Author: Omid Jahanmahin

Publisher:

Published: 2023

Total Pages: 0

ISBN-13:

Shedding some light on the hidden layers of nanoparticle assembly techniques and mechanisms will allow scientists and engineers to gain a higher degree of controllability when designing nanostructures with customized optical, electric, and magnetic properties for various applications such as sensing platforms, medical diagnostics, particle filtration, energy storage devices, flexible LEDs, lasers, selective catalysts, solar cells, electronic skin, etc. In one of our works, we developed a model to account for all the involved electrostatic and van der Waals interactions to study the silica-coated gold nanowire (NW) self-assembly on gold stripes on a glass substrate. Monte Carlo simulations of NW self-assembled patterns were consistent with experimental results. It was found that although NW-stripe vdW is essential to bring NWs atop the stripes, it has a negative impact on the final NW alignments. Further, it was shown that charge nonuniformity arising from extra charges at the end of NWs plays a crucial role in forming final, well-ordered structures on top of the Au stipes. We also studied individual and binary colloidal particle assemblies of TiO2, SiO2, and PMMA on top of or around the photoresist posts for various frequencies and voltage levels using the reconfigurable assembly method of dielectrophoresis (DEP). Monte Carlo simulations based on our developed model depicted consistent results with experimental observations, except for co-assemblies of TiO2 with SiO2 or PMMA. The abnormal behavior of TiO2 in the presence of SiO2 and PMMA particles and not showing a crossover from pDEP (around the posts) to nDEP (top of the posts) similar to individual TiO2 assemblies has been investigated to reveal the underlying causes. To study the oriented attachment (OA) mechanism of Pt cuboctahedron nanocrystals (NCs) in the presence of HCl and water, and only water, we performed atomic-scale investigations using reactive force field (ReaxFF) MD simulations and advanced rare event sampling techniques. Four different configurations of high and low pH with attachment pathways of 100-100 and 111-111 were assessed to explain the fundamental reasons behind the preferential attachment of two Pt NCs switching from 100-100 at high pH to 111-111 at low pH. The final simulation outcomes were in harmony with the experiment's findings. Our developed framework for the OA of Pt NCs can be applied to study similar rare event systems with liquid-metal interfaces.