(594a) Polymeric Membranes for the Filtration of Oil/Water Nanoemulsions

In recent years, growing environmental concerns have fueled the need for efficient oil and water separation systems. Membranes leveraging contrasting wetting properties have received significant attention for their ability to selectively permeate one component while rejecting the other. However, separation of droplets below a micron in size remains a key challenge. Examination of the wettability characteristics of a membrane gives rise to the concept of the breakthrough pressure - the maximum transmembrane pressure at which a membrane can operate retaining high selectivity. These separation principles are experimentally verified using a model system of through-pore membranes chemically engineered with desired wetting properties. To overcome the flux limitations imposed by the breakthrough pressure, we extend our findings to hierarchical polymeric membranes. A novel fabrication scheme is employed to control the skin layer thickness to optimize the permeability, and we demonstrate separation of droplets that are well below a micron in size in this system. By reducing the skin thickness layer by a factor of four, the permeability was improved significantly. These simple yet robust hierarchical membranes with engineered wetting characteristics show promise for the large-scale, efficient separation systems