Elucidation of the Effect of Chain Dispersity on Microstructure and Mechanical Properties of Brush Particle Assembled Material

 The field of nanocomposites emerged as a reconciliation of desirable features each from inorganic  particles (e.g., their capability for unique structural assemblies, conductivity, and quantum-scale  plasmonic character) and organic polymers (e.g., flexibility, toughness, processability, and  chemical versatility). Grafting of the polymer component to the surface of the inorganic  nanoparticle resulted in a new type of hybrid building block called brush particles, that enable  uniquely tunable homogeneous nanoparticle self-assemblies within a mechanically robust polymer  matrix. Nanocomposites often demand high inorganic loading, controllable and homogeneous  particle microstructure, and tunability of properties. To this end, several features of brush particle  material were explored. Molecular weight dispersity in the polymer canopy, inspired by long,  entanglement-forming chain toughening mechanisms, was shown to exhibit significantly higher  energy dissipation till failure through craze formation, at lower organic loadings than uniform  molecular weight distributions. This was accomplished with no detriment to the microstructural  uniformity. Additionally, isotropic microstructural trends were observed through multimodal  microstructure characterization (via electron microscopy and X-ray scattering), and spurred  examination of brush particles as a candidate for hyperuniform material formation. Finally,  machine learning regression tools were explored in an effort to establish predictive mapping from  the broad, tunable parameter space of brush architecture to desirable properties. The findings  presented in this work have made distinct strides in the effort to elucidate strengthening  mechanisms and microstructural character of brush particle materials as functions of the  architecture, and will spur further explorations into the fundamental phenomena governing these  interactions.