Electric Field Orientation of Poly(p-styrenesulfonate) and Its 9-Aminoacridinium Complex as Studied by Square-pulse Transient Electric Birefringence

Abstract

Abstract Electric birefringence was measured at 20 °C and at 535 nm for sodium poly(p-styrenesulfonate) (NaPSS), with and without added sodium chloride, and the 9-aminoacridinium (AA) complex in aqueous solutions. The field strength dependence of both the steady-state EB (Δn(∞)) the field-free decay time (〈τ〉EB) was examined. Charge suppression by added Na+ ions or neutralization by strongly bound AA decreased both Δn(∞) and 〈τ〉EB considerably, altering not only the optical factor Δg and electric moments, but also the backbone chain length. The weight-average values of chain length (lw), pseudopermanent dipole moment (μw), counterion-induced electric polarizability anisotropy (Δαw), and the length-independent values of Δg were estimated by analyzing the experimental data on the basis of the “classical” orientation function which takes into account the continuous distribution of chain length for the polydisperse NaPSS sample. The electric field orientation of NaPSS and the AA-complex could be described by the interaction between an applied field and the electric moment which transforms from counterion-induced type in the extremely low field region (<1.5 kV/cm) to saturated induced permanent type at higher fields.