Porous nano- and microfibrous polymeric membrane material for catalytic support

High surface area is essential for attachment of functional groups, ions, moieties and nanoparticles. Surface area of fibrous membrane can be enhanced by reducing the fiber diameter or producing the porous fibers. Flow properties of the fibrous membrane can be improved by placing the fibers apart in the fibrous network. By electrospinning, it is feasible to produce the fibrous membrane of specific surface area and Darcy permeability higher than 60 m2/g and 1 × 10−11 m2, respectively. The interconnected irregular shape mesopores (2–50 nm) within the fibers increase the accessible surface area. On the other hand, presence of macropores (pores larger than 50 nm) largely increases the pore volume (porosity) in fibers and helps to reduce the diffusion resistances. Beaded fibers in the membrane can be used to reduce the bulk transport resistances. We developed a method for incorporating the mesopores and macropores in the nano/microfibers made of engineering plastics. To achieve ∼60 m2/g specific surface area by reducing the fiber diameter, one needs to draw the fibers down to 50–60 nm. In present study, 60 m2/g of specific surface area is achieved through the porous fibers of average diameter of 900 nm. A specific surface area result from the porous fiber is much higher than one can achieve by reducing the diameter of fibers.

Research highlights▶ We developed a method for incorporating the mesopores and macropores in the nano/microfibers made of engineering plastics. The produced nano and microfibrous membrane materials have several unique properties such as high surface area, flexibility, superior directional strength, good interconnectivity of pores, good transport properties and potential to incorporate the active chemistry or functionality on nanoscale. ▶ The interconnected irregular shape mesopores (2–50 nm) within the fibers increase the accessible surface area. On the other hand, presence of macropores (pores larger than 50 nm) largely increases the pore volume (porosity) in fibers and helps to reduce the diffusion resistances. Beaded fibers in the membrane were used to improve the bulk transport properties. The bulk transport properties of the fibrous membrane can also be improved by placing the fibers apart in the fibrous network. ▶ By electrospinning, it was feasible to produce the fibrous membrane of specific surface area and Darcy permeability higher than 50 m2/g and 1 × 10−11 m2, respectively.