Design, Synthesis, Characterization, and Modeling of a Series of S,S-Dioxothienylenevinylene-Based Conjugated Polymers with Evolving Frontier Orbitals

A series of evolving frontier energy levels and gaps sulfone-containing thienylenevinylene-based conjugated copolymers have been synthesized via the Horner−Emmons reactions between 2,5-bisdiethoxyphosphorylmethyl-3,4-dihexyl-1,1-dioxothiophene and a series of different donor type dialdehyde comonomers. The resulting polymers (SF-PTVs) contain alternating donor (benzene or thiophene ring with/without alkoxy substituents) and acceptor (1,1-dioxothiophene) units. A range of HOMO/LUMO levels and energy gaps (between 1.0 and 2.0 eV) were achieved in these new polymers. The use of oxidized thiophene moiety brings about 0.3 eV in reduction of energy gap. Computational study on the model oligomers of P(C6OTV-SFTV) and related structures reveals that the reduction is mainly due to the removal of aromaticity of the thiophene. The donor−acceptor interaction is also responsible for about one-third or less of the energy gap reduction. Theses polymers have very good thermal stability (dynamically, 258 °C or higher), and their decomposition starts with loss of mass as in contrast to regular PTVs which decompose initially by cross-linking.