Calorimetric evidence for a mobile surface layer in ultrathin polymeric films: poly(2-vinyl pyridine)

Madkour, Sherif; Yin, Huajie; Füllbrandt, Marieke; Schönhals, Andreas

doi:10.1039/c5sm01558h

Cited by 37 publications

(47 citation statements)

References 78 publications

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“…This behavior is different from that reported for the dynamic glass transition measured for identically prepared PVME/PS films, probed by SHS in the frequency range from 10 Hz to 10 4 Hz . For the method and data analysis, see refs and . The results are summarized in the relaxation map (Figure ), where the relaxation rate f p is plotted versus inverse temperature.…”

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confidence: 57%

Decoupling of Dynamic and Thermal Glass Transition in Thin Films of a PVME/PS Blend

et al. 2017

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The discussions on the nanoconfinement effect on the glass transition and glassy dynamics phenomena have yielded many open questions.Here, the thickness dependence of the thermal glass transition temperature T g therm of thin films of a PVME/PS blend is investigated by ellipsometry. Its thickness dependence was compared to that of the dynamic glass transition (measured by specific heat spectroscopy) and the deduced Vogel temperature (T 0 ). While T g therm and T 0 showed a monotonous increase, with decreasing film thickness, the dynamic glass transition temperature (T g dyn ) measured at a finite frequency showed a nonmonotonous dependence that peaks at 30 nm. This was discussed by assuming different cooperativity length scales at these temperatures, which have different sensitivities to composition and thickness. This nonmonotonous thickness dependence of T g dyn disappears for frequencies characteristic for T 0 . Further analysis of the fragility parameter showed a change in the glassy dynamics from strong to fragile, with decreasing film thickness.

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confidence: 57%

Decoupling of Dynamic and Thermal Glass Transition in Thin Films of a PVME/PS Blend

et al. 2017

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“… 106 Table 1 shows the γ Total , γ LW , and γ P values for P2VP, Al, alumina, and SiO 2 calculated from the contact angle values available in the literature. 58 , 107 , 108 One can estimate the interfacial energy between two materials, in our case, the polymer ″P″ and the substrate ″S″, as follows: 109 …”

Section: Resultsmentioning

confidence: 99%

On the Segmental Dynamics and the Glass Transition Behavior of Poly(2-vinylpyridine) in One- and Two-Dimensional Nanometric Confinement

Winkler

Unni

et al. 2021

J. Phys. Chem. B

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Geometric nanoconfinement, in one and two dimensions, has a fundamental influence on the segmental dynamics of polymer glass-formers and can be markedly different from that observed in the bulk state. In this work, with the use of dielectric spectroscopy, we have investigated the glass transition behavior of poly(2-vinylpyridine) (P2VP) confined within alumina nanopores and prepared as a thin film supported on a silicon substrate. P2VP is known to exhibit strong, attractive interactions with confining surfaces due to the ability to form hydrogen bonds. Obtained results show no changes in the temperature evolution of the α-relaxation time in nanopores down to 20 nm size and 24 nm thin film. There is also no evidence of an out-of-equilibrium behavior observed for other glass-forming systems confined at the nanoscale. Nevertheless, in both cases, the confinement effect is seen as a substantial broadening of the α-relaxation time distribution. We discussed the results in terms of the importance of the interfacial energy between the polymer and various substrates, the sensitivity of the glass-transition temperature to density fluctuations, and the density scaling concept.

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“…This increase in T g therm was traced back to the influence of an adsorbed layer, with a reduced mobility and higher T g therm . The effect of this layer becomes more pronounced with decreasing film thickness. , However, for thin films of homopolymers, investigations of the molecular mobility, e.g., by dielectric ,− and specific heat spectroscopy, , probing the α-relaxation (segmental dynamics and dynamic glass transition temperature T g dyn ) responsible for the glass transition, showed no thickness dependence of T g dyn . Please note that T g dyn is measured at temperatures above T g therm .…”

Section: Introductionmentioning

confidence: 99%

Do Interfacial Layers in Thin Films Act as an Independent Layer within Thin Films?

et al. 2020

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The thermodynamic behavior of thin Poly(vinyl methyl ether) (PVME) films including the irreversible adsorbed layer on the substrate is investigated. In the first step, the growth kinetics of the adsorbed layer was studied combining a leaching technique and atomic force microscopy. Furthermore, it was shown that there is a critical initial film thickness for the formation of a surface-filling adsorbed layer. Additionally, spectroscopic ellipsometry measurements were carried out to investigate the influence of the adsorbed layer on the glass transition temperature of the thin films. For 30 nm films and films with lower thicknesses, the influence of the adsorbed layer percolates strongly to the bulk-like layer of the film. Finally, the molecular dynamics of the adsorbed layer was studied by broadband dielectric spectroscopy, employing a nanostructured-electrode system. One process was revealed, which was assigned either to molecular fluctuations taking place in the loosely bounded part of the adsorbed layer or to the desorption/adsorption of segments at the substrate.

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Calorimetric evidence for a mobile surface layer in ultrathin polymeric films: poly(2-vinyl pyridine)

Cited by 37 publications

References 78 publications

Decoupling of Dynamic and Thermal Glass Transition in Thin Films of a PVME/PS Blend

Decoupling of Dynamic and Thermal Glass Transition in Thin Films of a PVME/PS Blend

On the Segmental Dynamics and the Glass Transition Behavior of Poly(2-vinylpyridine) in One- and Two-Dimensional Nanometric Confinement

Do Interfacial Layers in Thin Films Act as an Independent Layer within Thin Films?

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