Composite membranes with ultrathin and conformal passivation for universal microfiltration compatible with organic solvents

The development of porous membranes with excellent solvent resistances is an important technical task in relation to environmental and energy issues, including chemical waste treatment in the semiconductor industry. However, common polymer membranes, except for Teflon-based membranes, do not guarantee universal resistance to various organic solvents. In this study, a universal strategy is proposed to improve the solvent resistances of polymeric porous membranes through conformal passivation of ultrathin metal oxide layers via atomic layer deposition. Conformal ZnO shells with a thickness below ~62 nm can significantly improve the inherently low resistances of nitrocellulose, polyethersulfone, and polycarbonate membranes to organic solvents without significantly degrading the flux. Although the polymer core is gradually dissolved by the organic solvent penetrating through the native cracks of the ZnO shell as the time of exposure to the organic solvent increases, the rigid porous network composed of hollow ZnO can well maintain its monolithic form for more than 1 week. Thus, it is possible to effectively filter pollen grains and heavy metal microparticles dispersed in harsh organic solvents without expensive Teflon-based membranes. This study opens new opportunities for selection of organic solvent-compatible membranes for microfiltration.

Automated summary

Improving the solvent resistances of polymeric porous membranes by atomic layer deposition can effectively filter pollen grains and heavy metal microparticles in organic solvents.