Surface silica nanopartides

Plot (he number of molecules as a function of particle size for silica nanopartides dp < 50 nm). On the same (igure, plot the fraction of the molecules that appear in the surface of the particles. This will require certain assumptions that you should state. 

Table 2. Molecular weight of polySt grafted onto silica nanopartide surface.

Ding, X. Zhao, J. Liu, Y. Zhang, H. Wang, Z. (2004). Silica Nanopartides Encapsulated by Polystyrene via Surface Grafting and in situ Emulsion Polymerization. Material Letters, 58,3126-3130... 

Bagwe, R.P., Hilliard, LR. and Tan, W. (2006) Surface modification of silica nanopartides to reduce aggregation and nonspecific binding. Langmuir, 22, 4357-62. 

Effect of surface flmctionalization of M CM-41-type mesoporous silica nanopartides on the endocytosis by human cancer cells. Journal of the American Chemical Society, 128(46), 14792-3. 

Widely used methods in the synthesis of silica nanoparticles are the sol-gel process and flame synthesis [5]. The latter is an effective synthetic route to continuously produce extremely pure nanoparticles, but in many cases the final products are agglomerated or show low reactive surfaces that make them difficult to functionalize. Nevertheless, flame synthesis is a prominent method to commercially produce silica nanopartides in powder form [6]. It is being used since decades for the production of the so-called fumed siUca, which is a filler in many applications, for example, in the pharmaceutical or polymeric business [7]. The extension of this preparation route is the so-called flame spray pyrolysis that has expanded in the last two decades to many other material compositions and is a promising rapid technique for the production of nanopowders [8]. 

Conformal hydrophobic/hydrophilic and supethydrophobic/ hydrophilic thermal switchable surfaces were reported to be composed of LbL assemblies of PAH and silica nanopartides postfunctionalized by a thermosensitive polymer poly (N-isopropylacrylamide) and perfluorosilane for microfluidic valves. A tunable sigmoidal wetting transition from superfiy-drophobidty to superhydrophilidty via gradient UV ozone was demonstrated on a continuous nanostmctured hybrid film of silica nanopartides and PAH. ... 

Reaction of the sandwich-type POM [(Fc(0H2)2)j(A-a-PW9034)2 9 with a colloidal suspension of silica/alumina nanopartides ((Si/A102)Cl) resulted in the production of a novel supported POM catalyst [146-148]. In this case, about 58 POM molecules per cationic silica/alumina nanoparticle were electrostatically stabilized on the surface. The aerobic oxidation of 2-chloroethyl ethyl sulfide (mustard simulant) to the corresponding harmless sulfoxide proceeded efficiently in the presence of the heterogeneous catalyst and the catalytic activity of the heterogeneous catalyst was much higher than that of the parent POM. In addition, this catalytic activity was much enhanced when binary cupric triflate and nitrate [Cu(OTf)2/Cu(N03)2 = 1.5] were also present [148],... 

Metallic nanopartides were deposited on ceramic and polymeric partides using ultrasound radiation. A few papers report also on the deposition of nanomaterials produced sonochemically on flat surfaces. Our attention will be devoted to spheres. In a typical reaction, commerdally available spheres of ceramic materials or polymers were introduced into a sonication bath and sonicated with the precursor of the metallic nanopartides. In the first report Ramesh et al. [43] employed the Sto-ber method [44] for the preparation of 250 nm silica spheres. These spheres were introduced into a sonication bath containing a decalin solution of Ni(CO)4. The as-deposited amorphous clusters transform to polyciystalline, nanophasic, fee nickel on heating in an inert atmosphere of argon at a temperature of 400 °C. Nitrogen adsorption measurements showed that the amorphous nickel with a high surface area undergoes a loss in surface area on crystallization. 

Until the end of the last century, bulk chromatographic materials containing porous or nonporous particles were used. Monolithic materials made of synthetic or natural pol)7mers and silica-based monoliths with similar surface chemistry have also been used as additional chromatographic supports in the last 15—20 years. Due to the rapid interaction between the sample components and the surface, monolithic materials enable very fast chromatographic separation of large molecules such as proteins and nucleic adds and nanopartides such as viruses and protein aggregates [5,6]. 

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