Electrostatic Heteroaggregation: Fundamentals and Applications in Interfacial Engineering

Abstract

The aggregation of oppositely charged soft materials (particles, surfactants, polyelectrolytes, etc.) that differ in one or more physical or chemical attributes, broadly referred to as electrostatic heteroaggregation, has been an active area of research for several decades now. While electrostatic heteroaggregation (EHA) is relevant to diverse fields such as environmental engineering, food technology, and pharmaceutical formulations, more recently there has been a resurgence to explore various aspects of this phenomenon in the context of interface stabilization and the development of functional materials. In this Feature Article, we provide an overview of the recent contributions of our group to this exciting field with particular emphasis on fundamental studies of electrostatic heteroaggregation between oppositely charged systems in the bulk, at interfaces, and across the bulk/interface. The influence of the size and shape of particles and the surface charge of heteroaggregates on the formation of Pickering emulsions and their utilization in the development of porous ceramics is discussed.

Re-expansion modeling to understand the electrostatic interaction between charged core–shell structured particles

“…Electrostatic interactions between charged particles are prevalent in various scientific and engineering domains, including electrostatic aggregation and the coalescence of a colloidal system [1], the coagulation of charged aerosol particles in an electrostatic precipitator [2], and the electrostatic adhesion of dust on a solar panel [3]. Core-shell structured composite particles have attracted significant research interest in recent years owing to their unique properties [4,5].…”

Formulation of Antioxidant Composites by Controlled Heteroaggregation of Cerium Oxide and Manganese Oxide Nanozymes

“…Numerous materials of various structures and compositions have been found to mimic such enzymes including metallic nanoparticles (Ag, Au, and Pd), − metal oxides (Co 3 O 4 , CeO 2 , and V 2 O 5 ), − metal chalcogenides (FeS, MoS 2 , and WS 2 ), − clays, , carbon materials (fullerenes and carbon nanotubes), biopolymers, , and metal–organic frameworks . The surface functionalities and parameters of nanoparticles such as metal oxides often result in the aggregation of the bare and primary particles into clusters of various sizes, depending on the experimental conditions in the system such as ionic strength, the presence of polyelectrolytes, and the nature of the solvents. − In addition, many metal oxide particles are characterized by an isoelectric point (IEP), , at which the particles have no surface charge and tend to undergo heavy aggregation that results in the loss of the surface area, which could lead to a significant reduction of the enzymatic activity.…”

“… 33 The surface functionalities and parameters of nanoparticles such as metal oxides often result in the aggregation of the bare and primary particles into clusters of various sizes, depending on the experimental conditions in the system such as ionic strength, the presence of polyelectrolytes, and the nature of the solvents. 34 − 36 In addition, many metal oxide particles are characterized by an isoelectric point (IEP), 37 , 38 at which the particles have no surface charge and tend to undergo heavy aggregation that results in the loss of the surface area, which could lead to a significant reduction of the enzymatic activity.…”

Colloidal Interactions of Microplastic Particles with Anionic Clays in Electrolyte Solutions

“…These phenomena, as well as the stability of the occurring particles, are further influenced by solution properties (e.g., pH, ionic strength, and natural organic matter content), as well as the features of the plastics (e.g., particle size, shape, and chemical composition) and other colloidal particles (e.g., composition, size distribution). ,,,, Furthermore, the mass ratio and the surface charge of the interacting particles are also important, while the electrostatic forces have been proven to play a key role in the formation of heteroaggregates. – Numerous studies have explored the impact of ionic strength on heteroaggregation, with emphasis on specific particle ratios. , The critical coagulation concentration (CCC) for heteroaggregation (at a given particle mass ratio) has been identified as being highly sensitive to boundary conditions, especially when one of the particles approaches the charge reversal point. This sensitivity can be attributed to the interplay of double-layer forces between charged and neutral particles, which is highly influenced by the charge regulation characteristics of the weaker charged surface.…”