Silica hybrid preparation, methods

Methods of Rubber-Silica Hybrid Preparation through Sol-Gel Chemistry.61... 

METHODS OF RUBBER-SILICA HYBRID PREPARATION THROUGH SOL-GEL CHEMISTRY... 

By using a similar procedure for the preparation of hybrids of silica, hybrids materials consisting of other metal oxides were also prepared by the group of Wilkes [15]. For example, titania was incorporated into organic polymers by using the chemically controlled condensation (CCC) method for the preparation of poly(tetramethylene oxide)-silica or poly(dimethylsiloxane)-silica hybrids. Especially, in the case of the hybrid with poly (tetramethylene oxide), the modulus or ultimate strength of the hybrid increased in the presence of titania component, as shown in Table 3. This phenomenon was explained by the catalytic ability of... 

Preparation of a bioactive and degradable poly(epsilon-caprolactone) / silica hybrid through a sol-gel method. Biomaterials, 23, 4915-4921. 

Although the biocompatibility and biodegradability of these materials were rapidly determined, the bioactivity of Si02-PCL hybrid materials was not studied until recently [99]. In order to provide bioactivity to Si02-PCL hybrid materials, Rhee prepared triethoxysilane end-capped poly(s-caprolactone) which was then cocondensed with tetraethyl orthosilicate and calcium nitrate via the sol-gel method. The Ca-containing PCL/silica hybrid so obtained showed in vitro bioactivity and biodegradability. The hybridization procedure between the a,co-hydroxyl PCL and silica phases was proposed to be as follows ... 

The high-pressure polyimide synthesis from salt monomers was extended to the development of a new approach for hybrid materials composed of aliphatic polyimides and silica, wherein this method was combined with the sol-gel process [63,64]. The preparation process is outlined in Scheme 2, where aliphatic polyimide P-9PM was used as the polyimide component. 

In the present study, we describe the methods of preparing the silica hybrids of linear and branched fiinctional polysiloxanes which could be used as a support for metal complex catalysts. The way in which the catalyst operates when it is attached to the polysiloxane moiety of the hybrid suspended in a polysiloxane solvent should be similar to the way it operates when in solution. Thus, its high catalytic activity is expected. On the other hand, it is easily separated from the reaction products and may be recycled or used in the continuous process. A high catalytic activity and specificity may be achieved if a polymer with a highly branched structure is used for the immobilization of catalysts [1-3]. Considerable amounts of catalytic groups may be placed in the external part of the branched macromolecule. 

The novelty of this study was the preparation method of silica having a high number of surface silanol groups but very low number of adsorbed water molecules. The synthesis procedure consisted in obtaining a sol-gel silica cosynthesized or functionalized by covalent attachment of 3-aminopropyltriethoxysilane and 1,1,1,3,3,3-hexamethyldisilazane, respectively. These hybrid solids were tested in a sustainable method of transesterification of P- ketoesters. 

The acetone bath was used for the formation of pure polyaniline fibers by electrospinning method. " The fibres were collected in an acetone bath placed on the collector electrode. Because by placing the acetone bath make the excess of solvent to diffuse into the acetone allowing the pure polyaniline fiber formation. In another study, PANI/silica hybrid nanofiber webs were prepared by using... 

PANI/silica hybrid nanofiber webs were prepared by using two different methods. The first one was in situ polymerization of aniline-doped silica nanofibers in an ammonium persulfate solution and the second one was immersing the silica nanofibers into a PANl solution. Effects of different pol5mierization parameters on conductivity were investigated. The PANI/silica hybrid nanofiber web electric conductivity increased with increasing monomer concentration. The electrical conductivities of the hybrid web were 5 X 10-5,17 X 10-3, 4 5 X 10-3, 3 2 x 10 3, and 1.07 S/cm for 0.2, 0.5, 0.7, and 1.0 M aniline solutions and pure polyaniline, respectively. The electrical conductivity showed the maximum at 1.0 of the molar ratio of the oxidant and aniline and decreased with an increase of the oxidant concentration. This result was explained by the prevention of polymerization by excess oxidant. The molar ratio of oxidant and aniline is generally about 1.0 for s5mthesis of PANI. 

Mann and coworkers proposed a unique method to prepare nanohybrids of mesoporous silica and gold nanoparticles mediated by programmed DNA hybridization, as illustrated in Figure 4.21 [186], MCM-41 nanoparticles were first functionalized with a 3 -amino-terminated 12-base single strand oligonucleotide... 

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