Enhancing gas permeation and separation performance of polymeric membrane by incorporating hollow polyamide nanoparticles with dense shell

Many inorganic nanofillers including porous nanoparticles and nonporous nanoparticles, are incorporated into the polymer matrices to exceed the trade-off relationship between the gas permeability and the permselectivity of the polymeric membrane materials. However, the organic-inorganic combination often suffers from the undesirable interface between the organic matrices and the inorganic fillers. In this study, we fabricated the hollow polyamide nanoparticles with dense shell via the interfacial polymerization in the surfactant-free microemulsion. And then the hollow nanoparticles combined with liquid acrylate monomers to form the mixed matrix membranes (MMMs) via the UV-induced photo-polymerization. The nanoparticles with an average diameter of 42 nm dispersed uniformly in the membranes. The resulting membranes showed no obvious defect. Compared with those of the pure polymer membrane, the CO(2 )permeability and CO2/N-2 permselectivity of the MMMs both increased as the nanofiller loading increased. And the gas permeation and separation performance exceeded the Robeson upper bound line with a maximum CO2 permeability of 1898 Barrer and a maximum CO2/N-2 permselectivity of 43.9 at 1 wt% nanofiller loading. The improvement mainly arose from the increase in the CO2 solubility, the N-2 diffusivity and the CO2/N-2 solubility selectivity. This combination of the hollow polymer nanoparticle with the dense shell and the polymeric membrane is also promising for fabricating ultra-thin and defect-free membranes for gas separation.