Regensburg 2004 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 15: POSTER: Polymers and Biomaterials

CPP 15.30: Poster

Dienstag, 9. März 2004, 17:00–19:00, B

Orientation of the Microdomains in Concentrated Block Copolymer Solutions using Electric Fields: Confinement Effects and Mechanisms — •Kristin Schmidt¹, Helmut Hänsel¹, Frank Schubert¹, Heiko Zettl¹, Thomas Weiss², Franz Fischer³, Volker Abetz⁴, Alexander Böker^1,5, and Georg Krausch¹ — ¹Physikalische Chemie II, Universität Bayreuth, Bayreuth, Germany — ²ESRF, Grenoble, France — ³Kristallographie, Universität Bayreuth, Bayreuth, Germany — ⁴Makromolekulare Chemie II, Universität Bayreuth, Bayreuth, Germany — ⁵Department of Polymer Science & Engineering, University of Massachusetts, Amherst, USA

We investigate the microdomain orientation of concentrated block copolymer solutions exposed to a DC electric field by time-resolved synchrotron SAXS. As a model system, we use a lamellar polystyrene-b-polyisoprene block copolymer dissolved in toluene. Depending on the polymer concentration we can identify two different microscopic mechanisms which dominate the orientation process, i.e. nucleation and growth of domains and grain rotation. The former dominates close to the ODT, while the latter prevails under more strongly segregated conditions.

Reduction of the electrode spacing from 2mm to 200µm leads to a dramatic increase in the time constant of the orientation process, i.e. it is slowed down significantly. This finding is attributed to a confinement effect which finally results in complete trapping of the process. Furthermore, in the case of highly segregated samples we observe that increasing confinement suppresses the grain rotation mechanism, favoring nucleation and growth for highly confined systems.