Bridged Polysilsesquioxane Xerogels Functionalizated by Amine- and Thiol- Groups: Synthesis, Structure, Adsorption Properties

Abstract

Bridged polysilsesquioxane xerogels containing amine ( NH 2 ; NH(CH 2 ) 2 NH 2 ; NH) and thiol ( SH) groups were synthesized by hydrolytic polycondensation of 1,2-bis(triethoxysilyl)ethane, 1,4-bis(triethoxysilyl)benzene and appropriate trifunctionalized silanes in the presence of a fluoride-ion catalyst in an ethanol solution. 29 Si CP/MAS NMR give indication of the molecular framework of these materials formed by structural T 1 , T 2 and T 3 units. 3-aminopropyl or 3-mercaptopropyl groups accessible to proton or metal ions are fixed to the xerogel surface by the siloxane bonds. IR and 13 C CP/MAS NMR data clearly show that 3-aminopropyl groups form hydrogen bonds. The same data testify that all xerogels contain non-condensed silanol groups and some fraction of non-hydrolyzed ethoxygroups.Functionalized polysilsesquioxane xerogels obtained by means of organic spacers have a porous structure (500-1000 m 2 /g) and a high content of functional groups (1.0-2.7 mmol/g). AFM data indicate that xerogels are formed by aggregating primary particles-the size of such aggregates is in the range 30-65 nm. It was established that the main factors influencing the structure and adsorption properties considered hybrid materials are: the nature and geometrical size of the functional groups, spacer flexibility and, in some cases, the ratio of the reacting alkoxysilanes and the ageing time of the gel.

Amorphous and ordered organosilicas functionalized with amine groups as sorbents of platinum (II) ions

“…The molar ratios of TEOS/APTS and TEOS/TMPD in the reacting systems were 19:1 and 18:2. Such ratios were selected to achieve the high content of functional groups in the final materials and, in addition, to avoid fast gelation, which is often observed (even in the case of OMO samples) when the relative amount of amine-functionalized silane increases (Dąbrowski et al 2005). All synthesized samples (OMO and AFX) are non-swelling in common non-aqueous solvents.…”

An innovative series of layered nanostructured aminoalkylsilica hybrid material

“…According to the literature, T units are formed by silicon atoms bonded to carbon atoms of organic groups and Q units are silicon atoms of the siloxane and silanol groups. [37][38][39] The peak assignments are presented in Table 3, and the relative abundance values of the T and Q species in the hybrid samples are presented in Table 4. It is clearly observed that the peak areas of T total species decrease from sample S50 to S75, while an increase of the peak area of Q toral species is observed.…”

Ethylene and phenylene bridged polysilsesquioxanes functionalized by amine and thiol groups as adsorbents of volatile organic compounds

“…Cocondensation of bis(trialkoxysilane) with trifunctional alkoxysilane (in order to introduce on the surface amine-and thiol-groups) was performed successfully before and described in our previous works [21,22]. It was also determined by 13 C and 29 Si CP/MAS NMR and IR spectroscopy that xerogels contain 3-aminopropyl or 3-mercaptopropyl groups fixed to the surface by siloxane bonds.…”

“…All the synthesized xerogels were identified by IR, 13 C CP/MAS NMR and 29 Si CP/MAS NMR spectroscopy. The spectra of the samples 1, 2, 3 with detailed analysis were described by us elsewhere [22] so this would not be repeated here. Fig.…”