Title: Tuning the optoelectronic properties of P3EHT block copolymers by surface modification

Authors: Lisa T. Strover; Bryan McCulloch; Victor Ho; Rachel Segalman; Jenny Malmström; Duncan J. McGillivray; Jadranka Travas-Sejdic

Addresses: School of Chemical Sciences, The University of Auckland, Auckland, 1010, New Zealand; The MacDiarmid Institute, Wellington, 6012, New Zealand ' Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, USA ' Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, USA ' Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, USA ' School of Chemical Sciences, The University of Auckland, Auckland, 1010, New Zealand; Department of Chemical and Materials Engineering, The University of Auckland, Auckland, 1010, New Zealand ' School of Chemical Sciences, The University of Auckland, Auckland, 1010, New Zealand; The MacDiarmid Institute, Wellington, 6012, New Zealand ' School of Chemical Sciences, The University of Auckland, Auckland, 1010, New Zealand; The MacDiarmid Institute, Wellington, 6012, New Zealand

Abstract: P3AT-containing block copolymers (BCPs) have potential for use as electroactive polymer brushes for stimuli-responsive surfaces, with reversible tethering of the P3AT block. This kind of tethering is highly dependent on the P3AT block's affinity for the surface. We have investigated the effect of surface modification on P3EHT-b-PS and P3EHT-b-PtBA films deposited on ITO-coated glass substrates modified by electrodeposition of poly(terthiophene). Optical and electrochemical properties of the BCPs deposited both on PTTh films and on bare ITO were investigated by UV-Vis spectroscopy and cyclic voltammetry, respectively. These characterisations reveal interplay between deposition conditions and the optoelectronic behaviour of BCPs investigated, and also provide insight as to their morphology under various conditions as it impacts on such behaviour. Significantly, electrochemically-driven switches in the morphology of BCPs were observed, however polymer-solvent interactions dominated. Absorbance spectra revealed a strong interaction between BCPs and the poly(terthiophene) substrates, manifesting as disruptions in crystallinity in the BCPs.

Keywords: rod-coil BCPs; block copolymers; poly(thiophene) substrates; cyclic voltammetry; self-assembly; surface chemistry; P3ATs; optoelectronic properties; electroactive polymer brushes; stimuli-responsive surfaces; conducting polymers; thin films; surface modification; reversible tethering; morphology.

DOI: 10.1504/IJNT.2017.082481

International Journal of Nanotechnology, 2017 Vol.14 No.1/2/3/4/5/6, pp.540 - 557

Published online: 21 Feb 2017 *

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