Self assembling of Poly(3-hexylthiophene) (P3HT)

TL;DR

This study combines computational methods to investigate how P3HT chains self-assemble, revealing the dominant role of pi-pi interactions and the influence of external constraints on resulting structures.

Contribution

It provides new insights into the molecular mechanisms of P3HT assembly and how external factors can alter the resulting polymer morphology.

Findings

pi-pi interactions drive assembly in absence of constraints

single chains form 2D hydrophobic foils

external constraints can lead to aligned thiophene structures

Abstract

We study the assembling of P3HT chains in vacuo by means of a combination of first principles density functional theory and model potential molecular dynamics. We find that, in the absence of any external constraints, the pi-pi interchain interaction between thiophenes is the major driving force for the assembling. Single chains stack in a staggered geometry giving rise to the formation of two-dimensional hydrophobic foils. These, in turn, assemble into a zigzag bulk polymer structure in agreement with experimental findings. Finally, in the presence of some external constraint (like e.g. a substrate), when the alignment of single chains is favored instead of the stacking, a different bulk structure is possible where thiophene rings are aligned.