2025 AIChE Annual Meeting

(401y) Amphiphilic Polyelectrolyte Complexes As High Permeance Organics Selective Bilayer Membranes

Authors

Luca Mazzaferro, Tufts University
Jeffrey McCutcheon, University of Connecticut
Ayse Asatekin, Tufts University
Membranes are efficient, scalable, and simple to operate. However, traditional membranes often exhibit limited selectivity and propensity to fouling. Their long-term chemical and physical stability are also limited. The ability of functional polymers to self-assemble provides a basis for creating membranes that can perform novel and effective separations with high selectivity control. This work introduces a high- performance thin film composite (TFC) membrane fabricated with Amphiphilic PolyElectrolyte Complexes (APEC) as a new family of self-assembling polymer selective layers with high organics selectivity. Amphiphilic PolyElectrolytes (APEs) are random copolymers that combine hydrophobic and charged monomers and are water-insoluble. Cationic and anionic APEs are consecutively rod-coated over a substrate to create a bilayer TFC membrane. At the interface, APEs self-assemble into the complex form (APEC) due to interactions between opposite charged functional groups in two APE layers. This creates tight nano-sized ionic domains, acting as selective channels with tunable selectivity within a hydrophobic matrix which produces TFC membranes with organics rejection in nanofiltration range coupled with high permeability. To date, only one APEC chemistry has been studied. Here we explore how the effective pore size, selectivity, and capabilities of the membranes can be tuned by changing the chemical structures of hydrophobic and charged monomers forming the APEs. Preliminary results indicate that the resulting bilayer's selectivity differs significantly from that of each layer alone, showing high water permeance and stable much tighter pore sizes, with high small organics and comparatively lower monovalent salts rejections. We expect that this arises from a combination of changes in charge and pore size due to the interaction between the two APEs at the interface of the two layers which creates tighter pores that control permeation. Having high neutral solutes and low salts rejections is beneficial for many applications. A simple and scalable method of synthesis and membrane manufacturing was used with diverse potential chemical functionalities which offers versatility and potential for creating membranes with targeted selectivity to address separations of need like water treatment applications and complex separations. The manufacturing of APEC membranes using electrospray coating method is also investigated to show versatile and customizable methods for developing new high-performance membranes.