Surface modification reactions

Surface Modification. Reaction or adsorption at the soHd surface can alter its properties and lead to a surface charge or steric stabilization... 

SAMs of OH-terrninated alkanethiols have been used in many surface modification reactions (Fig. 14). These reacted with OTS to yield a weU-ordered bdayer (322), with octadecyldimethylchlorosilane (323,324), with POCI3 (325—327), with trifluoroacetic anhydride (328), epichlorohydrin (329), with alkyhsothiocyanate (330), with glutaric anhydride (331), and with chlorosulfonic acid (327). 

Surface modification reactions OTC (GC) 139 etching HCl i O leaching HCl 140 particle depcaition 143 whisker formation 142 Surfactant mobile phases (LC) 408... 

Surface modification reactions are used to improve the wettability of glass surfaces by polar stationary phases and to Improve the extent of deactivation by sllylation" [138-146,166]. Miaaiuua procedures have been investigated but only a few are in use. Of these, the most important reactions are etching by hydrogen chloride, leaching with aqueous hydrochloric acid, formation of whiskers and solution deposition of a layer of solid particles. Because of the high purity and thinness of the... 

Other surface modification reactions that are relevant to biological studies include the binding of the blood anticoagulent, heparin,189 and of dopamine190 to polyphosp-hazene surfaces. The heparin immobilization brought about a five-fold increase in the coagulation time of blood, and the immobilized dopamine generated the same response in rat pituitary cells as did free dopamine. 

Results of the extent of surface modification reaction of the three silicas with the three organosilanes studied are shown in Table 1. 

For flat samples, the extent of surface modification reactions can be conveniently followed. For the iPP films analyzed in Sect. 3.5 in Chap. 3, the roughness variations due to surface modification were minimal. Thus, crosstalk in the force analysis shown in Fig. 4.8a (acquired using unmodified Si3N4 tips in ethanol) subsequent to oxyfluorination is minimized. 

Surface or bulk chemical reactions, including erosion and degradation are important aspects of polymeric systems. These processes can be desired, as is the case for surface modification reactions to increase, e.g., biocompatibility or drug delivery applications, while other processes are unwanted, such as ageing, degradation in harsh environments, or erosion. AFM approaches offer a unique possibility to study these processes in many cases under realistic conditions and thereby help identify the underlying mechanisms. 

Surface modification reactions used to improve the wettability of glasses by the stationary phase and to deionize some glasses, result in an increase in the activity of the glass surface. Without subsequent deactivation, colunms coated with nonpolar and moderately polar stationary phases exhibit undesirable chromatographic properties, such as tailing, incomplete elution of polar solutes and in extreme cases, sample... 

The surface-modification reaction between photo-Ti02 and H-siloxane is thought to be a dehydrogenation-condensation reaction, involving the Ti-OH group of the photo-Ti02 surface and the Si-H group of the H-siloxane [2], but confirmation has been slow because of the difficulty of... 

As has been discussed, a polymer exposed to a reactive plasma will be undergoing simultaneous surface modification reactions and surface removal reactions. If the removal rates dominate or if a non-reactive plasma is used, the polymer surface will contain a large number of free radicals when the plasma is turned off. These radicals may react with themselves to form cross-linking or unsaturation, they may react with the plasma gas as it decays after the power is turned off or, they will react with... 

Surface modification reactions are important not only for engineering of surface energy and interfacial properties such as wetting, adhesion, and friction, but also for providing active surfaces for the attachment of molecules with different properties such as polymers [552], ruthenium phthalocyanine (RuPc) [560], jr-electron moieties [561], and deoxyribonucleic acid (DNA) [566, 570]. Organosilanes with more than one reactive group have the potential of binding to more than one surface... 

Formation of PEG-DOPA-K multimers in solution was monitored by performing GPC of PEG-DOPA-K solutions incubated under conditions identical to the surface modification reactions (0.6M K2SO4, O.IM MOPS, pH 9.0 at 50°C). The presence of multimers at elution times about 60-62 min was clearly evident in the PEG-DOPA-K sample incubated at pH 9.0 (Pig. 6). Multimer formation was notably lower for PEG-DOPA and PEG-DOPA-K at pH 6.0, suggesting that both alkaline pH and the presence of lysine residues are important in forming multimers in solution under these conditions. 

Other inorganic nanodimension particles such as layered doubled hydroxides, multiwall carbon nanotubes, POSS, and nanographite can also be potential nanoclay-sized flame retardant additives. Chemical compatibility of these materials is possible with surface modification reactions. Char formation is also observed in some plastic matrices. To have commercial value, general cost and easy processing have to be achieved. 

The hydroxyl groups in the surface of cellulose fibrils offer rich possibilities for chemical modification. Fibrils are partially amorphous and MFC prepared from chemical pulps will be microporous due to the removal of lignin and hemicelluloses. To avoid unacceptably high consumption of reactants, surface modification reactions should therefore be designed so that penetration of chemicals into the fibrils is avoided. 

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