On particle bridging by small charged molecules

Abstract

Particle bridging by small charged molecules was discovered quite recently. Only specific compounds with the appropriate structure and spatial position of the charged groups, display bridging behaviour. These compounds as a new class of functional additives are highly suitable for making strong gels and paste products. This type of bridging is highly directed towards maximising the strength of the flocculated network in dispersions. The small size of the molecules means that bridging can only take place at the closest point of interaction between particles (particle-particle bond) in the flocculated state, thus greatly strengthening the interparticle bond in the three-dimensional network. The yield stress is a measure of the strength of the network. Particle bridging by small molecules can increase the maximum yield stress (at zero net charge condition) by as much as 10-fold. In this paper the elements of molecular structure of additives essential for bridging are discussed.