Berlin 2015 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 4: Thin Film Characterisation II: Structure Analysis and Composition
DS 4.13: Vortrag
Montag, 16. März 2015, 18:15–18:30, H 0111
Dynamic glass transition of ultrathin poly(2-vinyl pyridine) films — •Sherif Madkour1, Huajie Yin1, Marieke Fuellbrandt1,2, and Andreas Schoenhals1 — 1BAM Bundesanstalt für Materialforschung und -prüfung, Berlin, Germany — 2Stranski-Laboratorium fur Physikalische und Theoretische Chemie/ Institut fu*r Chemie, Technische Universität Berlin, Berlin, Germany
Specific heat spectroscopy utilizing differential AC-chip calorimetry in the frequency range from 1 Hz to 2 kHz with a sensitivity of pJ/K was employed to study the dynamic glass transition behavior of ultrathin poly(2-vinyl pyridine) (P2VP) films with thicknesses from 400 down to 10 nm. The amplitude and the phase angle of the complex differential voltage as a measure of the complex heat capacity were obtained as a function of temperature at given frequencies simultaneously. Both spectra were used to determine the dynamic glass transition temperature as a function of the film thickness. As a main result, no thickness dependence of the dynamic glass transition temperature or its width was observed for P2VP thin films down to a film thickness of 10 nm, within the experimental uncertainty of *3 K. This also indicates that the extent of the cooperativity is essentially smaller than the lowest thickness. Further, contact angle measurement was employed to measure the polymer/substrate interfacial interaction, which was found to be strong (4.09mJ/m2). Consequently, an absorbed layer at the interface and an increase in Tg should be detected. Therefore, further analyses are in progress as an endeavor to quantify the contributions of the interfacial and the free surface layers.