With the goal of ultimately deciphering the design principles for biomimetic materials that can autonomously stiffen and soften, we investigate colloids as a model system that can dynamically transition from fluid-like (sol) to gel-like (gel) when crosslinked with polymers. The model was first developed with colloids only, interacting via a Lennard-Jones potential and undergoing Brownian dynamics, with experimentally relevant parameters, to test and refine the simulation. We then added polymer crosslinkers that connect the colloids via an attractive spring force, and investigate resulting collective properties, such as the time needed for the formation of system spanning networks and the elastic moduli, for various colloid densities, interaction strengths, and cross-linker rest lengths and densities. Using experimental parameters for polystyrene spheres and Bovine Serum Albumin (BSA) crosslinkers, we predicted the behavior of real systems. Finally, we replaced the passive, one-shot crosslinkers in our system by active cross-linkers that can dynamically and attach and detach, and characterized how the degree of order and the mechanical response of the system change with time. Our results provide insights into the design of self-sustaining soft materials that can dynamically stiffen and soften, and how the properties of such materials can be tuned.
Materials Science and Engineering (MS)
Department, Program, or Center
School of Chemistry and Materials Science (COS)
Rennert, Elizabeth, "Investigating dynamic stiffening and softening of a system of colloids cross-linked via polymers" (2019). Thesis. Rochester Institute of Technology. Accessed from
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