Interaction Forces between Hydrophobized Surfaces with Adsorbed Layers of Triblock Copolymers Evaluated by Atomic Force Microscopy

Abstract

Interaction forces between hydrophobized silica surfaces in aqueous Pluronic F127 and P123 solutions with added NaCl were studied by atomic force microscopy. The forces were dominated by steric repulsion between adsorbed polymer layers. Below the critical micelle concentration (CMC), increasing salt concentration reduced repulsion for F127 and induced attraction for P123 due to dehydration of poly(ethylene oxide) chains. Above the CMC, dehydration of adsorbed hemimicelles altered their structure and surface binding, thereby significantly affecting the interaction forces.