Liquidlike nanoparticle organic hybrid materials (NOHMs) were designed and synthesized by ionic grafting of polymer chains onto nanoscale silica units called polyhedral oligomeric silsesquioxane (POSS). The properties of these POSS-based NOHMs relevant to CO2 capture, in particular thermal stability, swelling, viscosity, as well as their interactions with CO 2, were investigated using thermogravimetric analyses, differential scanning calorimetry, and NMR and ATR FT-IR spectroscopies. The results indicate that POSS units significantly enhance the thermal stability of the hybrid materials, and their porous nature also contributes to the overall CO 2 capture capacity of NOHMs. The viscosity of the synthesized NOHMs was comparable to those reported for ionic liquids, and rapidly decreased as the temperature increased. The sorption of CO2 in POSS-based NOHMs also reduced their viscosities. The swelling behavior of POSS-based NOHMs was similar to that of previously studied nanoparticle-based NOHMs, and this generally resulted in less volume increase in NOHMs compared to their corresponding polymers for the same amount of CO2 loading. © 2013 American Chemical Society.