Glycol-modified silanes

Brandhuber, D., Torma, V., Raab, C., Peterlik, H., Kulak, A. and Husing, N. (2005) Glycol-modified silanes in the synthesis of mesoscopically organized silica monoliths with hierarchical porosity. Chemistry of Materials, 17, 4262 1271. 

Keywords sol-gel chemistry, mesostructured monoliths, glycol-modified silanes... 

Modifications of alkoxysilanes with diols or polyols such as ethylene glycol, glycerol, etc. have been well known since the middle of the last century however, their application was hampered by their hydrolytic instability [7, 8]. Only in recent years is interest in this type of glycol-modified silanes increasing again because of some obvious advantages ... 

The extraordinarily good compatibility of ethylene glycol-modified silanes with lyotropic liquid-crystal phases of surfactant molecules was demonstrated by Hoffinann in 1998 [11,12]. 

The noncovalent adsorption of proteins by p.CP is experimentally simple, but suffers from the disadvantage that the attachment can be reversible by rinsing the pattern with certain buffers and detergents or replacement by other proteins in solution. Moreover, the orientation of the deposited protein is not controlled. Delamarche et al. proposed the use of stamps modified with poly(ethylene oxide) silanes.100 The modification was conducted by oxidation of the PDMS stamp and reaction with APTES to yield an amino-functionalized surface. The next step was the reaction with homobifunctional cross-linker BS3 to bind surface amino groups with poly(ethylene glycol) (PEG) chains (Fig. 14.10). 

If the electro-osmotic flow is not wanted, then either the surface of the side wall is coated or a modifier is added to the buffer. Trimethylchlorosilane is used commonly to neutralize the surface and eliminate the electro-osmotic flow. Other silanes are aminopropyl and octadecyl. One of the best methods to coat the surface is to use glycol-containing groups such as polyethylene glycol (>5000 m.w.)... 

Variation of the head group of the monolayer makes it possible to control wettability etc., and also allows the introduction of different chemical moieties with specific properties such as nonspecific binding of proteins to surfaces. For example the introduction of oligoethylene glycol functionality to the end of the alkyl chain results in protein-resistant properties (37). Thus instead of synthesizing different thiols/silanes with different head groups, it is more convenient to use a number of standard SAMs and subsequently perform reactions on SAMs to modify the surface chemistry. Performing reactions on... 

Surface graft polymerization of poly(ethylene glycol) acrylate was used to modify the surface of PDMS. Templates with channels were formed from this material and sol-gel chemistry was used to form amino-silane doped xerogel microarrays. These structures were then used to release nitric oxide at various rates, by control of micropattern dimensions, type and concentration of the amino-silane, and so on. This method parallels the use of polymers in controlled drug-delivery systems. ... 

Surface modifiers can be added to the talc by the talc supplier to improve or reduce various talc-polymer interactions. The choice and concentration of the modifier depends on the desired benefit in the talc composite. Silanes and titanates are used to improve the bond between the talc surface and the polymer. Other surface modifiers, such a glycols and sorbates, are used to improve dispersion of the talc in the polymer. Stearates, such as zinc or calcium stearate, are added to the talc or mixed into the compound to reduce die drool and lubricate die surfaces. Epoxies can be used to minimize interactions between talc and certain stabilizers or metal impurities. These surface-modified talc products are generally more expensive than untreated talc. The decision to use a surface-treated talc is based on cost-performance balance. Sometimes it is more cost-effective to add any additives during the compounding operation than have them added to the talc by the talc supplier. 

---