• Sara Laura Wilson

Effect of Crosslinks on Mechanical Properties of High Inorganic Content Nanocomposite Films

Updated: May 15

Macfarlane Research Group at MIT

June 2017 — May 2018

Position: Undergraduate Researcher (UROP)

Honor: Johnson & Johnson UROP Scholar, 2017

Nanocomposite Tectons (NCTs), developed by the Macfarlane Group, are nanocomposites that self-assemble into ordered structures, allowing for control over both the properties and the structure of crystalline solids. NCTs consist of an inorganic core molecule, a polymer graft, and a supramolecular binding group.

For this project, I specifically looked at NCTs with polymer grafts that are in the concentrated particle brush regime and the semi-dilute particle brush regime. For a material in the concentrate brush regime, the polymer chains are tightly packed, forcing them into an extended conformation. As a result, the particles act as pseudo-hard spheres, and the chains do not entangle. When the chain length is increased, the particle enters the semi-dilute brush regime, in which the chain segments at the outside of the particle are loosely packed and capable of entangling. Previous work has shown that particles capable of entangling produce materials of significantly higher toughness. I directly compared how supramolecular bonding and entanglement affect mechanical properties. This work involved synthesizing uniform silica nanoparticles, learning to grow polymer chains from their surface, and functionalizing the polymer with assembly groups.

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