Anodic Chlorination of Poly(3-(2-ethylhexyl)Thiophene) Films Facilitated by Constructing Ordered Structures

Abstract

π-Conjugated polymer (CP) is known to show unique optoelectronic properties due to their extended π-conjugation moieties along with their main chains.[1] To control these properties, post-functionalization methods are powerful approaches. Among post-functionalization methods, electrochemical post-functionalization (ePF) is a useful and promising approach to manipulate the optoelectronic properties of the film-state CPs.[2] Considering their optoelectronic properties in the film state, these properties are often affected by their structures. On the basis of this idea, the structure of CP films is expected to serve a crucial role in the efficacy of ePF; however, the relationship between their structures and ePF methods remains unexplored.In this work, we report the relationship between the structures of CP films and the efficacy of ePF by performing anodic chlorination of poly(3-(2-ethylhexyl)thiophene) (P3EHT) films (Figure 1).[3] Changing solvents used in preparing P3EHT films is found to result in P3EHT films with different structures (i.e., amorphous and crystalline structures). The amorphous P3EHT films are not electrochemically chlorinated, whereas P3EHT films possessing crystalline domains are successfully chlorinated in the same reaction conditions. In situ conductance measurements of P3EHT films evidence that the reactivity difference in the anodic chlorination between both P3EHT films is because of their electrical conductivity.