Alterations in Conformations of Poly(3-Hexylthiophene) on Au(111) Induced by Annealing

Abstract

Employing high-vacuum electrospray deposition and scanning tunneling microscopy, we investigated how individual poly(3-hexylthiophene) (P3HT) chains navigated on the periodic energy landscape of the herringbone pattern of a reconstructed Au(111) surface. The resulting polymer conformations were governed by the interplay of corrugated substrate and thermal energy. On a regularly reconstructed surface, annealing at 100 °C provided sufficient energy for chain segments to overcome surface energy barriers. As a result, the adsorbed polymers preferred conformations that replicated the herringbone pattern. By contrast, on an irregularly reconstructed surface, a diverse mix of coiled polymer chains performing a two-dimensional random walk and collapsed chains was observed. Intriguingly, annealing at 200 °C forced polymers to form clusters of many chains. Our results establish that thermal energy and substrate topography represent control parameters for altering polymer conformations, providing a framework for rationally designing polymer nanostructures at the molecular level.