Glass Transition in Liquids: Two versus Three-Dimensional Confinement

Barut, G.; Pissis, P.; Pelster, R.; Nimtz, G.

doi:10.1103/physrevlett.80.3543

Cited by 144 publications

(103 citation statements)

References 26 publications

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“…This is counterintuitive given the argument above that cylindrical confinement is "stronger" than parallel-plate confinement. This trend is the opposite of that seen for small molecule liquids [55]. Future experiments may be able to elaborate on the question for colloids: at one extreme, particle motion could be studied in a half-infinite system near a wall, whereas at the other extreme, particle motion could be studied in a spherical pore.…”

Section: Discussionmentioning

confidence: 99%

Slow dynamics in cylindrically confined colloidal suspensions

Saklayen

Hunter

Edmond

et al. 2013

AIP Conference Proceedings

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Abstract. We study bidisperse colloidal suspensions confined within glass microcapillary tubes to model the glass transition in confined cylindrical geometries. We use high speed three-dimensional confocal microscopy to observe particle motions for a wide range of volume fractions and tube radii. Holding volume fraction constant, we find that particles move slower in thinner tubes. The tube walls induce a gradient in particle mobility: particles move substantially slower near the walls. This suggests that the confinement-induced glassiness may be due to an interfacial effect.

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Section: Discussionmentioning

confidence: 99%

Slow dynamics in cylindrically confined colloidal suspensions

Saklayen

Hunter

Edmond

et al. 2013

AIP Conference Proceedings

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“…Donth [18] relates the distribution of relaxation times in systems approaching their glass transition to equilibrium thermodynamic fluctuations having a characteristic size of ∼ 3 nm at T g . Thermodynamic measurements on orthoterphenyl [19], and dielectric measurements on salol [20], Nmethyl-ǫ-caprolactan and propylene glycol [21], showed a shift in T g due to confinement in pores of the order of a few nanometers. Mountain [3] showed that the size of regions that support shear stress in a simulation of a glass-forming mixture of soft spheres grows with decreasing temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…There have been numerous attempts to indirectly measure a characteristic length scale over which molecular motions are correlated at the glass transition both in experiments [18][19][20][21] and in simulations [3,22]. Donth [18] relates the distribution of relaxation times in systems approaching their glass transition to equilibrium thermodynamic fluctuations having a characteristic size of ∼ 3 nm at T g .…”

Section: Introductionmentioning

confidence: 99%

Spatial correlations of mobility and immobility in a glass-forming Lennard-Jones liquid

et al. 1999

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Using extensive molecular dynamics simulations of an equilibrium, glass-forming Lennard-Jones mixture, we characterize in detail the local atomic motions. We show that spatial correlations exist among particles undergoing extremely large ("mobile") or extremely small ("immobile") displacements over a suitably chosen time interval. The immobile particles form the cores of relatively compact clusters, while the mobile particles move cooperatively and form quasi-one-dimensional, string-like clusters. The strength and length scale of the correlations between mobile particles are found to grow strongly with decreasing temperature, and the mean cluster size appears to diverge at the mode-coupling critical temperature. We show that these correlations in the particle displacements are related to equilibrium fluctuations in the local potential energy and local composition.

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“…If CRR's do exist and grow with decreasing temperature the dynamics should differ from the bulk behavior as soon as the size of the CRR's at a given temperature becomes comparable to the system size. Indeed, almost all experiments on glass formers confined to porous host material [6][7][8][9][10][11][12] and supported (or even free standing) films [13][14][15][16][17] do indeed show a relaxation dynamics that differs from the one in the bulk. However, so far it has not been possible to give a conclusive interpretation of experimental results, since, e.g., one sometimes finds that the dynamics in confined systems is faster than the one of the bulk, whereas in other systems it is slower (see, e.g., [8,10]).…”

mentioning

confidence: 99%

“…(Similar experimental results can be found in Refs. [7,8]). Also note that the increase of the spectra at low ω is related to the Maxwell-Wagner polarization of the sample [9] which has nothing to do with the structural relaxation of the system.)…”

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confidence: 99%

Cooperative motion and growing length scales in supercooled confined liquids

2002

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Abstract. -Using molecular dynamics simulations we investigate the relaxation dynamics of a supercooled liquid close to a rough as well as close to a smooth wall. For the former situation the relaxation times increase strongly with decreasing distance from the wall whereas in the second case they strongly decrease. We use this dependence to extract various dynamical length scales and show that they grow with decreasing temperature. By calculating the frequency dependent average susceptibility of such confined systems we show that the experimental interpretation of such data is very difficult.Motivation. -The details of the mechanism giving rise to the dramatic slowing down of the dynamics of glass-forming liquids upon supercooling are still unknown (see, e.g. [1]). Although the mode-coupling theory of the glass transition allows to rationalize many features of the relaxation dynamics of these systems [2], the answers to certain important questions (e.g. the relaxation dynamics at low temperatures) are still unknown. A further popular approach is the phenomenological concept of "cooperativity", introduced by Kauzmann [3], and Adam and Gibbs [4]. A typical example of this cooperativity is the so-called "cage-effect", i.e. the fact that in a dense liquid each particle is surrounded by neighboring particles which form a temporary cage. In order to allow the particle to change its position the cage has to open up. However, each of the particles of the cage is itself also caged and hence can move only if other particles make room. Therefore one can conclude that the particle motion is collective and there exist "cooperatively rearranging regions" (CRR's) within the liquid. The typical size of a CRR is postulated to grow with decreasing temperature, hence "rationalizing" the slowing down of the dynamics [4,5].Experimentally it is difficult to test the concept of the CRR's since usually one does not have direct access to the dynamics of single particles. Therefore many studies have focused on investigating systems in spatial confinement. If CRR's do exist and grow with decreasing temperature the dynamics should differ from the bulk behavior as soon as the size of the CRR's at a given temperature becomes comparable to the system size. Indeed, almost all experiments on glass formers confined to porous host material [6][7][8][9][10][11][12] and supported (or even free standing) films [13][14][15][16][17] do indeed show a relaxation dynamics that differs from the one in the bulk. However, so far it has not been possible to give a conclusive interpretation of

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Glass Transition in Liquids: Two versus Three-Dimensional Confinement

Cited by 144 publications

References 26 publications

Slow dynamics in cylindrically confined colloidal suspensions

Slow dynamics in cylindrically confined colloidal suspensions

Spatial correlations of mobility and immobility in a glass-forming Lennard-Jones liquid

Cooperative motion and growing length scales in supercooled confined liquids

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