Nanostructures Functionalized Poly (Ionic Liquid)s For Carbon Dioxide Adsorption

Anthropogenic CO₂ emission,especially from fossil fuel combustion,is the main reason leading to greenhouse gas emission as well as global warming.CO₂ capture and storage is considered as a direct and effective way to mitigate environmental issues induced by CO₂ emissions.Therefore,it is of critical significance to develop an effective and economic technology as well as the corresponding sorbent materials with promising capacity for capturing CO₂.Amine-functionalized solid sorbents have attracted great attention in of the developed solid sorbents.Immobilization of amine onto porous solid matrices shows promising CO₂ adsorption capacity,good cycling stability,and high selectivity.Because of the existed surface hydroxyl groups and high surface area facilitating surface modification,titanate nanotubes（TiNTs）have been the suitable choice as solid matrix of solid sorbents.Moreover,the three-dimensional cage structure of POSS-MA has provided a new idea for preparing composite materials.The unique properties of Ionic liquids（ILs）such as non-volatile,good stability and tunable physicochemical characteristics have made them excellent materials for CO₂ adsorption.Moreover,since poly（ionic liquid）s（PILs）exhibit not only the inherent characteristics of ILs but also the common properties of polymer architecture,they have been realized as efficient sorbents for CO₂ adsorption.In this thesis,a simape radical polymerization process（grafting through）has been developed to synthesize amino-functional poly（ionic liquid）s brushes on TiNTs and nanostructures functional composite materials POSS-PVIM.It is expected that the synthesized organic-inorganic nano-composite materials can take the advantages of the space structure for adsorption and PILs for adsorption and absorption,and hold promising sorption capacity under CO₂ partial pressure of 0.2 bar.Based on the structural characterization of the synthesized composite materials,and CO₂adsorption performance of different materials synthesized under different polymerization conditions,some conclusions are summarized as follows:（1）The TiNTs synthesized by hydrothermal process are proved to have rich hydroxyl groups and high surface area,which makes it suitable for preparation of PILs brushes as solid matrix.In addition,through the characterization of methacrylate modified TiNTs,a high grafting rate of 18.35%is reached.（2）Amine-functionalized PILs brushes have been successfully synthesized through the“grafting through”process as evidenced by various techniques.Particulalrly,TGA-DSC results demonstrate that PILs brushes have polymer loading of 60%and possess good thermal stability under 300℃,which make it available for high temperature cycle test.（3）With increasing polymerization time,the CO₂ adsorption capacity of PILs brushes increased.With the increase in monomer concentration,the CO₂ adsorption capacity increase until reach the maximum value,followed by decrease in adsorption capacity.Under polymerization time of 3h,monomer concentration of 20%and initiator concentration of 2%,the PILs brushes show the best CO₂ adsorption capacity of 0.738mmol/g under CO₂ partial pressure of 0.2 bar,much higher than that of free polymer（0.298 mmol/g）and that of TiNTs（0.059mmol/g）,which proves that grafting can improve CO₂ adsorption performance effectively.（4）Preliminary experiment is designed and nanostructures functional composite materials（POSS-PVIM）arethensuccessfullysynthesizedusing methacrylate-functionalized POSS.As a result,low crosslinking degree of POSS-PVIM samples show better adsorption capacity of 0.315mmol/g than samples with high crosslinking degree.By comparison of the synthesized two kinds of composite materials,the CO₂ adsorption capacity of PILs brushes is better than POSS-PVIM composite materials,attributed to the difference in pore structure and pore volume.Both kinds of nanostructure composite materials appear deactivation of amino groups in reversibility tests,but it remains a relatively stable cycling performance.