How does PEDOT combine with PSS? Insights from structural studies

The severely intractable polymer poly(3,4-ethylenediethoxythiophene) (PEDOT) is brought to stable aqueous solution after in situ combination with polystyrene sulfonic acid (PSS). This solution (PEDOT-PSS) is stable and successfully combines the optical and electrical properties of PEDOT with the water solubility of PSS. This paper explores the physical properties of PEDOT-PSS from morphological and structural aspects and electronic structure studies are employed to understand the interaction between the two polymers. The solution consists of triangular/rectangular shaped nanoparticles and UV-vis spectroscopy is used to establish the highly doped and conductive nature of the sample with bipolarons present as carrier. Theoretical studies reveal the structure of the interpolymer complex and that the PEDOT chain is bent towards the PSS moiety, and thus, PEDOT-PSS is likely to form a partially coiled or helical structure. The unique stability of this system as well as its highly conductive nature is also consistent with the molecular model.