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CPP: Chemische Physik und Polymerphysik

CPP 12: Crystallization in Polymers

CPP 12.6: Vortrag

Donnerstag, 5. April 2001, 17:25–17:45, 111

Random Crystallization of Isolated Spheres Confined in a Block Copolymer Mesostructure — •Thomas Thurn-Albrecht¹, Andreas Röttele¹, Günter Reiter², and Jens-Uwe Sommer² — ¹Fakultät für Physik, Universität Freiburg, Germany — ²ICSI, Muhlhouse, France

We report about crystallization in a strongly segregated block copolymer melt containing a short crystallizable and a longer amorphous block, as observed by AFM, x-ray scattering and calorimetry.

The microphase structure of the material (PEO−b−PB_h) consisting of spheres arranged on a cubic lattice remains unchanged by the crystallization process which is confined to the individual spheres. Thin films show a well defined surface structure allowing a reliable observation of the crystallization kinetics and of the melting process by AFM. A comparison with calorimetric measurements sensitive to the bulk signal shows consistent behavior. The experiments directly show that the crystallization proceeds sphere by sphere induced by homogeneous nucleation. Due to the extreme confinement the metastable melt inside the spheres can be locally preserved over a large temperature range.