Solid friction between soft filaments.
Any macroscopic deformation of a filamentous bundle is necessarily accompanied by local sliding and/or stretching of the constituent filaments. Yet the nature of the sliding friction between two aligned filaments interacting through multiple contacts remains largely unexplored. Here, by directly measuring the sliding forces between two bundled F-actin filaments, we show that these frictional forces are unexpectedly large, scale logarithmically with sliding velocity as in solid-like friction, and exhibit complex dependence on the filaments' overlap length. We also show that a reduction of the frictional force by orders of magnitude, associated with a transition from solid-like friction to Stokes's drag, can be induced by coating F-actin with polymeric brushes. Furthermore, we observe similar transitions in filamentous microtubules and bacterial flagella. Our findings demonstrate how altering a filament's elasticity, structure and interactions can be used to engineer interfilament friction and thus tune the properties of fibrous composite materials.
Martin Fisher School of Physics, Brandeis University, 415 South Street Waltham, Massachusetts 02454, USA.
Andrew
A
Ward
Martin Fisher School of Physics, Brandeis University, 415 South Street Waltham, Massachusetts 02454, USA.
Feodor
F
Hilitski
Martin Fisher School of Physics, Brandeis University, 415 South Street Waltham, Massachusetts 02454, USA.
Walter
W
Schwenger
Graduate Program in Biophysics and Structural Biology, Brandeis University, 415 South Street Waltham, Massachusetts 02454, USA.
David
D
Welch
Department of Physics, Florida Atlantic University, 777 Glades Road Boca Raton, Florida 33431, USA.
A W C
AW
Lau
Instituut-Lorentz for Theoretical Physics, Universiteit Leiden, 2300 RA Leiden, The Netherlands.
Vincenzo
V
Vitelli
1] School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA [2] Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138, USA.
L
L
Mahadevan
Martin Fisher School of Physics, Brandeis University, 415 South Street Waltham, Massachusetts 02454, USA.
Zvonimir
Z
Dogic
D004548:Elasticity; D017276:Friction; D008962:Models, Theoretical; D011108:Polymers / Q000737:chemistry
D011108:Polymers