Surface Deposition Crosslinking

Researches have decorated CNT with CHT by surface deposition and crosslinking processes. In this method, the CHT macromolecules as polymer cationic surfactants were adsorbed onto the CNT surface. In this step, a stable dispersion of CNT was formed in an acidic aqueous solution of CHT. The pH value of the system was increased by ammonia solution, and so the CHT could no longer remain in solution. Consequently, the precipitated CHT was deposited on the surface of CNT to form a CHT coating. Finally, the surface-deposited CHT was crosslinked to CNT by glutaraldehyde, for potential applications of this composite in biosensing, gene and drug delivery. 

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The particles therefore lose their charge. Since the charge provides the colloidal stability, the colloidal paint destabilises and deposits on the nearest surface, the car body. Primer coatings 12-35 /im thick are applied according to primer type. Each particle also contains a crosslinker for the resin, usually a blocked isocyanate. After rinsing, the primed article is passed into a hot... 

Very thin films may be also obtained through adsorption of a thin layer from solution [11,71,74] or chemical grafting [98] which is achieved by a polymerization reaction at the surface. A polymer film may also be deposited on the surface by plasma polymerization [99]. It is then, however, usually crosslinked and chemically not well-defined. 

The grafting reaction seems to be more efficient on the PE surface than on the PP (Figure 4). This is consistent with observations made by Tazuke and coworkers (11). One explanation is that the primary formed radicals on PP are more likely to undergo rearrangement to chain end radicals than radicals on PE. For the same reason it is more difficult to crosslink PP than PE. The chain end radicals can easily diffuse into the polymer matrix and there be out of reach for deposited monomer. 

The structure of the so-called "composite" membranes used in reverse osmosis is also much more complex than the conventional, simplistic description of the ultrathin semipermeable film deposited on and supported by a porous substrate. Most of these membranes which exhibit high flux and separation are composed of an anisotropic, porous substrate topped by an anisotropic, ultrathin permselective dense layer which is either highly crosslinked, or exhibits a progressively decreased hydrophilicity toward the surface. The basic difference between the conventional anisotropic (asymmetric) membrane and the thin film composite is that the latter might be... 

In the process of plasma polymerization, a highly crosslinked polymer is deposited on the surface The deposited plasma polymer changes the surface properties of the substrate dramatically. It modifies the surface of powders in terms of surface energy, functional groups, wettability, interaction with polymers, and dispersion... 

The results presented here demonstrate that static SIMS has unique capabilities for the characterization of the surfaces of polymers that have been modified by metal deposition or by plasma or corona techniques. Especially, the introduction of unsaturation and crosslinking are aspects that in some polymers can be observed directly. The formation of low-molecular oxidized material that can be inferred from XPS studies, can also be observed directly. A limitation of the quadrupole-type instrument, which is still the most widely used, is its limited mass range and mass resolution. It can be expected that a considerably more detailed description of modified polymer surfaces can be obtained by application of the more powerful reflectron-type Time-of-Flight SIMS spectrometers, but such studies have, to date, not yet been published. 

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