Structure-adsorption properties of ethylene-bridged polysilsesquioxanes and polysiloxanes functionalized with different groups

Amino-, thiol-, urea-, acethoxy-, cyano-, isocyanato-, chloro-, vinyl-, and phenyl-functionalized polysilsesquioxane and polysiloxane xerogels have been obtained by co-condensation of 1,2-bis(triethoxysilyl)ethane (BTSE) or tetraethoxysilane (TEOS) with appropriate trifunctional silanes (FOSs). The structural and chemical information were derived from the data of FT-IR, AFM, elemental analysis and adsorption measurements. The resulting xerogels have a porous structure (SBET in the range 500-1200 m2/g) and a high content of functional groups (2.3-4.0 mmol/g). Properties of the resulting samples depend on two factors: structure building agent used in the synthesis (BTSE vs. TEOS) and the nature of the organic pendant group introduced by co-condensation. The presence of the ethane bridges in the silsesquioxane network makes the resulting materials more robust. The aging time was found to have a drastic effect on the structure-adsorption characteristics of the polysiloxanes.