The broader impact/commercial potential of this Small Business Innovation Research (SBIR) project is in the development of novel water treatment technologies that can improve access to clean water and reduce the cost of water treatment. The innovation is a drop-in-replacement nanofiltration membrane that is chlorine-resistant, highly permeable, and uniquely customizable. The chlorine resistance allows for the continuous chlorination of the membrane, which can reduce bio-fouling and thereby increase the lifespan of a membrane; this has been a chief innovation target for more than 30 years. The customizability aspect also facilitates capture of lead and other heavy-metals, broadening the reach of nanofiltration membranes to sectors that generate significant amounts of wastewater, such as semiconductor, mining, pulp-and-paper, and colorant industries. These improvements to nanofiltration technology have clear and direct societal and economic impact by facilitating water reuse and offering clean and affordable water solutions. SBIR project funding is enabling the transition of this promising membrane technology from the laboratory setting into the early commercialization stages of a valuable new product.This SBIR Phase I project proposes to improve the commercial viability of novel nanofiltration membranes through the development of more-scalable and tunable synthesis and manufacturing protocols. The technology is based on self-assembling block copolymers with customizable chemical functionalities. Previous methods for the synthesis and casting of the polymers are not ideal, so new protocols are being developed. The changes to polymer and membrane manufacturing methods will be conducted systematically to develop new structure-property-performance relationships that will contribute new knowledge for broader membrane optimization efforts. A more thorough understanding of how polymer chemistry dictates membrane performance will also be cultivated by investing in the customization aspects of the technology. Finally, the performance characteristics of resulting nanofiltration membranes will be rigorously tested with respect to permeability, chlorine-resistance, separations, and heavy metal capture. The overall results will help advance nanofiltration membrane technology into a platform that is highly modular and can address a wider range of separations challenges than is currently possible.