Synthesis of polyurea network/silica nanoparticle composites with hierarchical porosity for carbon dioxide adsorption

Abstract

Polyurea network/silica nanoparticle composites with hierarchical porosity and shape processability are synthesized for carbon dioxide adsorption. Polyurea network(UN) is synthesized by polymerizing tetrakis(4-aminophenyl)methane (TAPM) and hexamethylene diisocyanate (HDI) as an organic sol. Silica nanoparticles (SNPs) are functionalized with (3-aminopropyl)triethoxysilane(APTES) and react with UN sol. It is heated at 380 ℃, by which micropores are developed through rearrangement of urea bonds and vaporization of volatile fragments. SNPs are covered with RUN and macropores are developed by aggregation of SNPs covered RUN.

In comparison with the pristine RUN, RUN of RUN/SNPs composite showed high CO₂ adsorption capacity, achieving 3.0 mmol g-1 at 25 ℃ and 1 atm. The high CO₂ adsorption capacity is most likely due to the increase of open adsorption site which was produced by prevention RUN collapse and development of macropores. Moreover, RUN/SNPs composite exhibited maintenance of CO2 adsorption capacity after molding while CO2 adsorption capacity of RUN reduced after molding. RUN/SNPs are promising materials for indoor CO₂ capture due to their molding property.