Synthesis, structure and gas separation properties of ethanol-soluble, amphiphilic POM-PBHP comb copolymers

K Kim and DA Kang and JT Park and KC Kim and JH Kim, POLYMER, 180, UNSP 121700 (2019).

DOI: 10.1016/j.polymer.2019.121700

We report the synthesis of a series of alcohol-soluble comb copolymers, specifically poly(oxyethylene methacrylate)-co- poly(2-(4-benzoyl-3-hydroxy phenoxy) ethyl acrylate) (POM-PBHP), with various compositions, as well as their use in CO2 capture membranes. The POM-PBHP comb copolymers were synthesized through a low-cost free- radical polymerization method and analyzed based on Fourier transform infrared spectroscopy and nuclear magnetic resonance. The interactions and structures of the comb copolymers were characterized via Xray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The comb copolymers showed good solubility in volatile nontoxic ethanol, allowing them to be coated onto microporous polymer supports to form thin-film composite membranes. While both neat POM and PBHP membranes showed very poor separation properties, the POM-PBHP comb copolymers were effective at separating CO2 from N-2. This is because the POM chains with ether oxygen groups have a strong affinity for CO2, leading to high CO2 permeance, whereas the rigid PBHP chains with aromatic rings hinder N-2 permeance based on reduced chain mobility. All the full-atomistic molecular dynamics simulations based on density functional theory were also used to characterize the molecular structure and binding energy for CO2, which is consistent with the experimental results. The performance of the membranes was greatest when the content of PBHP in the copolymer was 15 wt%. The CO2/N-2 selectivity and CO2 permeability reached 46.6 and 111 Barrer, respectively, which represents one of the highest values for alcohol-soluble, additive-free polymeric membranes and is similar to that of commercial PEBAX membrane.

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