Polymer Crystallization: Ordered Structures in Complex Systems_

Physics Seminar

Talk by Prof. Jens-Uwe Sommer, Leibniz-Institut für Polymerforschung Dresden

The crystallization of long chain molecules requires two ordering processes which take place simultaneously: Transition of each chain from the randomly coiled state into the partially folded and extended state, and the growth of many chains forming a regular crystalline structure. This leads to complex crystallization and nucleation pathways which usually result in non-equilibrium meta-stable states. I will first discuss some issues of possible equilibrium states of chain crystals [1]. Large scale molecular dynamics simulations are presented which allow to investigate molecular details of single lamellar growth out of an entangled polymer melt. The figure shows a snapshot of single lamellar as obtained in the simulations. Spatial-temporal measures of the state of order are introduced to detect precursor states of crystallizing chains during the crystallization pathway [2]. The local entanglement density during crystal growth is analyzed by primitive path analysis [3].

[1] J.-U. Sommer, Eur. Phys. J. E 19, 413 (2006)

[2] C.-F. Luo and J.-U. Sommer Macromolecules 44, 1523 (2011)

[3] C.-F. Luo and J.-U. Sommer, ACS Macro Lett. in press (2013)

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