Droplets, Evaporation and a Superhydrophobic Surface: Simple Tools for Guiding Colloidal Particles into Complex Materials

Abstract

Abstract:The formation of complexly structured and shaped supraparticles can be achieved by evaporation-induced self-assembly (EISA) starting from colloidal dispersions deposited on a solid surface; often a superhydrophobic one. This versatile and interesting approach allows for generating rather complex particles with corresponding functionality in a simple and scalable fashion. The versatility is based on the aspect that basically one can employ an endless number of combinations of components in the colloidal starting solution. In addition, the structure and properties of the prepared supraparticles may be modified by appropriately controlling the evaporation process, e.g., by external parameters. In this review, we focus on controlling the shape and internal structure of such supraparticles, as well as imparted functionalities, which for instance could be catalytic, optical or electronic properties. The catalytic properties can also result in self-propelling (supra-)particles. Quite a number of experimental investigations have been performed in this field, which are compared in this review and systematically explained.

Formation of Supraparticles and Their Application in Catalysis

“…The superhydrophobic nature reduced the pinning area and contributed to near-spherical or spheroidal supraparticles. 18,72 In addition to spherical supraparticles, they later obtained anisotropic, 74 anisometric, 75 and ellipsoidal 76 supraparticles by introducing magnetic field, controlling the ionic strength, and changing the shape of the superhydrophobic surface, respectively. Furthermore, the researchers came to utilize superamphiphobic surfaces to create droplets by taking advantage of its extreme liquid repellency for both polar and nonpolar solvent (Figure 2c).…”

From Single-Core Nanoparticles in Ferrofluids to Multi-Core Magnetic Nanocomposites: Assembly Strategies, Structure, and Magnetic Behavior

“…In this synthetic route, a liquid-repellent surface is used, on which ferrofluid droplets are left to dry in a controlled manner, resulting in the formation of superparamagnetic multi-core supraparticles [170,171].…”

A Review of Gene, Drug and Cell-Based Therapies for Usher Syndrome

“…Supraparticles are colloidal nanoparticle aggregates with a larger drug loading capacity relative to individual nanoparticles (Sperling and Gradzielski, 2017). Supraparticles have already been used to deliver the developmental neurotrophin, brainderived neurotrophic factor (BDNF), to the inner ear of a hearing loss guinea pig model (Wang et al, 2014).…”