Spectroscopic Investigation of the Canopy Configurations in Nanoparticle Organic Hybrid Materials of Various Grafting Densities during CO2 Capture

Novel liquid-like nanoparticle organic hybrid materials (NOHMs) made of polyetheramine chains tethered onto functionalized silica nanoparticles were synthesized and characterized before and after exposure to CO2 using NMR, Raman, and ATR FT-IR spectroscopies in order to investigate the effect of the grafting densities on the NORM canopy structure. Considering the promising tunable properties for CO2 capture of NOHMs, this study was conducted to provide important structural information to better design NOHMs for CO2 capture. In order to minimize the CO2 absorption via enthalpic effect and provide a more accurate assessment of the structural effects, the NOHMs were synthesized without task-specific groups. A greater chain ordering and decreased intermolecular interactions were observed in NOHMs compared to the unbound polymer. This was attributed to the specific structural arrangement of the frustrated canopy. The distinct configuration of grafted polymer chains caused different CO2 packing and CO2-induced swelling behaviors between the NOHMs and the unbound polymer. The grafting density influenced the ordering and coupling of the polymer chains and CO2-induced swelling. Its effect on the CO2 packing behavior was less pronounced.