Dipolar interactions as the origin of excess scattering in concentrated solutions and melts of ionic polymers

Scattering is one of the most powerful characterization tools for probing structure and dynamics of polymers at different length and time scales. While the protocols for interpretting scattering from neutral polymers are fairly well-established, interpreting scattering of ionic polymers still pose a great challenge desipte decades of research. In this talk, we will present a generalized theory for studying static structure factor in concentrated solutions and melts of dipolar and ionic polymers. The theory captures the effects of electrostatic fluctuations on the structure factor and provides insights into the origin of excess scattering at ultralow wavevectors in salt-free ionic polymers. The excess scattering can originate from the dipolar interactions resulting from counterion adsorption on the polymers, which leads to screened charge-charge interactions mediated by non-local dielectric media. Also, it will be shown that the structure factor for dipolar polymers can exhibit a peak at a finite wavevector and excess scattering at ultralow wavevectors.