Self-Assembly of Polypeptide/π-Conjugated Polymer/Polypeptide Triblock Copolymers in Rod−Rod−Rod and Coil−Rod−Coil Conformations

• Published in: Macromolecules 2008-03, Vol.41 (5), p.1846-1852
• Main Authors: Rubatat, Laurent, Kong, Xiangxing, Jenekhe, Samson A, Ruokolainen, Janne, Hojeij, Mohamad, Mezzenga, Raffaele
• Format: Article
• Language: English
• Subjects: Aminoacid polymers; Applied sciences; Exact sciences and technology; Physicochemistry of polymers; Physics; Synthetic biopolymers
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma702278a

Self-assembly in the bulk of a series of hybrid triblock copolymers formed by a poly(9,9-dihexylfluorene-2,7-diyl) (PHF) middle block and two poly(γ-benzyl-l-glutamate) (PBLG) end blocks has been studied. Since the α-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. In order to provide insight into the influence of conformation 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-resolved 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.