Rheology of Active Polymer-like T. Tubifex Worms

Abstract

Of all complex fluids, it is probably the rheology of polymers we understand best. In-depth insight into the entanglement and reptation of individual polymers allows us to predict for instance the shear-thinning rheology and the behaviour in virtually any flow situation of practical importance. The situation is markedly different when we move from passive to active polymers where the coupling of filament activity, hydrodynamic interactions, and conformations open the way to a plethora of novel structural and dynamical features. Here we experimentally study the rheology of long, slender and entangled living worms (Tubifex tubifex) and propose this system as a new type of active polymer. Its level of activity can be controlled by changing the temperature or by adding small amounts of alcohol to make the worms temporarily inactive. We find that (i) shear thinning is reduced by activity, (ii) the characteristic shear rate for the onset of shear-thinning is given by the time scale of the activity, and (iii) the low shear viscosity as a function of concentration shows a very different scaling from that of regular polymers. Our study paves the way towards a new research field of `living polymers'.

3,5 pages and 3 figures

References in corpus (6)

• Turning bacteria suspensions into a "superfluid"
• Shear thickening of cornstarch suspensions as a re-entrant jamming transition
• Fluctuations and Rheology in Active Bacterial Suspensions
• Sheared active fluids: thickening, thinning and vanishing viscosity
• Dynamics of active filaments in porous media
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Cited by in corpus (14)

• The physics of active polymers and filaments
• A Geometric Criterion for the Optimal Spreading of Active Polymers in Porous Media
• Phase Separation by Entanglement of Active Polymerlike Worms
• Effects of inertia on conformation and dynamics of tangentially-driven active filaments
• Locomotion of Active Polymerlike Worms in Porous Media
• Simulating active agents under confinement with Dissipative Particles (hydro)Dynamics
• Characteristic features of self-avoiding active Brownian polymers under linear shear flow
• Density and inertia effects on two-dimensional active semiflexible filament suspensions
• Collective action and entanglement of magnetically active liquid crystal elastomer ribbons
• Active Polymer Behavior in Two Dimensions: A Comparative Analysis of Tangential and Push-Pull Models
• Tangentially Active Polymers in Cylindrical Channels
• Activity-enhanced shear thinning of flexible linear polar polymers
• Dynamical Boundary Following and Corner Trapping of Undulating Worms
• Two-dimensional active polar semiflexible polymer under shear flow