title: Amphiphilic Graft Copolymer Nanospheres: From Colloidal Self-Assembly to CO2 Capture Membranes.
abstract: Colloidal nanosphere self-assembly effectively generates ordered nanostructures, prompting tremendous interest in many applications such as photonic crystals and templates for inverse opal fabrication. Here we report the self-assembly of low-cost, graft copolymer nanospheres for CO2 capture membranes. Specifically, poly(dimethylsiloxane)-graft-poly(4-vinylpyridine) (PDMS-g-P4VP) is synthesized via one-pot, free radical dispersion polymerization to give discrete monodisperse nanospheres. These nanospheres comprise a surface-anchored highly permeable PDMS layer and internal CO2-philic P4VP spherical core. Their diameter is controllable below the submicrometer range by varying grafting ratios. The colloidal dispersion forms a long-range, close-packed hexagonal array on a substrate by inclined deposition and convective assembly. The array shows dispersion medium-dependent packing characteristics. A thermodynamic correlation is determined using different solvents to obtain stable PDMS-g-P4VP dispersions and interpreted in terms of Flory-Huggins interaction parameter. As a proof-of-concept, the implementation of these nanospheres into membranes simultaneously enhances the CO2 permeability and CO2/N2 selectivity of PDMS-based transport matrixes. Upon physical aging of the solution, the CO2/N2 selectivity is improved up to 26, one of the highest values for highly permeable PDMS-based polymeric membranes.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea.
authors.forename: Harim
authors.initials: H
authors.lastname: Jeon
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea.
authors.forename: Dong Jun
authors.initials: DJ
authors.lastname: Kim
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea.
authors.forename: Min Su
authors.initials: MS
authors.lastname: Park
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea.
authors.forename: Du Yeol
authors.initials: du Y
authors.lastname: Ryu
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea.
authors.forename: Jong Hak
authors.initials: JH
authors.lastname: Kim
keywords: CO2 capture; colloidal nanosphere; graft copolymer; membrane; self-assembly