Self-assembly of spheroidal triblock Janus nanoparticle solutions in nanotubes

Abstract

We have performed coarse-grained molecular simulations to investigate the morphologies and phase diagrams of self-assembled spheroidal triblock Janus nanoparticles (JNPs) confined in nanotubes. Nanoparticles exhibit several unique behaviours through shape changes, such as high thermal conductivity in heat pipes, high strength of binding avidity in ligand–receptor interactions, high amounts of uptake between cells during endocytosis processes, and so on. In this study, we focus on the effect of shape on self-assembled structures or phases within nanospaces. We derived qualitative phase diagrams of axial pressure versus the ratio of the diameter of the nanoparticles and nanotubes. Two distinct types of nanotube walls and three types of JNP shapes were considered: hydrophobic and hydrophilic walls, and NP aspect ratios of 1.5, 2.0, and 2.5. We observed diverse morphologies in spheroidal JNP solutions, many of which have not been observed before in bulk solutions. We also compared the self-assembled structures of spherical triblock JNPs. By increasing the aspect ratio of the NPs, clusters of unique structures, such as tripods, tetrapods, and hexapods, were formed. Moreover, we found that an increase in the value of the aspect ratio leads to a shift in the multilayer toroidal stacking phases to a weaker confinement effect. The self-assembly behaviours of the spheroidal JNPs can be qualitatively predicted based on the chemical nature of the nanotube walls and shapes of the JNPs.