Dialkylene Carbonate-Bridged Polysilsesquioxanes. Hybrid Organic−Inorganic Sol−Gels with a Thermally Labile Bridging Group

Abstract

In this paper, we introduce a new approach for altering the properties of bridged polysilsesquioxane xerogels using post-processing moaljzation of the polymeric network. The bridging organic group contains latent fbnctionalities that can be liberated thermally, photochemically, or by chemical means after the gel has been processed to a xerogel. These modifications can produce changes in density, volubility, porosity,' and or chemical properties of the material. Since every monomer possesses two latent functional groups, the technique allows for the introduction of high levels of functionality in hybrid organic-inorganic materials. Dialkylenecarbonate-bridged polysilsesquioxane gels were prepared by the sol-gel polymerization of bis(triethoxysilylpropyl)carbonate(1) and bis(triethoxysilylisobutyl)-carbonate (2). Thermal treatment of the resulting non-porous xerogels and aerogels at 300-350 'C resulted in quantitative decarboxylation of the dialkylenecarbonate bridging groups to give new hydroxyalkyl and olefinic substituted polysilsesquioxane monolithic xerogels and aerogels that can not be directly prepared through direct sol-gel polymerization of organotrialkoxysilanes.

Effective heavy metal removal from aqueous systems by thiol functionalized magnetic mesoporous silica

“…Modification with ligand, such as amines [10], carbonates and organosulfides [11][12][13], on the surface of mesoporous materials is necessary to obtain specific adsorption and larger capacity [14][15][16]. Thiol group is an excellent ligand because of the strong affinity to various heavy metal ions (Hg 2+ , Ag + and Pb 2+ , etc.)…”

Silica xerogels of tailored porosity as support matrix for optical chemical sensors. Simultaneous effect of pH, ethanol:TEOS and water:TEOS molar ratios, and synthesis temperature on gelation time, and textural and structural properties

“…The water:alkoxide and the solvent:alkoxide molar ratios [10,11], as well as temperature [4,12] have a significant influence on the sol-gel process and the microstructural properties of the final material [4,6,[13][14][15]. Drying of the gel is also a critical step.…”

“…When the pore liquid is removed as a gas phase from the interconnected solid gel network under supercritical conditions, the network does not collapse and a low density aerogel is produced. Although the effect of the synthesis conditions on the porous structure of silica gels have been extensively studied [4,6,[13][14][15], most of these works used the one variable at a time strategy that tacitly assumes that the variables are independent. Usually this is not true, and in these cases it is necessary to consider several factors simultaneously.…”

Synthesis of Inorganic and Organic–Inorganic Hybrid Hollow Particles Using a Cationic Surfactant with a Partially Fluorinated Tail

“…OIH materials are desirable for a variety of applications because the uniform distribution of the organic sites within the material imparts unique properties. [27][28][29][30][31] However, the number of reports of synthesis of hollow organic-inorganic particles has been limited. There have been several examples of polymerizing alkoxysilane-functionalized surfactants to form stable OIH vesicles.…”