Synthesis of Poly(ionic Liquid)s--poly(methyl Methacrylate) Copolymer-Grafted Silica Particle Brushes with Enhanced CO Permeability and Mechanical Performance.

Poly(ionic liquid) (PIL)-based block copolymers are of particular interest as they combine the specific properties of PILs with the self-assembling behaviors of block copolymers, broadening the range of potential applications for PIL-based materials. In this work, three particle brushes: SiO--poly(methyl methacrylate) (PMMA), SiO--PIL, and SiO--PMMA--PIL were prepared through surface-initiated atom transfer radical polymerization. Unlike the homogeneous homopolymer particle brushes, the block copolymer particle brush SiO--PMMA--PIL exhibited a bimodal chain architecture and unique phase-separated morphology, which were confirmed by size-exclusion chromatography and transmission electron microscopy. In addition, the influence of the introduction of the PMMA segment on the gas separation and mechanical performance of the PIL-containing block copolymer particle brushes were investigated. A significant improvement of Young's modulus was observed in the SiO--PMMA--PIL compared to the SiO--PIL bulk films; meanwhile, their gas separation performances (CO permeability and CO/N selectivity) were the same, which demonstrates the possibility of improving the mechanical properties of PIL-based particle brushes without compromising their gas separation performance.