Thermal stability, swelling behavior and CO₂ absorption properties of Nanoscale Ionic Materials (NIMs)

Abstract

Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO 2 capture material. To optimize NIMs for CO 2 capture, their structureproperty relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally-and CO 2 -induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally-and CO 2 -induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies.It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO 2 compared to their corresponding polymers.

Recent Advances in Anhydrous Solvents for CO2 Capture: Ionic Liquids, Switchable Solvents, and Nanoparticle Organic Hybrid Materials

“…Like ILs, NOHMs exhibit negligible vapor pressure owing to the bond existing between the canopy (or canopy plus corona) and the thermostable nanocore. The latter feature also confers NOHMs with a good thermal stability up to about 300°C, which is always higher than the parent polymer (Lin et al, 2014). Currently, NOHMs are classified based on their representative phase and synthesis methods as well as the existence of task-specific functional groups (see Scheme 5B) (Lin and Park, 2011).…”

Nanoscale Hybrid Electrolytes with Viscosity Controlled Using Ionic Stimulus for Electrochemical Energy Conversion and Storage

“…NOHMs boast a high degree of chemical and physical tunability, with a wide range of nanocore–canopy combinations possible for a variety of functionalities. They exhibit negligible vapor pressure and a higher thermal and oxidative stability compared to those of their constituent polymers. − NOHMs were initially developed by Archer et al as electrolyte additives to suppress dendritic growth in battery applications − and were explored by Park et al as anhydrous CO 2 capture solvents. − ,− The synthesis, dynamics, and CO 2 capture mechanisms of various classes of NOHMs have been extensively investigated. − ,− NOHMs interact with other chemical species based both on enthalpic and entropic contributions, which are influenced by the functional groups along the polymer chains and the structural configurations of the NOHMs’ polymeric canopy, respectively . Recently, NOHM-based fluids have been explored as potential novel electrolytes in electrochemical applications and for combined CO 2 capture and conversion , based on their ability to complex redox-active species and selectively capture CO 2 .…”

Localized and Collective Dynamics in Liquid-like Polyethylenimine-Based Nanoparticle Organic Hybrid Materials

“…There is no doubt therefore that the extent to which NOHMs can be engineered to meet specific requirements depends on in-depth understanding of the role played by each of their structural components in determining the overall properties. Among the applications for which NOHMs are outstanding as potential candidates is their use as novel solvents for gas separations, particularly CO 2 capture. − ,− Since they are chemically and thermally stable and possess negligible vapor pressure with high degrees of chemical and physical tunability, they are promising for a wide range of reactive and separation systems. NOHMs have been found to interact with gas molecules and ionic species based on enthalpic contributions, which arise from the functional groups along the tethered polymeric chains as well as entropic contributions, which are driven by the structural configurations of the polymeric canopy .…”