Regioregular improvement on the oxidative polymerization of poly‐3‐octylthiophenes by slow addition of oxidant at low temperature

Abstract

Many pathways can be used to synthesize polythiophenes derivatives. The polycondensation reactions performed with organometallics are preferred since they lead to regioregular polymers (with high content of heat-to-tail coupling) which have enhanced conductivity and luminescence. However, these pathways have several steps; the reactants are highly moisture sensitive and expensive. On the other hand, the oxidative polymerization using FeCl 3 is a one-pot reaction that requires less moisture sensitive reactants with lower cost, although the most common reaction conditions lead to polymers with low regioregularity. Here, we report that by changing the reaction conditions, such as FeCl 3 addition rate and reaction temperature, poly-3-octylthiophenes with different the regioregularities can be obtained, reaching about 80% of heat-to-tail coupling. Different molar mass distributions and polydispersivities were obtained. The preliminary results suggest that the oxidative polymerization process could be improved to yield polythiophenes with higher regioregularity degree and narrower molar mass distributions by just setting some reaction conditions. We also verified that it is possible to solvent extract part of the lower regioregular fraction of the polymer further improving the regioregularity degree.

Synthesis of ferrocene-based polythiophenes and their applications

“…Although the synthesized polymers via this kind of polymerization have low regioregularity and a high polydispersity index, this polymerization is very easy to carry out, the reagents are very cheap, and the reaction is less sensitive to moisture and can be performed in one step. 32 The degree of polymerization and the molecular weight of the polymer can be controlled to a certain extent by the oxidant ratio and/or the reaction time. The molecular weight of the polymer is directly proportional to the quantity of oxidant and the reaction time.…”

“…Because this is an oxidative polymerization, initiation and propagation are dependent on the availability of the oxidant; i.e., the higher the quantity of oxidant, the longer will be the chain length. 32,[37][38][39] Using a simple oxidative polymerization, a water-soluble polymer 9 was synthesized (Scheme 4) and it was further used in important applications. In addition to the ferrocene, a cationic group was also present in the side group, which was responsible for the solubility of the polymer in water.…”

“…Following the Suzuki polycondensation, 2,5′-dibromobithiophene and 1,1′-bis( p-bromophenyl)-ferrocene were copolymer-Scheme 3 Mechanism of different possible initiation routes and chain propagation for oxidative polymerization. 32 Scheme 4 Examples of oxidative polymerizations. 22,23,[40][41][42] ized with 9,9-dihexylfluorene-2,7-diboronic acid (14, Scheme 6).…”

Electrochemical polymerization of 2‐thiophen‐3‐yl‐malonic acid for biosensor application

“…Among which, polythiophene is regarded as one of the most technologically promising conducting polymer because of its easy of preparation, low cost, high environment and thermal stability, relatively stable electrical conductivity and its special properties 6–8. As an illustration, polythiophene and its derivatives do not easily suffer ring opening reactions when compared to polyfurans and polypyrrols 9. Highly π‐conjugated polythiophene has been composed by the electrochemical method.…”