Rod-to-Coil Transition in Polypeptide/$\pi$-Conjugated Polymer/Polypeptide Triblock Copolymers

ORAL

Abstract

Self-assembly in the bulk of a series of hybrid triblock copolymers formed by a poly(9,9-dihexylfluorene-2,7-diyl) (PHF) internal block and two poly($\gamma $-benzyl-L-glutamate) (PBLG) external blocks has been studied. Since the $\alpha $-helical secondary structure of the PBLG block may be either maintained or suppressed depending on the solvent casting history, the PBLG-PHF-PBLG copolymers exhibit two different conformations: a rod-rod-rod or coil-rod-coil configuration, respectively. To provide insight on the influence of molecular architecture on self-aggregation of these systems, three copolymers with different block ratio were investigated in both conformations using small- and wide-angle scattering techniques and transmission electron microscopy. Time-resolve photoluminescence measurements were performed on the same samples to explore the effect of morphology on photophysical properties. The observed photoluminescence spectra and dominant excited lifetimes of the poly(9,9-dihexylfluorene-2,7-diyl) block were found to differ markedly in rod-rod-rod and coil-rod-coil configurations and were correlated to the morphology of the self-assembled triblock copolymers.

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Authors

  • Raffaele Mezzenga

    • Fribourg University, Physics Department, Switzerland
    • University of Fribourg, Physics Department

  • Laurent Rubatat

    • Fribourg University, Physics Department, Switzerland

  • Xiangxing Kong

    • University of Washington, Seattle, USA

  • Samson Jenekhe

    • University of Washington, Seattle, USA

  • Janne Ruokolainen

    • Helsinki University of Technology, Finland

  • Mohamad Hojeij

    • EPFL, Switzerland