513639 DOI: 10.1364/oe.20.009276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Recent developments in the field of single molecule orientation imaging have led us to devise a simple framework for analyzing fluorescence intensity fluctuations in single molecule polarization sensitive experiments. Based on the new framework, rotational dynamics of individual molecules are quantified, in this paper, from the short time behavior of the time averaged fluorescence intensity fluctuation trajectories. The suggested model can be applied in single molecule fluorescence fluctuations experiments to extract accurate expectation values of photon counts during very short integration time in which rotational diffusion is likely not to be averaged out.
Collapse
Affiliation(s)
- Lior Turgeman
- Faculty of Engineering and Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat Gan 52900, Israel.
| | | |
Collapse
|
11
|
Uvarov MN, Kulik LV, Doktorov AB, Dzuba SA. Isotropic reorientations of fullerene C70 triplet molecules in solid glassy matrices revealed by light-induced electron paramagnetic resonance. J Chem Phys 2011; 135:054507. [PMID: 21823712 DOI: 10.1063/1.3618738] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Continuous-wave X-band electron paramagnetic resonance (EPR) of fullerene C(70) molecules excited to a triplet state by continuous light illumination was studied in molecular glasses of o-terphenyl and cis/trans-decaline and in the glassy polymers polymethylmethacrylate (PMMA) and polystyrene (PS). Above ∼100 K, a distinct narrowing of EPR lineshape of the triplet was observed, which was very similar for all systems studied. EPR lineshape was simulated reasonably well within a framework of a simple model of random jumps, which implies that the C(70) molecule performs isotropic orientational motion by sudden jumps of arbitrary angles. In simulations, a single correlation time τ(c) was used, varying in the range of 10(-7)-10(-8) s. Near and below 100 K electron spin echo (ESE) signals were also obtained which were found to decay exponentially. Correlation times τ(c) obtained from simulation of the EPR spectra in the slow-motion limit (τ(c) close to 10(-7) s) turned out to be in good agreement with the phase memory times T(M) of the ESE decay, which additionally supports the employed simple model. The observed motional effects provide evidence that the nanostructure of the solid glassy media of different origins is soft enough to allow a large asymmetric C(70) molecule to reorient rapidly. Except for the EPR spectra of the triplet, in the center of the spectra, a small admixture of a narrow line was also observed; its possible nature is briefly discussed.
Collapse
Affiliation(s)
- Mikhail N Uvarov
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk, Russia
| | | | | | | |
Collapse
|