(644f) Highly Interconnected Pores in Hybrid Nanofilms for Ultrafast Solvent Transport with Precise Molecular Separation

Materials with rigid, precisely controlled nanopores that are within 1 nm and stable in harsh conditions have potential to be fabricated into membranes for organic solvent nanofiltration (OSN). To achieve high permeance through these membranes, the traditional route is to reduce the selective layer thickness and thus lower the transport resistance. Although membranes as thin as one atom have been prepared, this thinness often challenges the membrane’s potential for defect free scale-up. Another route, often overlooked, is to increase the pore interconnectivity of the membrane material, described by the ratio of porosity and tortuosity (ε/τ), which greatly influences the transport through a membrane. In this work, we fabricated membranes using a hybrid nanofilm with highly interconnected pores, with ε/τ of ~ 0.2, almost doubling that of the current OSN membranes, and obtained methanol permeance as high as 267 L m^-2 h^-1 bar^-1, > 2.5 times higher than the reported membranes with similar molecular weight cut-off (MWCO). Precise tuning of MWCO in the range of 200-1,000 Da with a step change as small as approximately 100 Da was realized by adjusting the membrane synthesis and calcination conditions. Molecular dynamics (MD) simulation shows the formation of nanometer-sized pores in hybrid material, while pore size and interconnectivity were realized as a function of the calcination conditions. These membranes have rigid pores that are stable in various organic solvents and at elevated temperatures, ensuring stable molecular separation under challenging industrial conditions.