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Interfacial Instability of Emulsion Droplets Containing a Polymer and a Fatty Alcohol
journal contribution
posted on 2020-03-31, 19:36 authored by Shanqin Liu, Xuanhe Li, Linfeng Hu, Shaohuan Deng, Wanqing Zhang, Pengfei Liu, Yuping ZhangWe
investigated the interfacial instability of emulsion droplets
via in situ measuring the oil/water interfacial tension (IFT) using
the capillary suction method. The discrete phase of the oil-in-water
emulsion contains a hydrophobic polymer (polystyrene, PS) and a fatty
alcohol cosurfactant n-cetyl alcohol (CA) or n-octadecanol (OD), both of which were dissolved in an organic
solvent (chloroform). The continuous phase is an aqueous solution
of surfactant (sodium dodecyl sulfate, SDS). Upon removal of the organic
solvent, the concentrations of CA and PS increase gradually, which
induce a continual decrease of the IFT until the occurrence of interfacial
instability. Micropipette tensiometry performed on an evaporating
emulsion droplet reveals that interfacial instability is triggered
when the IFT decreases close to ∼0.17 mN/m. As a result, micron
particles with wrinkled surfaces can be obtained after the complete
removal of the organic solvent. The effect of the initial concentration
and alkyl chain length of the cosurfactant on the interfacial instability
and surface roughness of the formed particles was studied. This study
provides theoretical guidance for the preparation of micrometer-sized
polymer particles with diverse morphologies via the interfacial instability
of emulsion droplets.