Improvement of millimeter-scale double droplets stability through synergistic noncovalent interactions

Driven by the need to prepare stable double droplets (the precursor of polymer shells for the laser-driven inertial confined fusion (ICF)) with surfactant concentration as little as possible, a synergistic noncovalent interaction route of the hydrophilic and hydrophobic interactions, hydrogen bonding and electrostatic repulsion to improve the oil-water interface performance has been proposed. Both the adsorption layer thickness and the adsorbed amount of the surfactants on the oil-water interface increase due to the formation of the hydrogen bonding between the poly(vinyl alcohol) (PVA) and polyelectrolytes (polystyrene sulfonate sodium (PSSS) or poly(acrylic acid) sodium salt (PAAS)), leading to the improvement of the interface viscoelasticity and the decrease of the interfacial tension compared with that of the polyelectrolytes alone. Therefore, owing to the synergistic noncovalent interactions, the stability of millimeter-scale double droplets is improved and monodisperse polymer shells have been successfully prepared from these stable double droplets by solvent evaporation method. This work provides more in-depth insights of the synergistic effects of the surfactants on the double droplets stability and gives some guidance on the optimization of the surfactants, benefiting the preparation of monodisperse polymer shells for ICF.