The objective of this dissertation is to obtain a better understanding of how the molecular level properties of ionic liquids and poly(ionic liquids) effect the transport of solutes within the compounds. This knowledge is especially useful in regard to light gas separations, such as CO2/N2 and CO2/CH4. As was found in our research, the vast sea of potential ILs can by narrowed down considerably by using molecular dynamics simulations such as COSMOTherm. Once potentially useful cation/anion combinations are determined, laboratory synthesis and experimentation can verify whether the materials can be used as successful membranes. Additionally, this work shows how rearrangement of the conformation of sub-groups on the cation can vastly change its permeability and selectivity performance. Finally, this work also addresses a void in the literature regarding poly(IL) bulk-material studies. We show that poly(IL) materials have the potential to be superabsorbent materials, due to the behavior of the cation and anion when subjected to polar organic solvents.