Directed Self-Assembly of sub-10 nm Particles: Role of Driving Forces and Template Geometry in Packing and Ordering

Abstract

By comparing the magnitude of forces, a directed self-assembly mechanism has been suggested previously in which immersion capillary is the only driving force responsible for packing and ordering of nanoparticles, which occur only after the meniscus recedes. However, this mechanism is insufficient to explain vacancies formed by directed self-assembly at low particle concentrations. Utilizing experiments, and Monte Carlo and Brownian dynamics simulations, we developed a theoretical model based on a new proposed mechanism. In our proposed mechanism, the competing driving forces controlling the packing and ordering of sub-10 nm particles are (1) the repulsive component of the pair potential and (2) the attractive capillary forces, both of which apply at the contact line. The repulsive force arises from the high particle concentration, and the attractive force is caused by the surface tension at the contact line. Our theoretical model also indicates that the major part of packing and ordering of nanoparticles occurs before the meniscus recedes. Furthermore, utilizing our model, we are able to predict the various self-assembly configurations of particles as their size increases. These results lay out the interplay between driving forces during directed self-assembly, motivating a better template design now that we know the importance and the dominating driving forces in each regime of particle size.

Joint effect of advection, diffusion, and capillary attraction on the spatial structure of particle depositions from evaporating droplets

“…Depositions of microgel soft particles are characterized by a gradual order-to-disorder transition [25], which is not abrupt like the hard colloid depositions [17,25]. The transition from order to disorder is also observed in the structures obtained by a dipcoating technique [32][33][34]. Li et al used solvents with dendrimers and obtained annular structures of a periodic thickness [26].…”

“…There are several discrete models, which explicitly describe the dynamics of each particular particle. These models are usually based on Monte Carlo or molecular dynamics methods [33,41,[43][44][45][46][47]. Some Monte Carlo based models are lattice models [48][49][50], and some are not [27,51,52].…”

Promotion of Self-Assembly Patterning of FePt Nanoparticles by Tuning the Concentration of Oleylamine/Oleic Acid Surfactants in a Coating Solution

“…The dropped nanoparticles first moved on the substrate surface according to the convection flow aroused from solvent vaporization; subsequently, they were closely packed at a certain interparticle distance when the capillary force and the steric repulsion of the surfactants balanced. 16,17 The interparticle distance is determined by the layer thickness of the surfactants covering the nanoparticle surface. The -COOH group in OAc and the -NH 2 group in OAm tend to chemically bond to Fe and Pt metals, respectively.…”

Template-Assisted Self Assembly of Fluorescent Nanodiamonds for Scalable Quantum Technologies

“…TASA combines the flexibility and precision of nanolithography with the scalability of colloidal assembly. It has been used to position individual nanoparticles, as well as to direct the orientation of anisotropic particles, of various materials [23][24][25][26][27][28][29][30]. By using these arrays and an automated optical measurement system, we study the statistical het-erogeneity of the nanodiamonds' structural, optical, and spin properties.…”