Polyelectrolytes of Inorganic Polyoxometalates: Prospecting New Charged Polymers for Advanced Applications

Abstract

Polyelectrolytes are charged polymers comprising macromolecules in which substantial portions of the constituent units contain cationic (e.g., pyridinium, ammonium) or anionic (e.g., sulfonate, carboxylate) groups, which possess special functions from the features of counterions, such as dissociation to charged species, mechanical stability, phase behavior, etc. Therefore, functional polyelectrolytes have been widely applied in many fields. In this perspective, we present some progresses in the studies of poly(polyoxometalate)s, denoted as poly(POM)s, as a kind of new charged polymers/polyelectrolytes, by covalent bonding between the inorganic polyoxometalate (POM) clusters and the organic polymer chains. According to the distinct positions of POMs in polymer chain and functions of poly(POM)s, they are divided into the following four categories: crosslinked poly(POM); side-chain poly(POM); backbone poly(POM), including poly(POM)-conjugated polymer hybrid and block poly(POM)-polymer; and POM-based covalent organic framework (PCOF). This perspective introduces the synthesis methods of poly(POM) polyelectrolytes and their macromolecular and aggregate structural characteristics, while also focusing on their properties and functions. Their application areas include catalysis, thermal resistance, optical functions, fuel cells and batteries, etc.