From Aqueous Dispersions to Functional Materials: Capillarity and Electrostatic Adhesion

Abstract

The author was first acquainted with polymer lattices as model particles for studying sedimentation phenomena, evolving towards the elucidation of synthetic and natural latex heterogeneity and microchemistry. This brought new elements to understand the remarkable mechanical properties of natural rubber, leading to the latex route for making nanocomposites. These materials show exceptional properties that are largely due to electrostatic adhesion, a concept that had been previously presented by Deryagin but was later abandoned. Electrostatic adhesion is the outcome of ion partition and self-assembly within drying aqueous dispersions, producing co-existing domains with opposite charges. Their examination allowed several experimental observations leading to the proposal of mechanisms to explain hitherto challenging electrostatic phenomena shown by solids and liquids. Water plays a decisive role in all the different phenomena described in this account.

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“…more recently, the various scanning electric probe microscopies derived from AFm allowed the direct observation of local charge excess in a solid with nanometer resolution and the detection of electrostatic contributions to adhesion, in several systems (Galembeck et al 2013). New models of electrostatic adhesion were developed, based on ion partition not only at interfaces but also in the bulk phases that were successfully verified by measuring the elastic modulus of nanocomposites (Galembeck 2018). A schematic description of electrostatic adhesion where cations hold together the negative surfaces of clay and rubber latex particles is in Figure 5.…”