Berlin 2012 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 8: Glasses I (with CPP, talks by CPP)

DY 8.8: Vortrag

Montag, 26. März 2012, 17:15–17:30, C 243

Molecular Mobility and Glass Transition of Thin Poly(Bisphenol A Carbonate) Films — •Huajie Yin and Andreas Schönhals — BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany

Glass transition behavior of thin poly(bisphenol A carbonate) (PBAC) films (down to 10 nm) was investigated using capacitive dilatometry (CD), broadband dielectric spectroscopy (BDS) and differential ac-chip calorimeter (DACC) accompanied by contact angle measurements. In the BDS measurements of the thin PBAC films capped between two Al layers, no thickness dependence of the segmental dynamics was detected down to a critical thickness of 20 nm. For thickness below 20 nm, an increase of the relaxation time at a fixed temperature was observed. The thickness dependence of the thermal glass transition temperature determined by CD is in agreement with BDS results. Dynamic glass transition temperature of the ultra-thin PBAC films (10-55 nm) supported on SiO2 layer, with one free surface, was studied by means of differential ac-chip calorimeter as well. No thickness dependence of the dynamic glass transition temperature was observed within an uncertainty of +/-3 K for each frequency. These experimental results are discussed in terms of the different interactions of polycarbonate segments with the different substrates and/or different preparation conditions.