Synthesis, optical and electrochemical properties of thiophene and thieno [3, 2-b] thiophene linked with structurally modified rhodanine based copolymers

• Design and synthesis of thiophene and thieno [3, 2-b] thiophene linked with conjugated side chains of 3-octylrhodanine based D-A polymer. • Structural, optical, electrochemical and thermal properties was studied. • Electronic energy levels investigated by DFT method. • Influence of side chain was examined. Thiophene and thieno [3, 2-b] thiophene as an electron rich donor linked with conjugated side chains of 3-octylrhodanine as an acceptor was designed, polymerized via Stille polycondensation route and two copolymers, PTMOT-T (P1) and PTMOT-TT (P2) was obtained. Polymers was completely characterized by different sophisticated instruments (FT-IR, 1 HNMR, TGA, GPC, XRD and DFT simulations). Presence of 3-octylrhodanine side chain units was influences the solubility, conformations and electronic properties of resulted polymers. Polymers displayed broad optical absorption, compatible molecular orbitals HOMO and LUMO levels and good thermal stability. Structural features and influence of side chain in PTMOT-T (P1) and PTMOT-TT (P2) was discussed and it could be potential materials for optoelectronic applications. This work showed that the slight modification side chain structure and or side chain engineering is plays a crucial role to tune the structural and optoelectronic properties of desired polymers.