Hierarchical Pore Structures and High ZIF-8 Loading on Matrimid Electrospun Fibers by Additive Removal from a Blended Polymer Precursor

A novel method for increasing the effective nanoparticle loading in electrospun fibers is presented involving the electrospinning of polymer blends with suspended ZIF-8 crystals. Initially, varying ratios of Matrimid 5218 and poly(ethylene oxide) (PEO) are electrospun, followed by methanol washes to remove PEO to form porous Matrimid nanofibers. After an optimum surface area is found from the ratio of 1:1 Matrimid:PEO by weight, the metal-organic-framework ZIF-8 is suspended in the polymer blend and electrospun to form ZIF-8 impregnated fibers. After PEO removal from ZIF-8 impregnated fibers, it is found that the ZIF-8 remains in the porous fibers, resulting in drastic increases in ZIF-8:nanofiber loadings, increased gas uptake, and increased accessible ZIF-8 within the fibers. This method is anticipated to work for many different nanoparticle-polymer systems, having implications in the fields of filtration, sensing, catalysis, and adsorption.