(380aa) Fabrication and Evaluation of Polyetherimide Membranes Containing Pluronic P-123 and Graphene Using Vapor-Induced Phase Separation

Membrane-based separation systems are essential in various industries, such as water and gas treatment, drug delivery, and biological processes. A membrane's effectiveness often relies on the structure of its principal separation or active layer. Vapor-induced phase separation (VIPS) is a method that uses a vapor, usually water vapor, to induce phase inversion in a membrane casting solution. Unlike the more common nonsolvent-induced phase separation (NIPS) process for making asymmetric polymeric membranes, mass transfer in VIPS is slower, allowing for more precise control over casting parameters and the resultant membrane morphology. VIPS can create ultra-small pores ranging from 20 to 100 nm; however, adjusting VIPS parameters can lead to a variety of pore sizes and membrane structures ranging from asymmetric cellular to symmetric nodular and sponge-like morphologies. In this study, we examined how key parameters in VIPS affect the structure and performance of Polyetherimide (PEI) membranes. These parameters include the concentration of the Pluronic P-123 as the pore-forming agent, relative humidity (RH), vapor exposure time, and the presence of Graphene as an effective additive. A casting solution containing a PEI concentration of 17 wt. % at a dissolution temperature of 65 ˚C and a vapor temperature of 50 ˚C was used in this study. The pore-forming agent concentrations ranged from 1 to 3 wt.% while RH varied from 40 to 90%. Vapor exposure times ranged from 0 (NIPS process) to 1 hour. The pore-forming agent used was an amphiphilic block copolymer, Pluronic P-123. We hypothesized that the hydrophobic segments of Pluronic P-123 anchor in the polymer matrix, while the hydrophilic segments extend outwards, enhancing membrane surface hydrophilicity and anti-fouling properties. Measurements of pure water flux (PWF) showed that increasing RH from 40 to 90 improves PWF from 4.73 to 14.72 L.m^-2.h^-1, respectively at a constant exposure time of 15 minutes and pore-forming agent concentration of 1 wt.%. On the other hand, increasing exposure time has the opposite effect. Ranging the exposure time from 15 minutes to 1 hour leaded to a decrease in PWF from 6.26 to 4.91 L.m^-2.h^-1, respectively at a constant RH of 65% and pore-forming agent concentration of 1 wt.%. Future work will explore the impact of adding different amounts of graphene as an additive on the structure and performance of membranes produced using the VIPS process. This research contributes to our understanding of the structure and properties of PEI membranes, potentially improving their efficiency in ultrafiltration applications.