Hyperbranched poly(amido amine) as an effective demulsifier for oil-in-water emulsions of microdroplets

•A convenient synthetic process for hyperbranched polymer is developed.•H-PAMAM is an effective demulsifier for O/W emulsions of microdroplets with 91% of oil removal ratio.•DLS observation provides a new evidence to explore the demulsification mechanism.

The destabilization of oil-in-water (O/W) emulsions with average oil droplet sizes of less than 2 μm is important. Herein, hyperbranched poly(amido amine) (h-PAMAM) is successfully designed and synthesized by controlling the ratio of methyl acrylate (MA) to ethylenediamine (EDA) to enable the demulsifier to break microdroplets. The investigations on the effects of dosage, temperature, and settling time reveal that the demulsifier h-PAMAM with many NH2 terminal functional groups displays a satisfactory demulsification performance. The oil removal ratio can reach 91% within 30 min at the demulsification equilibrium with the addition of h-PAMAM. This ability is primarily ascribed to the hyperbranched topology and abundant amino groups of h-PAMAM. Furthermore, measurements of the rupture rate constants of oil droplets and interfacial tension indicate that h-PAMAM is an excellent demulsifier. Dynamic light scattering (DLS) analysis can provide a new evidence for the exploration of the demulsification mechanism. The effective demulsification performance of h-PAMAM supports its potential applications in petroleum engineering.

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