(470g) Assembly of Nanoparticle-Polyelectrolyte Membranes at Water-Water Interfaces

Complexation between polyelectrolytes (PEs) and nanoparticles (NPs) have been used to assemble functional films and membranes that respond to multiple inputs and stimuli. Interfacial complexation between oppositely charged polyelectrolytes and nanoparticles at the interface of aqueous two-phase systems has emerged as a powerful method to assemble these functional membranes. Remarkably, these membranes can grow continuously to thicknesses approaching 1 cm, naturally raising the question as to what is the underlying mechanism for the growth of these membranes. By taking advantage of a microfluidic setup, we study the growth mechanism behind interfacial complexation between silica (SiO₂) nanoparticles and Polydiallyldimethylammonium chloride (PDADMAC). The sequential insertion of PDADMAC and fluorescently labelled PDADMAC has shown that the membranes grow through a permeation mechanism, in which PEs diffuse and permeate continuously to the growing front of the membrane. Taking advantage of this growth mechanism, we demonstrate that PDADMAC/SiO₂ nanoparticle membranes can be spatially structured to embed specific functionality, which could potentially be useful for programmed delivery of actives from the membrane.