Dynamics of Complex Fluids Formed by Ionizable Polymers: From Reciprocal Space to Real Space and Back*

The dynamics of complex fluids, particularly of soft matter formed by polymers that consist of segments with inherently different characteristics,  span a broad range of coupled times  and length scale motion from ns to macroscopic times, across length scale that varies from 0.1nm to macroscopic.  This coupling presents a challenge to elucidating the dynamic processes that underlie the properties of these soft systems, driving our journey from reciprocal to real space and back. Using neutron techniques, including  elastic  and quasi elastic scattering , coupled with large scale atomistic and coarse grains molecular dynamics simulations  we were able to attain insight into a long-standing puzzle of how very limited number of ionizable groups tethered to a  polymer backbone  arrest  their macroscopic motion in different complex fluids.   Results for the dynamics of polystyrene  ionizable polymers based complex fluids, including melts, solutions, and micellar phases will be presented, as the complexity of the polymers is increased.    Reciprocal space measurements of SANS, QENS and NSE for polystyrene sulfonate will be first introduces followed  by measurements of complex fluids formed by   co- polymers  that contain a polystyrene sulfonate block.  Moving to real space, results of large-scale molecular dynamics simulations of the same systems will be presented. In conclusion, we will showcase the dynamics derived from the computed complex fluids and illustrate their integration with the reciprocal findings obtained through neutron scattering techniques.