Introducing Chemical Transport Selectivity into Gold Nanotubule Membranes

Abstract

Abstract : We recently described polymeric membranes that contain a collection of monodisperse Au nanotubules with inside diameters of molecular dimensions (<1 nm). W showed that these membranes can be used to cleanly separate small molecules on the basis of molecular size. These membranes can also show charge-based transport selectivity which can be reversible switched between cation and anion-selective states. In addition to molecular size- and charge-based selectivity, chemical interactions (e.g., hydrogen bonding or hydrophobic interactions) between the membrane material and the molecule to be transport can be used to control transport selectivity. The introduction of such chemically-based transport selectivity into the Au nanotubule membranes is described here. This was accomplished by chemisorbing thiols (R-SH) to the Au tubule surfaces. Membranes derivatized with two different R groups - the hydrophobic R = -C16H33 and the more hydrophilic R = -C2H4-OH - were prepared. We show here that the rate and selectivity of transport in these membranes is dramatically altered by the chemical identity of the R group.