Ordered nanoporous cellulose-based membranes fabricated via breath figure method for copper ion detection†

Abstract

Ordered nanoporous membranes with uniform pore sizes have been widely used in various fields due to their excellent performance. The breath figure method offers a simple and controllable approach to preparing ordered porous membranes, but fabricating membranes with nanoscale pore sizes remains challenging. In this work, ethyl cellulose grafted polystyrene is synthesized via ethylation and atom transfer radical polymerization reactions. The effect of the polymer solution's spreading degree during the breath figure process on pore morphology is investigated. The obtained membranes exhibit an ordered nanoporous structure with an average minimum pore size down to 33 nm, which is the smallest pore size reported using the breath figure method. These nanoporous membranes demonstrate certain ion selectivity. Additionally, after adsorbing a large amount of bovine serum albumin, these membranes can be used for high-sensitivity detection of Cu²⁺ concentrations in aqueous solution, with a detection limit as low as 10⁻¹⁶ M.