Single flexible and semiflexible polymers at high shear: Non-monotonic and non-universal stretching response

Abstract

Using Brownian hydrodynamic simulation techniques, we study single polymers in shear. We investigate the effects of hydrodynamic interactions, excluded volume, chain extensibility, chain length and semiflexibility. The well-known stretching behavior with increasing shear rate [Formula: see text] is only observed for low shear [Formula: see text] < [Formula: see text] , where [Formula: see text] is the shear rate at maximum polymer extension. For intermediate shear rates [Formula: see text] < [Formula: see text] < [Formula: see text] the radius of gyration decreases with increasing shear with minimum chain extension at [Formula: see text] . For even higher shear [Formula: see text] < [Formula: see text] the chain exhibits again shear stretching. This non-monotonic stretching behavior is obtained in the presence of excluded-volume and hydrodynamic interactions for sufficiently long and inextensible flexible polymers, while it is completely absent for Gaussian extensible chains. We establish the heuristic scaling laws [Formula: see text] approximately N (-1.4) and [Formula: see text] approximately N (0.7) as a function of chain length N , which implies that the regime of shear-induced chain compression widens with increasing chain length. These scaling laws also imply that the chain response at high shear rates is not a universal function of the Weissenberg number Wi = [Formula: see text] [Formula: see text] anymore, where [Formula: see text] is the equilibrium relaxation time. For semiflexible polymers a similar non-monotonic stretching response is obtained. By extrapolating the simulation results to lengths corresponding to experimentally studied DNA molecules, we find that the shear rate [Formula: see text] to reach the compression regime is experimentally realizable.

Shear-induced dynamics of polymeric globules at adsorbing homogeneous and inhomogeneous surfaces

“…1b. The transition between isotropic and prolate conformations (orange line) extends into the coil state and separates the slipping isotropic coil state SC from the slipping prolate coil state SPC, in agreement with previous observations [13,33]. In fig.…”

Influence of shear on globule formation in dilute solutions of flexible polymers

“…63 It also indicates that decrease in polymer size observed in this article is not related to ultra-high shear rate (Wi > N 2 K ) compaction of the polymer chain studied by Sendner and Netz, 67 and later elucidated by Dalal et al 66 Further evidence pointing to attachment of colloids in stretched polymers leading to globule formation by the mechanism described above is that the MFPT is inversely proportional to colloid concentration as shown in the supplementary material. 63 The breakup of globules in shear flow has received much attention recently due to its importance in biology and in determining properties of gels.…”

Effects of excluded volume and hydrodynamic interaction on the deformation, orientation and motion of ring polymers in shear flow

“…1,2 The influence of EV on the behaviors of polymer chains in shear flow is a subject of great interest including the fundamental understanding of solvent quality, 1 and novel technological applications for polymer separation and purification. [14][15][16][17][18][19][20][21] Experimentally, Muller et al observed that linear polymers have larger stretching and weaker orientation in good solvents than in theta solvents based on a light scattering study of in situ flow. [14][15][16][17][18][19][20][21] Experimentally, Muller et al observed that linear polymers have larger stretching and weaker orientation in good solvents than in theta solvents based on a light scattering study of in situ flow.…”

“…1,2 The HI makes buried or exposed polymer monomers feel different solvent drag. 17,19,[31][32][33] Sendner and Netz found that the dominant HI, which screens interior monomers from hydrodynamic drag, can reduce the stretching of linear chains under shear. In the fully extended conformation, more monomers are exposed to the flow, and the effects of HI are diminished.…”