Regensburg 2010 – scientific programme
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DS: Fachverband Dünne Schichten
DS 38: Layer Properties: Electrical, Optical and Mechanical Properties
DS 38.4: Talk
Thursday, March 25, 2010, 14:45–15:00, H8
Investigation of structural and mechanical properties of pulsed laser deposited PMMA films — •Felix Schlenkrich1, Britta Lena Fuchs1, Peter Großmann2, Klaus Mann2, and Hans-Ulrich Krebs1 — 1Institut für Materialphysik, Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen — 2Laser-Laboratorium Göttingen e.V., Hans-Adolf-Krebs-Weg 1, D-37077 Göttingen
Smooth poly(methyl methacrylate) (PMMA) films without any droplets were pulsed laser deposited at a wavelength of 248 nm and a laser fluence of 125 mJ cm−2. After deposition at room temperature the films obey a low universal hardness of only 3 N mm−2. Thermal treatments up to 200∘C, either during deposition or afterwards lead to a film hardening up to values of 200 N mm−2.
Using a combination of complementary methods, two main mechanisms could be made responsible for this temperature induced hardening effect well above the glass transition temperature of 200∘C.
The first process is induced by the evaporation of chain fragments and low molecular mass material, which are present in the film due to the deposition process, leading to an increase of the average molecular mass and thus to hardening. The second mechanism can be seen in the cross-linking of the polymer film as soon as chain scission occurs at higher temperatures and the mobility and reactivity of the polymer material is high enough.