Silanizing agents

Prepare a solution of the silanation agent. For trimethylchlorosilane, use toluene as the solvent. The minimum requirement of the silanation agent is calculated by assuming the surface density of silanol to be one functionality per 0.1 nm. ... 

Transfer the dried beads into a three-neck flask with a thermometer, a nitrogen inlet, and a ventilation stopcock. Add the solution of the silanation agent to the flask with nitrogen sparge. 

If a bulky silanation agent such as octyidimethylchlorosilane is used, there will be unreacted silanols left. These silanols can be end capped by reacting the silica beads with trimethylchlorosilane by repeating steps 4-7. 

T etrapropylammonium, phenylaminopro pyltrimethoxysilane (as silanization agent)/Si in framework (ZSM-5) 29Si 3H HETCOR [202]... 

Silica contains surface silanols, about 8pmol/m to be precise. They are derivatized with silanization agents in the presence of an appropriate scavenger of the side product(s). The most commonly used reagent is a monochloro silane ... 

Ismail, A.F., Kusworo, T.D., and Mustafa, A. (2008) Enhanced gas permeation performance of polye-thersulfone mixed matrix hollow fiber membranes using novel Dynasylan Ameo silane agent. /. Memhr. Sci.,... 

The subject of silane chemistry and its interaction with both glass surface and polymer resins have been studied extensively. Since the silane coupling agent for improving the bond quality has first appeared in the literature (Rochow, 1951), a wide variety of organofunctional silanes has been developed, prominently by Plueddemann and coworkers. An early compilation of this subject for epoxy and polyester matrix composites (Plueddemann et al., 1962, Clark and Plueddemann, 1963 Plueddemann, 1974), and more recent reviews on the use of silane agents and... 

Fig. 6 Common silanizing agents to promote covalent DNA immobilization a 3-amino-propyltrimethoxysilane (APS) b 3-mercaptopropyltrime1hoxysilane (MPS) c 3-glycidoxy-propyltrimethoxysilane (GPS)...

Tlie physical properties of the silica such as pore diameter play an important role in determining the amount of hydrocarbon which can be bound to the support. The latter is conveniently expressed by the carbon load Cs i.e., by the weight percent of caiton in the dry stationary phase as measured by elemental analysis. The carbon load of the product usually increases with the reaction time or temperature, as well as with the relative amount of the silanizing agent in the mixture, until a maximum value is reached. 

In the case of H-ZSM-S, as shown in Table 3, a nearly total inhibition is observed with a treated catalyst corresponding to a large amount of deposited silanating agent. 

Not only octadecyltrichlorosilane is unreactive towards dry silica at room temperature. This is also the case for the chlorosilanes and the methylchlorosilanes. It was stated earlier that the vapour phase reaction occurs at elevated temperatures (> 473 K). This high-temperature constraint limits potential gas phase silanizing agents to those which have a high thermal stability and sufficient vapour pressure. 

It is apparent that all glass and other apparatus used for the preparation of derivatives must be perfectly clean in order to prevent contamination. If septa are used to close reaction vessels, they should be used repeatedly only with caution in order that substances accidentally adsorbed on the septum do not cause the same difficulties. The surface of glass vessels is modified in special instances only when the reagents used for the derivatives are extremely sensitive to the activity of the glass. Silanization is a common modification of the surface of glass vessels. It is performed, e.g., by treatment with a 5% solution of dichlorodimethylsilane in toluene [22]. The silanized glass is then rinsed with methanol and dried. Other silanization agents can also be applied. 

To silanize a column, the silanizing agent (5-10%) is dissolved in a solvent such as methylene chloride, hexane, or toluene. It then is added to the inert phase or placed in the column if its walls are to be treated. The system is heated to about 50 "C for 10 minutes. The material then is rinsed 4-5 times with dry methanol and dried by passing air over or through it, as the case may be. 

Methylation artifacts have also been shown to occur during derivatization due to the presence of small impurities of methyl groups in derivatization reagents and during separation due to the silanizing agent (demethyldisilzane) used to prepare the GC column. ... 

Exfoliation of MMT in the polymer matrix has been shown to occur through a process called slurry compounding, in which the MMT swells in water and then is mixed with Nylon-6 under extrusion [86]. Other techniques include the addition of MMT to water and the subsequent replacement of water by alcohol or acetone with further addition of a silane agent to modify the clay and make it compatible with the polymer matrix [87-89]. Intercalated nanocomposites were also obtained by slurry compounding introducing an epoxy monomer in the hydrated MMT galleries [90]. 

Since silane agents are less effective with coupling lower-energy carbon black and CaCOs, other agents may be tried. For coupling these fillers, organometal-lic complexes based on "neoalkoxy" titanates and zirconates have been used as... 

Alternatively, as in Wacker Chemie s MONOSIL process, the extrusion steps can be combined into a one-step process for aeating a readily crosslinkable compound. Other suppliers such as Dow Coming have also tried to make one-step crosslinking easier for processors by offering preblended formulations that contain the aosslinking catalyst, peroxide and silane agent in one PE compoimd [15-3, 15-4). 

---