Soluble Conjugated Polymers without Side Chains: Macrocycles as Comonomers

Solubility and processability play critical roles in the practical application of conjugated polymers, in addition to their optoelectronic properties. Enhancing these features is normally accomplished by attaching aliphatic side chains to the polymer backbone, which, however, can come at the expense of other desirable properties, such as charge carrier mobility and crystallinity. Here, we present a promising alternative approach: incorporating conjugated macrocycles into the conjugated polymer backbone. To demonstrate this approach, we synthesized two novel macrocycle-containing polymers, poly(PCT-T) and poly(PCT-2T), which we found to be soluble in chloroform despite not featuring any aliphatic side chains. The polymers displayed minimal structural defects as well as high conformational flexibility and a tendency towards linearity, as confirmed by electrospray deposition scanning tunneling microscopy, and promising photophysical and electrochemical properties, with computational modeling confirming retained macrocycle functionality. The presented approach unlocks a new avenue for the design of solution-processable conjugated polymers with enhanced performance in organic battery electrodes and (opto)electronic devices.