AC-electrokinetic manipulation of organic-inorganic polymeric coacervates

Complex Coacervates are aqueous liquid-liquid phase separating materials formed between charged macromolecules, including polyelectrolytes, proteins, and charged nanocolloids. Coacervates have been applied for storage and recovery of biomasses in biomimetic aqueous environment in food and pharmaceutical industry and recently explored to remove trace organic molecules and industrial contaminates for water treatment. To enable large scale industrial application, we have recently explored rich ac-electrokinetics to manipulate and assemble complex coacervates in aqueous media using coacervates formed between polyelectrolytes and charged macroions such as polyoxometalates (POMs) and quantum dots (QDs). When applied ac-electric field exceed a critical value, we observe the droplet-like coacervate formation and chain-like coacervate assembly in response to dielectrophoresis (DEP) in non-uniformed ac-fields across two coplanar microelectrodes. The critical ac-field strength for POM-based coacervate formation varies considerably from that for QD-based coacervate formation, clearly indicating the effect of nanocolloidal surface charge density on ac-electrokinetic characteristics. More intriguingly, as fine tuning ac-frequency, we observe the in-situ droplet-in-droplet dual complex coacervate formation in aqueous media. The combination of DEP-induced complex coacervate formation and assembly is further integrated with ac-electrospinning to enable the nanomanufacturing of functional coacervate fibers and membranes for practical biomedical and environmental applications.