Polymer-Grafted Porous Silica Nanoparticles with Enhanced CO2 Permeability and Mechanical Performance

Three different types of polymer ligands, poly(methyl methacrylate) (PMMA), poly(methyl methacrylate-random-poly(ethylene glycol)methyl ether methacrylate) (PMMA-r-PEGMEMA), and poly(ionic liquid)s (PIL), were grafted onto the surface of 15 nm solid and large hollow porous silica nanoparticles (average particle size similar to 60 nm) by surface-initiated atom transfer radical polymerization (SI-ATRP) to demonstrate the enhanced carbon dioxide (CO2) permeability as well as mechanical properties. After characterizing the purified products, free-standing bulk films were fabricated by the solvent-casting method. The poly(ionic liquid) nanocomposite films exhibited a much higher carbon dioxide permeance than PMMA and PMMA-r-PEGMEMA systems with a similar silica content. Also, the hollow silica-mixed matrix membranes showed a significant enhancement in CO2 permeability compared to the 15 nm solid silica films because of the pore structure. Despite the transparency loss due to the scattering of larger particle sizes, the hollow silica particle brush films exhibited the same mechanical properties as the 15 nm solid silica-derived ones.

Automated summary

This study demonstrated the enhanced carbon dioxide permeability and mechanical properties by grafting three different types of polymer ligands onto the surface of solid and large porous silica nanoparticles through surface-initiated atom transfer radical polymerization. The poly(ionic liquid) nanocomposite films showed higher carbon dioxide permeance compared to other systems, while the hollow silica-mixed matrix membranes exhibited significant enhancement in CO2 permeability due to their pore structure. Despite the loss of transparency, the hollow silica particle brush films maintained similar mechanical properties to the solid silica-derived films.