Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 31: Thin Films
CPP 31.6: Vortrag
Donnerstag, 28. Februar 2008, 10:45–11:00, C 264
Glass transition and miscibility of polymer blends in ultra-thin films — •Dongshan Zhou1,2, Heiko Huth1, Alexander Minakov1, and Christoph Schick1 — 1Inst. Phys., Univ. Rostock, Germany — 2School. Chem. & Chemical Eng., Nanjing Univ., China
Glass transition and polymer blend miscibility in ultra-thin films is critical for their use as materials. Calorimetric studies can provide important information on finite size and interfacial effects on the phase separation. Here we use the recently developed differential alternating current chip calorimeter to study glass transition and miscibility of blend composed of equal mass ratio of polystyrene and poly(2,6-dimethyl-p-phenylene oxide)confined in thin film (5 ~ 320 nm). The step of heat capacity during the glass transition is well indentified even for the thinest film of c.a. 4.5 nm, showing the performance of the calorimeter to measure the change of heat capacitity in the level of picoJ/K[H. Huth, J. Polym. Sci. B Polym. Phys. 2006, 44, 2996]. Despite the remarkable change of thickness (from below 1/2 Rg to 13.5 Rg), both the glass transition temperature and the temperature range of the transition keep unchanged in the frequency range available. The independence of the Tg with thickness in this work is in consistence with calorimetric measurements in thin films of single component polymers, but contrary to previous work on the same polymer blends based on ellipsometry [J. H. Kim, Macromolecules, 2002, 35,311]. In the system under investigation we see only one glass transition, arguments on whether the miscibility is changed or not due to the confinement will be available after investigation on a wider range of compositions.