November 23, 2024
Nargess Mehdipour

Nargess Mehdipour

Academic Rank: Associate professor
Address:
Degree: Ph.D in -
Phone: -
Faculty: Faculty of Nano and Biotechnology

Research

Title
Molecular Dynamics Simulation of Mechanisms of Self-Assembly in Triblock Patchy Particles
Type Thesis
Keywords
self assembly, simulation, patchy particles
Researchers Ali Gharibi (Student) , Hossein Eslami (Primary advisor) , Nargess Mehdipour (Advisor)

Abstract

Patchy particles are a new class of colloidal particles with anisotropic interactions. Such particles have the capability of self-assembling to diversity of open lattice with promising applications in drug delivery, catalysis, photonic crystals, and novel structural and functional materials. Particularly, the patchy colloidal particles are regarded as building blocks for selfassembly to intended structures. The number, width, and locations of patches play an effective role in determining the architecture of the self-assembled structure. Thus far, many experimental studies have been done for the synthesis of patch particles. However, due to experimental limitations, the mechanism of self-assembly of patchy colloidal particles has less been the subject the experiment. On the other hand, computer simulations are powerful tools in understanding the mechanism of self-assembly, crystallization, and the roles of building blocks in determining the architecture of self-assembled structures. In this study, we have developed a detailed model (including a substrate, solvent, the chemical details of the patches, and surface charges) to understand the self-assembly mechanism of patchy particles. Our findings showed that in addition to multiple nucleation in the system, the nucleation of the selfassembled lattice (kagome for two-patch particles) follows a two-step mechanism. Upon crystal growth, the growing crystals form aligned and misaligned facets at the grain boundaries. Because of mismatch in the lattice planes of neighboring crystals, the growth of less stable (smaller) nuclei is stopped. Such nuclei undergo surface melting to form liquid-like particles, which subsequently displace and reorient to attach to the interface of more stable (bigger) neighboring nuclei. Besides, multiple postcritical nuclei are formed in simulation box. Such incomplete nucleation/growth mechanism is in complete agreement with recent experiments. The solid-solid (hexagonal-to-kagome) phase transiti