Single-Molecule Studies of Heterogeneous Dynamics in Polymer Melts Near the Glass Transition

Deschenes, Laura A.; Bout, David A. Vanden

doi:10.1126/science.1056430

Cited by 207 publications

(187 citation statements)

References 29 publications

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“…In contrast to the trajectories at low density, dynamics at high density are clearly heterogeneous: at any given time, some particles are rotating quickly while others are essentially frozen. Similar behavior has been observed for translational motion of a probe molecule immersed in spin-facilitated models [14,15] and in poilymer films [2,3].…”

Section: Heterogeneous Dynamics and Rotational Correlation Timessupporting

confidence: 77%

“…Experimental measures of heterogeneous dynamics often probe rotational degrees of freedom. For example, Deschenes and Vandenbout [2,3] have measured the rotation of single probe molecules in a polymer film near the glass transition. Here, we investigate a kinetically constrained lattice gas model with translational and rotational degrees of freedom which captures many of the essential features seen in these experiments such as stretched exponential decay of rotational autocorrelation functions as temperature is decreased and heterogeneous distributions of exchange times.…”

Section: Introductionmentioning

confidence: 99%

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Rotational correlation and dynamic heterogeneity in a kinetically constrained lattice gas

Pan

2005

The Journal of Chemical Physics

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We study dynamical heterogeneity and glassy dynamics in a kinetically constrained lattice gas model which has both translational and rotational degrees of freedom. We find that the rotational diffusion constant tracks the structural relaxation time as density is increased whereas the translational diffusion constant exhibits a strong decoupling. We investigate distributions of exchange and persistence times for both the rotational and translational degrees of freedom and compare our results on the distributions of rotational exchange times to recent single molecule studies.

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Section: Heterogeneous Dynamics and Rotational Correlation Timessupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Rotational correlation and dynamic heterogeneity in a kinetically constrained lattice gas

Pan

2005

The Journal of Chemical Physics

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“…Individual fluorescent molecules have also been used to study dynamics in polymer hosts, reporting on the fluctuations in the local environment. Deschenes and van den Bout 22 used polarization microscopy to study the rotation of single Rhodamine 6G dopant molecules in a poly-(methacrylate) film and found that each molecule sampled several rotational time scales over the course of the measurement, switching rapidly from one to the next. Bartko and Dickson 23 have used advanced optical imaging methods to follow three-dimensional orientations of single molecules in polymers.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Optical Chromophores as Nanoscale Emitters for Single-Molecule Spectroscopy

et al. 2005

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Fluorescence imaging of single molecules at room temperature is a powerful technique for studying complex condensed phase systems and revealing structure and dynamics hidden by ensemble measurements. Successful single-molecule spectroscopic experiments rely upon strong emitters that can be detected at the level of individual copies above the relevant background signals. This Account discusses a class of nonlinear optical chromophores that not only are well-suited for single-molecule imaging but also offer additional beneficial properties such as a significant ground-state dipole moment, moderate hyperpolarizability, and sensitivity to local environment. An overview of the photophysical properties of several members of this class of molecules as well as a mechanism to help understand the environmental sensitivity is presented. Some preliminary applications of the chromophores as single-molecule reporters in cellular and polymer systems are discussed, along with detection of the emitters by two-photon fluorescence.

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“…We refer to a system as dynamically heterogeneous if it is possible to select a dynamically distinguishable subset of particles by experiment or computer simulation [20]. Simulations [21,22,23,24,25,26,27] and experiments [28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43] have demonstrated the cooperative and spatially heterogeneous nature of the liquid dynamics (for reviews of the experimental evidence for spatially heterogeneous dynamics, see, e. g., Refs. [44,45,46]).…”

Section: Introductionmentioning

confidence: 99%

Dynamical Heterogeneity and Jamming in Glass-Forming Liquids

Lacevic

Glotzer

2004

J. Phys. Chem. B

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The relationship between spatially heterogeneous dynamics (SHD) and jamming is studied in a glass-forming binary Lennard-Jones system via molecular dynamics simulations. It has been suggested by O'Hern et al. [1] that the probability distribution of interparticle forces P (F ) develops a peak at the glass transition temperature Tg, and that the large force inhomogeneities, responsible for structural arrest in granular materials, are related to dynamical heterogeneities in supercooled liquids that form glasses. It has been further suggested that "force chains" present in granular materials may exist in supercooled liquids, and may provide an order parameter for the glass transition. Our goal is to investigate the extent to which the forces experienced by particles in a glass-forming liquid are related to SHD, and compare these forces to those observed in granular materials and other glass-forming systems. Our results are summarized as follows. We find no peak in P (F ) at any temperature in our system, even below Tg. We also find that particles that have been localized for a long time are less likely to experience high relative force and that mobile particles experience higher relative forces at shorter time scales, indicating a correlation between pairwise forces and particle mobility. We construct force chains based on the magnitude of pairwise forces. We find that force chains constructed in this manner are composed of both localized and mobile particles, therefore there is no one-to-one correspondence between force chains as defined here and locally mobile or immobile regions of the liquid. We also find that force chains do not play the same role as force chains in granular materials, but may indicate a difference in the evolution of the local environment of particles with different mobility. We also discuss a possible relationship between force chains found here and the development of string-like motion found in other glass-forming liquids [2,3].

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Single-Molecule Studies of Heterogeneous Dynamics in Polymer Melts Near the Glass Transition

Cited by 207 publications

References 29 publications

Rotational correlation and dynamic heterogeneity in a kinetically constrained lattice gas

Rotational correlation and dynamic heterogeneity in a kinetically constrained lattice gas

Nonlinear Optical Chromophores as Nanoscale Emitters for Single-Molecule Spectroscopy

Dynamical Heterogeneity and Jamming in Glass-Forming Liquids

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