Study on the mechanism of regulating the pore structure of MCF by polyethyleneimine modification

A novel mesoporous silica foam (MCF) with a specific surface area of 712.5 m<sup>2</sup>/g and pore volume 2.44 cm<sup>3</sup>/g was synthesized by using triblock copolymer poly (ethylene oxide, polypropylene oxide ethylene P123) as template TEOS (C<sub>8</sub>H<sub>20</sub>O<sub>4</sub>Si) silicon source. The effect polyethylenimide (PEI) modified MCF on nanoscale structure studied positron annihilation lifetime spectroscopy (PALS) conventional characterization methods, such N<sub>2</sub> adsorption desorption, transmission electron microscopy, thermogravimetric analysis Fourier transform infrared spectroscopy. results show that the has an obvious disordered structure, continuous porous network window connection between pores is formed. Meanwhile, it can be seen directly PEI been successfully introduced into channels. In order to evaluate size its distribution more comprehensively, mechanism which highly sensitive nanometer scale open volumes in loaded were studied. It found there are two long life components τ<sub>3</sub> τ<sub>4</sub>, indicating coexistence micropores mesopores samples. Furthermore, introduction molecules resulted significant decrease values then corrected rate formula pure gas calculate size. showed gradually decreased filling organic molecule PEI. This provides new insights regulating polyethyleneimine modification, well structures organic-modified molecular sieves.