Visualization and characterization of interfacial polymerization layer formation

We present a microfluidic platform to visualize the formation of free-standing films by interfacial polymerization. A microfluidic device is fabricated, with an array of micropillars to stabilize an aqueous-organic interface that allows a direct observation of the films formation process via optical microscopy. Three different amines are selected to react with trimesoyl chloride: piperazine, JEFFAMINE((R))D-230, and an ammonium functionalized polyhedral oligomeric silsesquioxane. Tracking the formation of the freestanding films in time reveals strong effects of the characteristics of the amine precursor on the morphological evolution of the films. Piperazine exhibits a rapid reaction with trimesoyl chloride, forming a film up to 20 mu m thick within half a minute. JEFFAMINE((R))D-230 displays much slower film formation kinetics. The location of the polymerization reaction was initially in the aqueous phase and then shifted into the organic phase. Our in situ real-time observations provide information on the kinetics and the changing location of the polymerization. This provides insights with important implications for fine-tuning of interfacial polymerizations for various applications.