Glass transition in vapor deposited thin films of toluene

León-Gutiérrez, E.; García, G.; Clavaguera-Mora, M.T.; Rodríguez‐Viejo, J.

doi:10.1016/j.tca.2009.05.016

Cited by 63 publications

(71 citation statements)

References 28 publications

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“…37,43 Due to 5 orders of magnitude difference between heating rates in our FSC experiments and those in traditional DSC experiments, tens of the degrees increase in T g is typical. 18,[44][45][46] As we explain immediately below, in the case of water, such a shift in T g toward higher values must facilitate greater sensitivity toward glass endotherms. In the case of benzene films, the lack of endo-and exotherms is due to C 6 H 6 crystallization during deposition.…”

Section: ' Experimental Sectionmentioning

confidence: 93%

Bulk and Interfacial Glass Transitions of Water

2011

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Fast scanning calorimetry (FSC) was employed to investigate glass softening dynamics in bulk-like and ultrathin glassy water films. Bulk-like water samples were prepared by vapor-deposition on the surface of a tungsten filament near 140 K where vapor-deposition results in low enthalpy glassy water films. The vapor-deposition approach was also used to grow multiple nanoscale (approximately 50 nm thick) water films alternated with benzene and methanoic films of similar dimensions. When heated from cryogenic temperatures, the ultrathin water films underwent a well manifested glass softening transition at temperatures 20 K below the onset of crystallization. However, no such transition was observed in bulk-like samples prior to their crystallization. These results indicate that thin-film water demonstrates glass softening dynamics that are dramatically distinct from those of the bulk phase. We attribute these differences to water's interfacial glass transition, which occurs at temperatures tens of degrees lower than that in the bulk. Implications of these findings for past studies of glass softening dynamics in various glassy water samples are discussed.

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Section: ' Experimental Sectionmentioning

confidence: 93%

Bulk and Interfacial Glass Transitions of Water

2011

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“…For deposition temperatures in the vicinity of 0.85 T g vapordeposited glasses exhibit low enthalpy [5,7,34,46,50], the heat capacity of the glass drops by about 4% [50][51][52][53], high density (1.3% denser for TNB) [10], high mechanical moduli (up to 15% increased) [54,55] and they can resist water uptake [44]. 2D WAXS measurements by Dawson et al.…”

Section: Two Different Observations Of the Stability Of Vapor-depositmentioning

confidence: 99%

In situ investigation of vapor-deposited glasses of toluene and ethylbenzene via alternating current chip-nanocalorimetry

Ahrenberg

Chua

Whitaker

et al. 2013

The Journal of Chemical Physics

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Vapor-deposited glasses of toluene and ethylbenzene have been characterized by in situ ac chip-nanocalorimetry. The high sensitivity of this method allows the detection of small changes in the heat capacity of nanogram size samples. We observe that vapor-deposited glasses have up to 4% lower heat capacities than the ordinary glass. The largest heat capacity decrease and the most kinetically stable glasses of toluene and ethylbenzene are observed in a range of deposition temperatures between 0.75 Tg and 0.96 Tg. Compared to larger molecules, deposition rate has a minor influence on the kinetic stability of these glasses. For both toluene and ethylbenzene, the kinetic stability is strongly correlated with the heat capacity decrease for deposition temperatures above 0.8 Tg. In addition, ac-nanocalorimetry was used to follow the isothermal transformation of the stable glasses into the supercooled liquid at temperatures slightly above Tg. Toluene and ethylbenzene stable glasses exhibit a constant transformation rate which is consistent with the growth front mechanism recently demonstrated for tris-naphthylbenzene and indomethacin. The kinetic stability of the most stable toluene and ethylbenzene glasses is comparable to that observed for other stable glasses formed by vapor deposition.

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“…500 Ks −1 , was developed by Hager [57] and, even for rates up to 10 7 Ks −1 , by Allen and co-workers [30,58,59]. Similar approaches were used to study the behavior of metastable materials like vapor deposited films [60][61][62][63][64][65]. But, on the other hand, the investigation of metastable phase formation is possible only if the same high-controlled cooling rates are available too.…”

Section: Fast Scanning Calorimetric Techniquesmentioning

confidence: 99%

1. Influence of Thermal Prehistory on Crystal Nucleation and Growth in Polymers

Schick¹,

Zhuravlev²,

Androsch³

et al. 2014

Glass

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Observations regarding the effect of thermal history of crystallizing polymer melts onto the outcome of crystal nucleation and growth processes are investigated experimentally. Some results can be at least on a qualitative basis explained by classical nucleation theory (CNT) while others are not easy to understand in the framework of CNT. The origin of the respective problems and possible extensions of CNT to overcome them are briefly discussed. We chose polymers as model systems because they allow one a separate investigation of nucleation and growth processes in a wide temperature and time range. Furthermore they are well suited to be analyzed experimentally by the recently developed fast scanning calorimetry. In particular, by applying fast scanning calorimetry we are able to investigate processes in bulk samples and do not need to use droplets to study homogeneous nucleation kinetics. Fast scanning calorimetry enables us to observe homogeneous nucleation in materials crystallizing relatively fast like most of the industrial relevant semicrystalline polymers. Quantitative analysis allowed us to judge the nucleation efficiency of additives in the whole range of temperatures, where polymers crystallize. Besides the observed nucleation and growth below the glass transition information about the nucleation activity of small crystals grown at different temperatures relative to the cold-crystallization temperature range were obtained. Finally we show how relaxation of the under-cooled melt (glass) influences homogeneous nucleation. These data may serve as input for a more general description of the interplay of nucleation-growth and relaxation processes within the framework of a structural order-parameter model.

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Glass transition in vapor deposited thin films of toluene

Cited by 63 publications

References 28 publications

Bulk and Interfacial Glass Transitions of Water

Bulk and Interfacial Glass Transitions of Water

In situ investigation of vapor-deposited glasses of toluene and ethylbenzene via alternating current chip-nanocalorimetry

1. Influence of Thermal Prehistory on Crystal Nucleation and Growth in Polymers

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