Designing Block Polymer-Based Membranes with Tailored Surface Chemistry

In this dissertation, we address the most immediate concern of water stress by purposing a potential option for the freshwater production through engineered polymeric membranes. Despite the demonstrated success of state-of-art filtration membranes, the performance of current membrane-based separations is limited by a trade-off between the solute selectivity and hydraulic permeability. It is critically important to prepare membranes with well-defined structures (i.e., high porosity with a well-defined pore size) in a controllable manner. Furthermore, to meet the growing demand of adsorptive membranes that selectively remove harmful contaminants, the attachment of a robust binding ligand is strongly desired. Membranes based on block polymer precursors are an emerging class of promising multifunctional separation devices due to their simple to control macromolecular architecture and tailorable surface chemistry. This dissertation presented the design, fabrication and characterization of block polymer-based advanced functional membrane with tailored chemistry. In general, two different membrane architectures, a self-assembled block polymer membrane with a thin selective layer and a homogeneous phase inversion membrane with surface segregated ligands were purposed. Membrane architectures are controlled with proper nanofabrication techniques to target the desired performance profiles. Moreover, tailored chemical functionalization that modified the surface chemistry of these membranes offer a highly tunable platform that defines myriad material properties for designated applications. The self-assembled nanostructure based on the direct design of polyisoprene-b-polystyrene-b-poly(2-acrylamido-ethane-1,1-disfulonic acid) (PI-PS-PADSA) enables a highly selective nanofiltration membrane that is capable of fully gating solutes with an 8 Å difference in size. Meanwhile, the polystyrene-b-poly(acrylic acid) preferentially segregates to the surface of the polysulfone matrix and functions as highly efficient heavy metal purification device with robust adsorption performance (i.e., 99+% removal of dissolved metal ions). The rational design of block polymer-based membranes promises to provide new separation archetypes for advanced membrane applications yet to be precisely engineered.