Rod-Coil Block Copolymer Self-Assembly in Thin Films

ORAL

Abstract

The phase behavior of rod-coil block copolymers differs from that of traditional block copolymers due to the interplay between liquid crystallinity of the rod blocks and microphase separation of the rods and coils. A universal phase diagram for rod-coil diblock copolymers is prepared using experimental measurements of both the rod aligning interaction and the rod-coil repulsive interaction to transform the temperature-dependent phase transitions of a model-rod coil system into dimensionless parameter space. The rod aligning interaction, parameterized by the Maier-Saupe parameter, may be estimated from the dependence of the nematic-isotropic transition temperature on the molecular weight of the rod homopolymer. The rod-coil interaction, parameterized by the Flory-Huggins parameter, is calculated from the temperature-dependent interfacial segregation of block copolymer to a rod/coil homopolymer interface. The Flory-Huggins parameter is extracted by using it as a fitting parameter in self-consistent field theory to match simulated block copolymer surface excesses to experimental values.

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Authors

  • B.D. Olsen

    University of California Berkeley

  • Venkat Ganesan

    The University of Texas at Austin, University of Texas-Austin, Department of Chemical Engineering, University of Texas at Austin, University of Texas Austin

  • R.A. Segalman

    UC Berkeley, UC Berkeley and Lawrence Berkeley National Laboratories, University of California Berkeley and Lawrence Berkeley National Lab, University of California, Berkeley, Chem. Eng. UC Berkeley, University of California Berkeley