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CPP: Chemische Physik und Polymerphysik

CPP 14: SYMPOSIUM: Understanding and Controlling Complex Structures: From Synthetic Polymers to Biomaterials II

CPP 14.1: Hauptvortrag

Dienstag, 9. März 2004, 14:00–14:30, H 37

Competition of order in liquid crystalline/isotropic block copolymers — •Bernd Stühn¹, Wolfram Gronski², Rosina Staneva¹, Sergei Zhukov¹, and Steffen Geppert² — ¹Technische Universität Darmstadt, Physics of Condensed Matter, D-64289 Darmstadt — ²Albert Ludwigs Universität Freiburg, Institute of Macromolecular Chemistry, D-79104 Freiburg

The formation of structure in block copolymers consisting of an isotropic and a liquid crystalline block is governed by two factors. One is the domain ordering caused by the strong repulsive interaction between both blocks. As a second factor the orientational order of the mesogens in the liquid crystalline block is to be considered.

We have investigated a series of di- and triblock copolymers with the liquid crystalline block either confined within spherical, cylindrical or lamellar domains or forming the continuous matrix. Small and wide angle X-ray scattering has been applied to study structure on a wide range of length scales. The dependence of domain order on the orientational order is studied by variation of temperature and crossing the transition temperature of the liquid crystalline phase. The nematic order of the LC clearly favours the cylindrical over the spherical domain form thus causing a variation of structure with temperature at the LC phase transition. For one example we find a order-to-order transition in the domain structure triggered by the nematic-isotropic phase transition of the liquid crystalline matrix.