Macroscopic samples of polystyrene with ordered three-dimensional nanochannels.

Abstract

Block copolymers containing a chemically degradable block are versatile precursors to nanoporous organic materials. Most work in this area has been accomplished in thin films. However, high surface area catalysis, separations, and nanotemplating can require monolithic samples with macroscopic pore volumes. Only a few examples of monolithic nanoporous materials from ordered block copolymers have been reported. In nearly all of these cases, the materials contain parallel cylindrical pores templated from the commonly observed hexagonally packed cylindrical (C) morphology adopted by AB diblock copolymers. To significantly expand the potential utility of this class of materials, we have targeted the bicontinuous gyroid (G) morphology in polystyrene block copolymers containing a degradable component. In this communication we describe the preparation of macroscopic samples of polystyrene with ordered three-dimensional nanochannels using either a polystyrene-polylactide (PS-PLA) block copolymer or a polystyrene-poly(ethylene oxide) (PS-PEO) block copolymer that adopts the G morphology. In addition, we show that a blend of these two materials also adopts the G morphology and that selective removal of the polylactide phase leaves a nanoporous material with poly(ethylene oxide)-lined pore walls that render the material water wettable.