Doctoral Thesis Defense

Program in Polymers and Soft Matter (PPSM)

Polymer Grafted Nanoparticles as Functional and Mechanically Robust Single-Component Composites

Josh Kubiak

Tuesday, August 10, 2021

2:00 – 3:00pm ET

Contact dmse-gradoffice@mit.edu for Zoom link.

Since their inception, polymers have been used in the formulation of composite materials that capitalize on the ease of processing, low density, and low cost of plastics while incorporating specific filler materials that enhance mechanical properties or add functionality. Synthesizing polymer matrix composites with a high content of particulate additives can maximize the particular functionality imparted by the additive phase and lead to materials with advantageous property combinations. Critically, the distribution of particulate fillers has a profound influence on the properties of the composite material. For many applications, such as optically transparent or high strength composites, maintaining a uniform distribution of non-aggregated filler is vital. Obtaining such a uniform distribution, particularly for high loadings or nanoscale particles, is a significant challenge, and substantial research and engineering effort has been dedicated to establishing methods of compatibilizing and dispersing filler particles within a polymer matrix. Of these methods, polymer grafted nanoparticles (PGNPs) provide a unique and tunable platform for controlling composite composition and mediating interparticle interactions while precluding aggregation of the particle cores. While the utility of PGNPs as filler materials has been demonstrated extensively, their independent use as single-component composites remains a rapidly developing area of investigation. A pivotal challenge in the development of PGNP composites is the trade-off between filler loading and the mechanical robustness and processability of the composite. In this work, multiple strategies for bridging this gulf are presented and investigated in order to create highly-filled, single-component PGNP composites without compromising mechanical performance or processability. Specifically, the introduction of interparticle bonds between PGNPs via traditional chemical crosslinking, thermal self-crosslinking, and embedding inside of a polymer network are explored as routes to functional nanocomposites.

Thesis Supervisor
Robert J. Macfarlane, Associate Professor, Materials Science and Engineering, Massachusetts Institute of Technology

Thesis Committee
Alfredo Alexander-Katz, Professor, Materials Science and Engineering, Massachusetts Institute of Technology

Jeremiah A. Johnson, Professor, Chemistry, Massachusetts Institute of Technology

Committee Alternate

Julia Ortony, Assistant Professor, Materials Science and Engineering, Massachusetts Institute of Technology