Viscosity of Flexible and Semiflexible Ring Melts: Molecular Origins and Flow-Induced Segregation

R Datta and F Berressem and F Schmid and A Nikoubashman and P Virnau, MACROMOLECULES, 56, 7247-7255 (2023).

DOI: 10.1021/acs.macromol.3c01046

We investigate with numerical simulations the molecular origin of viscosity in melts of flexible and semiflexible oligomer rings in comparison to the corresponding systems with linear chains. The strong increase of viscosity with ring stiffness is linked to the formation of entangled clusters that dissolve under shear. This shear-induced breakup and alignment of rings in the flow direction lead to pronounced shear- thinning and non-Newtonian behavior. In melts of linear chains, the viscosity can be associated with the (average) number of entanglements between chains, which also dissolve under shear. While blends of flexible and semiflexible rings are mixed at rest, the two species separate under flow. This phenomenon has potential applications in microfluidic devices to segregate ring polymers of similar mass and chemical compositions by their bending rigidity.

Return to Publications page