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Main Title: Calorimetric evidence for a mobile surface layer in ultrathin polymeric films: poly(2-vinyl pyridine)
Author(s): Madkour, Sherif
Yin, Huajie
Füllbrandt, Marieke
Schönhals, Andreas
Type: Article
Language Code: en
Abstract: Specific heat spectroscopy was used to study the dynamic glass transition of ultrathin poly(2-vinyl pyridine) films (thicknesses: 405-10 nm). The amplitude and the phase angle of the differential voltage were obtained as a measure of the complex heat capacity. In a traditional data analysis, the dynamic glass transition temperature T-g is estimated from the phase angle. These data showed no thickness dependency on T-g down to 22 nm (error of the measurement of +/- 3 K). A derivative-based method was established, evidencing a decrease in T-g with decreasing thickness up to 7 K, which can be explained by a surface layer. For ultrathin films, data showed broadening at the lower temperature side of the spectra, supporting the existence of a surface layer. Finally, temperature dependence of the heat capacity in the glassy and liquid states changes with film thickness, which can be considered as a confinement effect.
Issue Date: 2015
Date Available: 25-Oct-2017
DDC Class: 530 Physik
Sponsor/Funder: DFG, Scho-470/20-1, Template confinement effects on discotic liquid-crystals
Journal Title: Soft matter
Publisher: Royal Society of Chemistry
Publisher Place: Cambridge
Volume: 11
Issue: 40
Publisher DOI: 10.1039/c5sm01558h
Page Start: 7942
Page End: 7952
EISSN: 1744-6848
ISSN: 1744-683X
Notes: Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
Appears in Collections:Inst. Chemie » Publications

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