la7b02925_si_001.pdf (512.98 kB)
Effects of Salt-Controlled Self-Assembly of Triblock Copolymers F68 on Interaction Forces between Oil Drops in Aqueous Solution
journal contribution
posted on 2017-12-02, 00:00 authored by Hang Jin, Wei Wang, Hongli Chang, Yun Shen, Zhipeng Yu, Yunya Tian, Yang Yu, Jing GongNonionic
triblock copolymers, surfactant Pluronic F68 (PEO76–PPO29–PEO76),
are widely used in industrial processes, such as foaming, emulsification,
and stabilization. The behaviors of triblock copolymers such as the
salt-dependent self-assembly in bulk solution and the irreversible
adsorption at the oil/water interface are mainly focused to explore
their effects on the interaction forces between nano-spacing interfaces
of oil droplets. In this study, the atomic force microscopy (AFM)
technique was employed to measure the drop interaction forces with
different F68 bulk concentrations. All selected bulk concentrations
(≥100 μM) of copolymers can ensure the formation of a
stable layer structure of stretched polymer chains (“brush”)
at the oil/water interface, which behaved as a mechanical barrier
at the interface. This study quantified the forces caused by the space
hindrance of F68 copolymers both in the bulk phase and at the interface
of oil/F68 aqueous solution during drop interaction. The effects of
monovalent electrolyte (NaCl)-induced self-assembly behavior of triblock
copolymers F68 in bulk solution on drop interaction forces were measured
through the AFM technique.