Dialkyl- and Dialkoxy-functionalized Poly(thieno(3,4-b)pyrazine)s via GRIM Polymerization: Side Chain Tuning of Electronic and Optical Properties

Thieno[3,4-b]pyrazine homopolymers were prepared via GRIM polymerization methods and characterized to illustrate the ability to tune these materials by selection of the solubilizing side chains. All of the generated poly(thieno[3,4-b]pyrazine)s exhibited low band gaps (0.95-1.13 eV), with both the band gap and frontier orbitals dependent on the choice of side chain. The effect of side chain length on polymer molecular weight was also investigated. Analysis of the resulting polymer properties reveal clear trends in which the material's band gap increased with the use of either longer alkyl or more electron-donating alkoxy side chains.