Sol−Gel Synthesis of Hybrid Organic−Inorganic Materials. Hexylene- and Phenylene-Bridged Polysiloxanes

Abstract

New highly cross-linked polysiloxanes were prepared by sol−gel polymerization of 1,6-bis(diethoxymethylsilyl)hexane (1) and 1,4-bis(diethoxymethylsilyl)benzene (2). Hydrolysis and condensation of 1 and 2 under acidic and basic conditions with 4 equiv of water led to the rapid formation of hexylene- and phenylene-bridged polysiloxane gels. The dry gels (xerogels) were intractable, insoluble materials that were noticeably hydrophobic, exhibiting no swelling in organic solvents or water. Most of the xerogels were high surface area, mesoporous materials. Hexylene-bridged polysiloxanes prepared under acidic conditions were always nonporous regardless of whether they were processed to afford xerogels or supercritically dried as aerogels. Hexylene-bridged polysiloxanes prepared under basic conditions and all of the phenylene-bridged polysiloxanes were mesoporous with surface areas as high as 1025 m2/g.

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

“…The sol-gel method provides here a possibility to design-on a molecular level-the considered materials keeping control over their chemical and physical properties, including structure-adsorption characteristics (Loy et al 1996;Dąbrowski et al 2007). Particularly, this method allows for obtaining micro-and mesoporous materials with high specific surface areas.…”

Olefin hydroformylation by sol-gel entrapped rhodium catalysts bearing hydrolysable ligands

“…Complexes [Rh(OMe)(cod)] 2 , 10 15 were prepared according to the literature. The co-condensation agent 1,2-bis(triethoxysilyl)ethane was prepared by metathesis of (triethoxysilyl)vinyl (Aldrich) followed by hydrogenation.…”

Synthesis and characterization of ladder-like phenylene-bridged polysiloxanes

“…Ladderlike Phenylene-bridged Polymethylsiloxane (L 1 ) [2,3,11]. The precoupling -synthesis of 1,4-bis(methyldiethoxysilyl)benzene (M 1 ) -was determined as follows.…”

“…From 1 H-NMR and 29 Si-NMR spectra it can be known that more than 85% of the Si-OEt had been hydrolyzed Generally there are three possible distinct peaks for silicon atoms with different degrees of condensation in the 29 Si-NMR spectrum [3,12]. Among them, the D 0 peak represents the Si atom with no siloxane linkages (HO-Si-OH, EtO-SiOEt).…”

“…But the publication about ladder-like arylene-or alkylene-bridged polysiloxane was very limited. Most work was about their gels [2][3][4][5]. Adrianov and coworkers and Oikawa and coworkers reported the 1,4-phenylene-bridged siloxane oligomer and polymethylsiloxanes [6][7][8], and proposed a ladder-like molecule structure.…”