Pore structure of the polyethyleneimine/SBA-15 nanocomposites studied by positron annihilation lifetime spectroscopy

Pore structure of Polyethyleneimine (PEI)/SBA-15 nanocomposites was investigated by Positron Annihilation Lifetime Spectroscopy (PALS) in conjunction with other conventional means like TEM , XRD and N 2 adsorption and desorption techniques. In this study, PALS could help us obtain the information of micropores and mesopores in the SBA-15 matrix at same time via analyzing the change of long lifetime components τ 3 and τ 4 . The size of micropores and mesopores could be obtained based on theoretical models, which is slightly smaller than the mesopore size obtained by N 2 adsorption and desorption techniques due to the existence of open micropores in the channel. This provides unique tool for understanding the evolution of the nanometer-sized pores in SBA-15 and PEI/SBA-15 composites and quantitative description of the relationship between the materials structure and its CO 2 adsorption capacity in the future.