(431d) Computer Simulation of Nanoparticle Solutions in Confinement

Nanometer-sized particles possess extraordinary properties that are not available in either isolated molecules or bulk materials. To fully realize their potential, nanoparticles need to be fabricated into predesigned nanostructures or multidimensional ordered arrays. Significant progress has been made recently in synthesizing surfactant-capped nanoparticles that are dissolvable in typical non-polar solutions and capable of self-assembling into ordered arrays when deposited on a smooth surface or at a water-air interface. We study the feasibility of a new assembly route, namely using nanoscale confinement to promote the assembly of surfactant-capped nanoparticles. We first use the molecular dynamics simulation technique and atomistic models to investigate the interactions and behaviors of nanoparticle monomers and oligomers dissolved in hexane confined between two solid surfaces. We show that by applying proper perpendicular and parallel pressures on the confined nanoparticle solutions, nanoparticles form ordered aggregates. The nanoparticle interactions and the simulation system are then coarse grained to perform Brownian Dynamics simulations to study nanoparticle assembly facilitated by nanoconfinement over larger time and length scales. We conclude that nanoscale confinement with proper pressure control could be a new useful strategy for promoting nanoparticle self-assembly.