Multiscale study of the effects of the solvent treatment of conductive PSS:PEDOT polymer

Dimethyl sulfoxide (DMSO) and ethylene glycol (EG) solvent treatment of conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were studied using multiscale analysis and dissipative particle dynamic (DPD) simulations. The DPD inter particle repulsion parameters and intramolecular bonding parameters were obtained by reverse mapping of a series of molecular dynamic simulations similar to that used in the earlier contributions. The solvent treatments were found to cause three effects on PEDOT polymer chains at molecular level, increasing rigidity in monomer-monomer bending, decreasing rigidity in monomer-monomer stretching, and decreasing repulsion among monomers. Consequently, these effects lead to PEDOT micro phase segregation and semi-ordered local region formation within and/or between polymer chains. Since the reduction of repulsion among PEDOT monomers can only be caused from selective π−π staking, the formation of these semi-ordered (crystal like) local region may allow charges to bypass local disordered region within the polymer chain and hopping between individual polymer chains, thus, enhance electrical conductivity in orders of magnitude. The implication on PSS:PEDOT:PFI are discussed.