Browsing by Author "Chen, Sihan"

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    Mechanics of Biopolymer Networks
    (2023-08-08) Chen, Sihan; MacKintosh, Fred C.
    Biopolymer networks pervade living systems, appearing in diverse structures from the cellular cytoskeleton to the extracellular matrix at the tissue level. Besides their biological significance, these networks exhibit a variety of physical phenomena arising from the collective interactions of biopolymers. One example is the cytoskeletal networks, which are continually driven out of equilibrium by the hydrolysis of adenosine triphosphate (ATP), engendering unique non-equilibrium dynamics such as force generation. Furthermore, bending fluctuations within these networks generate intriguing dynamical viscoelastic properties. Most notably, recent research has unveiled a mechanical critical phase transition in the nonlinear elasticity of athermal fiber networks. This dissertation proposes several theoretical frameworks tailored to shed light on the physics of the mechanical properties intrinsic to biopolymer networks. The first part of the thesis introduces a theoretical mechanism for the non-equilibrium force generation within cytoskeletal networks, particularly in scenarios where molecular motors are absent. Following this, we establish a theoretical model to quantify the nonlinear viscoelasticity exhibited by networks composed of transient crosslinkers. Progressing further, we construct a non-affine effective medium theory (EMT) to delineate the linear elasticity of biopolymer networks. Finally, we extend the EMT to capture the nonlinear elasticity and apply it to study the mechanical phse transition of fiber networks.