Nanoscale organization in thin films of regioregular poly(3-hexylthiophene) block copolymers

PMSE 2

Rui Zhang, ruizhang@andrew.cmu.edu1, Mihaela C. Iovu1, Geneviève Sauvé1, Jessica R. Cooper1, Anna E. Javier, ajavier@cmu.edu1, Detlef M. Smilgies2, Richard D. McCullough, rm5g@andrew.cmu.edu3, and Tomasz Kowalewski, tomek@andrew.cmu.edu1. (1) Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, (2) Cornell High Energy Synchrotron Source, Cornell University, Cornell University, CHESS, Ithaca, NY 14850, (3) Dean, Mellon College of Science, Carnegie Mellon University, 4400 Fifth Ave., Pittsburgh, PA 15213
Regioregular poly(3-alkylthiophene)s (RR-P3ATs) stand out among the most promising conjugated polymers, owing to their superior charge carrier mobilities. The performance of conjugated polymer based devices is determined primarily by the chemical structure, supramolecular structure/organization and thin film morphology. Therefore, the control of supramolecular structures is one of the key elements in the optimization of devices based on these materials. One of the new approaches here involves the synthesis of block copolymers comprised of rigid conjugated polymer building blocks linked to flexible blocks with which they are immiscible. Using controlled radical polymerization techniques, we have successfully achieved diblock and triblock RR-P3HT copolymers with a variety of flexible blocks. Herein we focus on the peculiarities of supramolecular structure and organization of these block copolymers. Combined atomic force microscopy and grazing incidence small angle x-ray scattering studies revealed that over the wide range of compositons, block copolymers containing RRP3HT tend to form characteristic nanofibrillar morphologies resembling those observed in the RR-P3HT homopolymers. This remarkable insensitivity of morphology to the volume fraction of the RR-P3HT segment is in sharp contrast to the flexible coil-coil systems. It is a strong indication that the self assembly of RR-P3HT copolymers is dominated by the aggregation of conjugated polymer segments. Further elucidation of the interplay of this process with the phase separation from the second block will be critical for optimal utilization of these new materials in devices.
 

New Concepts in Polymeric Materials
8:00 AM-11:20 AM, Sunday, August 19, 2007 Westin Boston Waterfront -- Grand Ballroom D, Oral

Division of Polymeric Materials: Science & Engineering

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007