Synthesis and structure of ethylene bridged polysilsesquioxanes functionalized with different groups
Amino-, thiol-, urea-, and acethoxy- functionalized polysilsesquioxane xerogels have been obtained by co-condensation of 1,2-bis(triethoxysilyl)ethane with trifunctional silanes. The structural and chemical characterization of the xerogels was done by means of IR, 13C NMR, 29Si NMR spectroscopy, AFM, elemental analysis and nitrogen adsorption measurements. The resulting xerogels have a porous structure (SBET in the range 500-800 m2/g) and a high content of functional groups (2.3-2.7 mmol/g). Majority of these groups are accessible on the surface generating specific adsorption sites. The nature of the functional group introduced by co-condensation substantially influences the porous structure - the resulting samples can be microporous or mesoporous depending on the type of the group used.