Application of Polymer Kinetics and controlled Self-Assembly in multi-dimension Nanomaterial Synthesis
Interest in nanomaterials has risen in the recent past, primarily due to the unique properties of materials at the nanoscale. There are two main approaches to nanomaterial synthesis, viz; top-down (fragmentation) and bottom-up (self-assembly driven). Coupled approaches, however, have potential to give unprecedented control over material synthesis. We employed a top-down approach to increasing etch rate, and bottom-up approach to synthesize nano-sized beams, sheets, and cubes. Onedimensional coordination polymers were grown at steady-state conditions — achieved through solubility-limited etching of liquid metal alloys. Stoichiometric control of substitution around the central metal atom leads to asymmetry in substitution patterns, which in turn influences the self-assembly of these 1D polymers. Therefore, three separate growth rates exist; K1 (polymerization), K2 (x-y plane assembly), K3 (x-z plane assembly). These growth rates can be engineered to affect the self-assembly process to construct various nanomaterials including cubes (K1≈K2≈K3), sheets (K1≈K2>>>K3), and beams (K1>>>K2>K3). All materials were characterized by scanning/tunneling electron microscopy (SEM, TEM), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction.