Chemical surface functionalization

Photografting technologies, that is, the control of chemical surface functionalization by highly selective excitation with UV light, can be used for grafting to and grafting from and has been intensively explored for controlled functionalization of polymeric membranes [29]. 

Apart from wettability and the related spreading of hquids, chemically heterogeneous surface composition has a profound impact on adhesion and its respective failure mechanisms and defects [24]. Further relevant areas comprise release surfaces, corrosion, lubrication, as well as chemical surface functionalization in coatings, sensors and biomedical apphcations (stealth surfaces) [18]. These important phenomena together with related appUca-tions in miniaturized devices, where the tolerances for defects and lateral heterogeneities are rapidly decreasing, are in the focus of the microscopic techniques reviewed in this article. 

Yuan F-W, Yang H-J, Tuan H-Y (2012) Alkanethiol-passivated Ge nanowiies as high-performance anode materials for lithium-ion batteries the role of chemical surface functionalization. ACS Nano 6 9932-9942... 

Surface properties are generally considered to be controlled by the outermost 0.5—1.0 nm at a polymer film (344). A logical solution, therefore, is to use self-assembled monolayers (SAMs) as model polymer surfaces. To understand fully the breadth of surface interactions, a portfoHo of chemical functionahties is needed. SAMs are especially suited for the studies of interfacial phenomena owing to the fine control of surface functional group concentration. 

Adsorption and Surface Chemical Grafting. As with siHca and many other siHcate minerals, the surface of asbestos fibers exhibit a significant chemical reactivity. In particular, the highly polar surface of chrysotile fibers promotes adsorption (physi- or chemisorption) of various types of organic or inorganic substances (22). Moreover, specific chemical reactions can be performed with the surface functional groups (OH groups from bmcite or exposed siHca). 

Determination of surface functional groups, e.g., —OH, —C - C—, and >C = O, and identificadon of adsorbed molecules comes principally from comparison with vibrational spectra (infixed and Raman) of known molecules and compounds. Quick qualitative analysis is possible, e.g., stretching modes involving H appear for v(C—H) at 3000 cm and for v(0—H) at 3400 cm L In addition, the vibrational energy indicates the chemical state of the atoms involved, e.g., v(C=C) " 1500 cmT and v(C=0) " 1800 cm"L Further details concerning the structure of adsorbates... 

Broadening of the optimal pH range for reactive dye biosorption by chemical modification of surface functional groups of Corynebacterium glutamicum biomass... 

The ESTM experiment provides actually five measurable quantities tunnelling current, / at the applied voltage, U, and three dimensions, x, y, z. The standard STM can therefore easily be modified by recording the local l-Uy U-zy or /-z characteristics (z is vertical distance of the tip from the electrode surface). Plot of dl/dU or d//dz versus x and y brings additional information on the electronic and chemical surface properties (local work functions, density-of-states effects, etc.), since these manifest themselves primarily as l-U dependences. The mentioned plots are basis of the scanning tunnelling spectroscopy (STS). 

The overwhelming number of dendrimer-related reports flooding the chemical arena, particularly, in the last five years, has made it a difficult task to summarize all important developments in one treatise. The restricted scope of this chapter - supramolecular chemistry within dendritic materials - denotes the utilitarian character to the unique infrastructure of these materials. Surface coatings and attachments to molecular spheres should possess a common theme respective of their frameworks, and thus there should be less differentiation between the mode of construction but rather what is the surface functionality. 

The silica microspheres provide some diversity but not enough for many complex discrimination tasks. To introduce more sensor variety, hollow polymeric microspheres have been fabricated8. The preparation of these hollow microspheres involves coating silica microspheres by living radical polymerization, using the surface as the initiation site. Once the polymer layer forms on the silica microbead surface, the silica core is removed by chemical etching. These hollow spheres can be derivatized with the dye of interest. The main advantage of these polymer microspheres is the variety of monomers that can be employed in their fabrication to produce sensors with many different surface functionalities and polymer compositions. 

The elemental composition, oxidation state, and coordination environment of species on surfaces can be determined by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) techniques. Both techniques have a penetration depth of 5-20 atomic layers. Especially XPS is commonly used in characterization of electrocatalysts. One common example is the identification and quantification of surface functional groups such as nitrogen species found on carbon-based catalysts.26-29 Secondary Ion Mass spectrometry (SIMS) and Ion Scattering Spectroscopy are alternatives which are more surface sensitive. They can provide information about the surface composition as well as the chemical bonding information from molecular clusters and have been used in characterization of cathode electrodes.30,31 They can also be used for depth profiling purposes. The quantification of the information, however, is rather difficult.32... 

Pharmacological strategy of CNTs generally relies on four main critical issues (1) preparation of nanovectors, (2) uptake, (3) function, and (4) elimination (Fig. 12.4). The physicochemical characteristics of CNTs including size, shape, aggregation, chemical composition, surface functionalization, and solubility play an important role in the biodistribution and pharmacokinetics of nanomaterials (Champion et al., 2007 Kostarelos, 2003 Lacerda et al., 2006 Nishiyama, 2007 Oberdorster et al., 2005 Radomski et al., 2005)... 

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