Conjectures on the glass transition of polymers in confined geometries

McCoy, John D.; Curro, John G.

doi:10.1063/1.1481379

Cited by 81 publications

(70 citation statements)

References 24 publications

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“…For the moment it is not clear to us how this theory has to be modified in order to rationalize the results found in this work. Of course it is probably possible to use some phenomenological theories in order to describe these results [80,81,82] but having a theory at hand that allows a full microscopic calculation would certainly be much more preferable.…”

Section: Discussionmentioning

confidence: 99%

The Relaxation Dynamics of a Supercooled Liquid Confined by Rough Walls

2004

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We present the results of molecular dynamics computer simulations of a binary Lennard-Jones liquid confined between two parallel rough walls. These walls are realized by frozen amorphous configurations of the same liquid and therefore the structural properties of the confined fluid are identical to the ones of the bulk system. Hence this setup allows us to study how the relaxation dynamics is affected by the pure effect of confinement, i.e. if structural changes are completely avoided. We find that the local relaxation dynamics is a strong function of z, the distance of the particles from the wall, and that close to the surface the typical relaxation times are orders of magnitude larger than the ones in the bulk. Because of the cooperative nature of the particle dynamics, the slow dynamics also affects the dynamics of the particles for large values of z. Using various empirical laws, we are able to parameterize accurately the z−dependence of the generalized incoherent intermediate scattering function Fs(q, z, t) and also the spatial dependence of structural relaxation times. These laws allow us to determine various dynamical length scales and we find that their temperature dependence is compatible with an Arrhenius law. Furthermore, we find that at low temperatures time and space dependent correlation function fulfill a generalized factorization property similar to the one predicted by mode-coupling theory for bulk systems. For thin films and/or at sufficiently low temperatures, we find that the relaxation dynamics is influenced by the two walls in a strongly non-linear way in that the slowing down is much stronger than the one expected from the presence of only one confining wall. Finally we study the average dynamics of all liquid particles and find that the data can be described very well by a superposition of two relaxation processes that have clearly separated time scales. Since this is in contrast with the result of our analysis of the local dynamics, we argue that a correct interpretation of experimental data can be rather difficult.

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Section: Discussionmentioning

confidence: 99%

The Relaxation Dynamics of a Supercooled Liquid Confined by Rough Walls

2004

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“…Polymers filled with very small nanoparticles (d < 15 nm) have been studied in great detail both theoretically and experimentally in recent years and a number of unusual results have been reported [1][2][3][4][5][6][7][8]. While conventional fillers (d ≥ 50 nm) reinforce polymer matrices regardless of the polymer-particle interaction, nanoparticles have shown the ability to either reinforce or plasticize polymer matrices depending on their size and the interfacial interaction between the polymer and the nanoparticle.…”

Section: Introductionmentioning

confidence: 99%

Miscibility and viscoelastic properties of acrylic polyhedral oligomeric silsesquioxane–poly(methyl methacrylate) blends

Kopesky¹,

Haddad²,

McKinley³

et al. 2005

Polymer

150

115

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“…To maintain brevity, we avoid elaborating the algebraic details that accompany these calculations, and instead quote the following three equivalent results: (11) and (12). As can be seen, the shift of the IG transition is approximately inversely proportional to film thickness down to molecular length scales.…”

Section: Ideal Glass Transition Of the Ssmf Fluid Filmmentioning

confidence: 99%

Ideal glass transitions in thin films: An energy landscape perspective

Truskett

Ganesan

2003

The Journal of Chemical Physics

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We introduce a mean-field model for the potential energy landscape of a thin fluid film confined between parallel substrates. The model predicts how the number of accessible basins on the energy landscape and, consequently, the film's ideal glass transition temperature depend on bulk pressure, film thickness, and the strength of the fluid-fluid and fluid-substrate interactions. The predictions are in qualitative agreement with the experimental trends for the kinetic glass transition temperature of thin films, suggesting the utility of landscape-based approaches for studying the behavior of confined fluids.

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Conjectures on the glass transition of polymers in confined geometries

Cited by 81 publications

References 24 publications

The Relaxation Dynamics of a Supercooled Liquid Confined by Rough Walls

The Relaxation Dynamics of a Supercooled Liquid Confined by Rough Walls

Miscibility and viscoelastic properties of acrylic polyhedral oligomeric silsesquioxane–poly(methyl methacrylate) blends

Ideal glass transitions in thin films: An energy landscape perspective

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