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.