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IRTG / Soft Matter Science
Freiburger Materialforschungszentrum
Stefan-Meier-Str. 21
79104 Freiburg, Germany


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You are here: Home Events Prof. Bernard Lotz "The structure of crystalline polymers: contributions of electron microscopy and AFM. "

Prof. Bernard Lotz "The structure of crystalline polymers: contributions of electron microscopy and AFM. "

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Institut Charles Sadron, Strasbourg, France

  • Seminar
When Jun 20, 2012
from 02:15 PM to 03:15 PM
Where Hörsaal Makromolekulare Chemie, Stefan-Meier-Str. 31, Freiburg
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Crystalline polymers are made of small (several micrometers) and thin (one to several tens of nanometers) lamellae, which amounts to ≈10-12 grams of material. Electron microscopy is therefore an ideal tool for their investigation, in spite of the high susceptibility of polymers to electron beam damage.

The use of single crystals produced in thin films or solution, as well as epitaxially crystallized materials yields unusual structural and morphological details on the crystalline core and the fold structure. These simple morphologies provide essential clues to analyze more complex lamellar morphologies observed in spherulites.

Even though detailed information is frequently available, the molecular analysis (or even better, sometimes, the sub-molecular analysis) remains difficult. Several "classical" structural problems have remained unsolved for decades! To overcome such difficulties, gathering and combining information provided by different polymers may become essential.

The presentation is intended to be very didactic. Among others, it will illustrate (a) the use of dark field imaging to visualize and investigate crystal-crystal transformations (b) the combined use of epitaxial crystallization, electron diffraction and AFM to observe the structure of polymers with methyl group resolution (≈4Å) (c) the concept of frustrated packing in crystalline polymers  (d) the investigation of the fold structure and associated surface stresses that induce twisted and scrolled lamellar morphologies.


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