Internal friction in polyelectrolytes

E. Buvalaia, M. Kruteva, I. Hoffmann, A. Radulescu, S. Förster, R. Biehl

Polyelectrolytes (PE) are charged polymeric macromolecules in aqueous solution (see Fig. 1) which have a wide application range as thickeners, emulsifiers, drag reduces or clarifying agents. In a multiscale approach combining different methods as dynamic light scattering, neutron spinecho spectroscopy, small angle neutron scattering and pulse field gradient NMR chain dynamics was explored.

The chainlike macromolecule expands at low salt concentration because of the charges, but high salt screens the charges and the macromolecule shrink.  Surprisingly the segment dynamics is always that of a neutral polymer chain with friction between neighbouring segments.

Internal friction in polyelectrolytes
Figure 1: Effective diffusion Deff for PSSH (dots). The Zimm model of a neutral chain (dashed + low Q red line) describes segment dynamics. Internal friction slows down segment dynamics at larger Q (green area) because of friction between neighbouring monomers (right illustration). Interchain interactions (left illustration) increase Deff at low Q showing collective chain diffusion (black line).
Copyright:
— Ralf Biehl, JCNS-1 / Forschungszentrum Jülich CC-BY 4.0

[1] E. Buvalaia et al., Interchain Hydrodynamic Interaction and Internal Friction of Polyelectrolytes,
ACS Macro Lett 22, 1218 (2023)  DOI: 10.1021/ACSMACROLETT.3C00409.

Last Modified: 26.04.2024