Visualizing the Strain Field in Semiflexible Polymer Networks: Strain Fluctuations and Nonlinear Rheology ofF-Actin Gels

Visualizing the strain field in semiflexible polymer networks: strain fluctuations and nonlinear rheology of F-actin gels.

We image semiflexible polymer networks under shear at the micrometer scale. By tracking embedded probe particles, we determine the local strain field, and directly measure its uniformity, or degree of affineness, on scales of 2-100 microm. The degree of nonaffine strain depends upon the polymer length and cross-link density, consistent with theoretical predictions. We also find a direct corresp...

Strain induced fluctuations in polymer networks, melts and gels (butterfly patterns)

Nonlinear shear and elongational rheology of model polymer melts at low strain rates

We present new results for the low strain rate behavior of the steady-state planar shear and elongational viscometric functions of model polymer elts, computed by non-equilibrium molecular dynamics simulations. The chain lengths in our model polymer melts vary from N = 2 up to = 100 beads, the maximum value corresponding to approximately 57 Kuhn lengths (approximately equivalent to polyethylene...

Strain-enhanced stress relaxation impacts nonlinear elasticity in collagen gels.

The extracellular matrix (ECM) is a complex assembly of structural proteins that provides physical support and biochemical signaling to cells in tissues. The mechanical properties of the ECM have been found to play a key role in regulating cell behaviors such as differentiation and malignancy. Gels formed from ECM protein biopolymers such as collagen or fibrin are commonly used for 3D cell cult...

Multi-scale strain-stiffening of semiflexible bundle networks.

Bundles of polymer filaments are responsible for the rich and unique mechanical behaviors of many biomaterials, including cells and extracellular matrices. In fibrin biopolymers, whose nonlinear elastic properties are crucial for normal blood clotting, protofibrils self-assemble and bundle to form networks of semiflexible fibers. Here we show that the extraordinary strain-stiffening response of...