In this dissertation, the development of a new membrane technology that can be utilized as a template for separation devices in a broad variety of fields is discussed. In general, membranes are implemented in processes to act as semi-permeable separators, allowing particles to pass through at different rates, thus effecting a separation. However, many currently used membranes are limited by either their selectivity for one particle over another or their permeability. Previous research has demonstrated the ability to cast block polymers into membranes with self-assembled nanostructures making them efficient size-selective separators that are both highly permeable and selective. The research presented here builds further upon these materials, changing the chemistry of one of the functional blocks to allow the membranes to act as functionalizable platforms that can be chemically tailored for directed applications. The material demonstrated the ability to self-assemble into nanopores, and after hydrolysis, carried out separations that set new limits for block polymer membranes. By performance testing in affinity-based separations, the membrane displayed high uptake capacities, sharp breakthrough, and good selectivity of divalent ions in water. These membranes offer further versatility in their ability to be chemically-modified to incorporate a variety of small molecules into the pore walls. The efficient removal of heavy metal ions shows the applicability to critical separations needed in our society today. Even further, the establishment of the functionalizable self-assembled membrane lays the groundwork for countless opportunities in future separations yet to be developed.