Template-directed synthesis of dually porous periodic organosilicas with 1,5-bis-(2'-ethyl)-xylene bridging groups

Porous organosilicas with 1.5-100 mol.% of bridging 1,5-bis-(2'-ethyl)-xylene (BDEX) groups were synthesized by a template-directed procedure and characterized using FTIR spectroscopy, temperature programmed desorption mass-spectrometry, X-ray diffraction and methanol adsorption. The formation of dually porous structure, consisted in small low-ordered mesoporous (2-3 nm) MCM-41 type particles united in aggregates with wide interparticle pores (8-20 nm), was found. If the concentration of the BDEX groups is smaller than 10 mol.%, the BDEX groups can be thermally oxidized without dually porous structure damage. The aggregation of the primary particles by chemical cross-linking is an alternative way to form a network of large so-called 'transport' pores in the mesoporous material