Abstract: Making membranes through additive manufacturing (i.e. ​“3D printing”) has emerged as a popular field of study in membrane science over the past half-decade. Additive manufacturing confers a number of benefits when making membranes including customizability, thickness control, morphology control, and hierarchical design. Alternative manufacturing techniques also enable the processing of emergent materials into high performance membranes. This is important because while the number of new materials in membranes has increased dramatically, the options for processing those new materials has not. 

Our work has identified a new approach to making membranes through additive manufacturing using electrospray deposition. This method enables the processing of classic and emerging polymer materials into thin film composite (TFC) membranes. Unlike current TFC membranes, we do not need to form these selective layers in-situ. In fact, our work demonstrates the ability to print membranes for a variety of separations using a number of emergent materials, such as zwitterionic copolymer (nanofiltration), polyether epoxy (chlorine tolerant nanofiltration), and PIM-1 (gas separations). Traditionally, these polymers would be processed using a phase inversion process, leading to an integrated asymmetric membrane with relatively low permeance. Our work demonstrates the versatility of the method to make TFC membranes with different polymers and yield selective yet substantially higher permeance due to our ability to make thinner, defect free membranes. We contextualize this work in the broader perspective of membrane manufacturing, which has seen little innovation in the past 4 decades. Innovations in membrane manufacturing will enable the use of the increasing number of new membrane materials and could help realize the benefits promised by these materials.