Title: Reactions at Liquid-Liquid Interfaces

Advisor: Todd Squires

Abstract:

Reactions at liquid-liquid interfaces are important for a variety of fields, from novel material synthesis, to food processing, or biochemical processes. For example, the active layer of reverse osmosis (RO) membranes are produced by interfacial polymerization. Reaction kinetics for polyamide RO membrane production are difficult to obtain and seldom reported due to the rapid (~seconds) formation of a thin film. Here, film formation is studied using a microfluidic, interferometry-based technique to measure monomer concentration near the interface as the reaction occurs. Our results are consistent with a polymerization reaction that is initially controlled by a reaction-diffusion boundary layer within the organic phase. Using simple scaling arguments and finite element modeling to interpret our data, we report the first measurements of the reaction rate constant for this system. By understanding and taking into account the transport/partitioning of monomer, we have been able to explore the effects of solvents and temperature on the reaction.

The platform discussed is general to studying the transport of any solute across an interface. As such, I demonstrate the ability to measure equilibrium partition coefficients and dynamic partitioning of solute locally to an interface.