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

Hybrid materials, especially in the polymer field, have drawn the attention of many researchers as they enable the combination of properties of their organic and inorganic components to improve physical and chemical properties. 4 Nanoparticle organic hybrid materials (NOHMs) represent one of the new classes of such materials 21 that consist of polymer chains (canopy) grafted onto an inorganic nanoparticle (core), with or without the use of linkers (corona). Depending on the type of the NOHMs, the link between the canopy and the corona is covalent or ionic. In the latter case, the NOHMs have also been referred to as nanoscale ionic materials (NIMs). 14,16 A wide range of materials including oxides (Fe2O3, SiO2, TiO2, ZnO), metals (Au, Pd, Pt, Rh), and polyoxometalates can be employed as the cores, while the corona usually corresponds to a silane or thiol compound. 14,16 20 The selection of the polymeric canopy materials is also extensive. The interest in these hybrid materials for energy and environmental-related applications is fostered by their tunable nature for specific physical and chemical properties that can be achieved via the variation of the core size, core fraction, and canopy length and via the selection of polymers with different functional groups. The NOHMs can be synthesized as solid-like, gel-like, and liquid-like materials depending on their applications. An important characteristic of the liquidlike class of the NOHMs, which distinguishes them from conventional functionalized nanoparticles, is the retention of the liquid state in the absence of solvent. This is because the polymer chains from the canopy act as the solvating medium. Although still at an early stage, the applications of liquid-like NOHMs have been proposed in various areas such as lubricants, water desalinization, optics and photonics, electrolytes, magnetic fluids, and CO2 capture. 12,19,20