Dilute suspensions of Janus rods: the role of bond and shape anisotropy

TL;DR

This study uses Monte Carlo simulations to explore how particle shape and surface patchiness influence the self-assembly of Janus rods, revealing how anisotropy controls aggregate structures and potential applications in nanoreactors.

Contribution

It combines shape and bond anisotropy in simulations to understand their combined effect on nanoparticle assembly, a novel approach for designing nanostructures.

Findings

Shape anisotropy suppresses spherical Janus phases.

Tuning interaction parameters promotes spherical micelle formation.

Elongated particle clusters may enhance storage and catalytic properties.

Abstract

Nanometer-sized clusters are often targeted due to their potential applications as nanoreactors or storage/delivery devices. One route to assemble and stabilize finite structures consists in imparting directional bonding patterns between the nanoparticles. When only a portion of the particle surface is able to form an inter-particle bond, finite-size aggregates such as micelles and vesicles may form. Building on this approach, we combine particle shape anisotropy with the directionality of the bonding patterns and investigate the combined effect of particle elongation and surface patchiness on the low density assembly scenario. To this aim, we study the assembly of tip-functionalised Janus hard spherocylinder by means of Monte Carlo simulations. By exploring the effects of changing the interaction strength and range at different packing fractions, we highlight the role played by shape and bond anisotropy on the emerging aggregates (micelles, vesicles, elongated micelles and lamellae). We observe that shape anisotropy plays a crucial role in suppressing phases that are typical to spherical Janus nanoparticles and that a careful tuning of the interaction parameters allows to promote the formation of spherical micelles. These finite-size spherical clusters composed of elongated particles might offer more interstitials and larger surface areas than those offered by micelles of spherical or almost-spherical units, thus enhancing their storage and catalytic properties.