High flux CO2 transporting nanochannel fabricated by the self-assembly of a linear-brush block copolymer

Abstract

Linear-brush poly(styrene)-b-poly[oligo(ethylene glycol) methyl ether methacrylate] (PS-b-POEGMA) block copolymer incorporating a UV-crosslinkable coumarin group in a PS block, self-assembled into a cylindrical structure with POEGMA cylinders perpendicular to the film surface, which exhibit excellent CO2 separation properties. The block copolymer was successfully synthesized by a combination of atom transfer radical polymerization (ATRP) and click chemistry. The molecular characterization of the diblock copolymer was performed with 1H nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The cylindrical phase structure was confirmed by small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The POEGMA amorphous phase was confirmed by differential scanning calorimeter (DSC). Gas permeation properties of CO2, N2 and He were determined around room temperature. Compared to the linear BCP, the total gas selectivity and especially CO2 permeation flux increased dramatically. The functional block units and self-assembled microphase structures synergetically played key roles in the high performance of the membrane.