Use for surface modification

Radiation-induced grafting and curing processes have been discussed in a number of reviews.203 28 291 The process is widely used for surface modification. Recent applications are the modification of fuel cell membranes and improving... 

Figure 2.2 A number of small thiol-containing molecules have proven useful for modification of gold or metallic surfaces. The dithiol derivatives provide better dative bond stability and can t be displaced easily by competing thiols or oxidation. Most thiol-containing compounds used for surface modification also contain terminal functional groups or reactive groups for coupling affinity ligands.

In the category of silicone coatings used for surface modification of the specific substrates, functional silicone fluids are often used, which can selectively interact with the chemical groups of the substrate, thus modifying its surface properties. The use of functional silicones in the textile industry has been discussed in a number of recent publications.5 421 422 The use of different types of high-performace silicone-coated textiles, which include elastomers and resins, has recently been reviewed.423 The use of functional silicones in personal-care products, for example, in shampoos and hair conditioners, mentioned before,381 provides another well-known example. 

Particle encapsulation is another technique that can be used for surface modification that involves the complete coating of a particle with polymer [104]. The net effective hardness in this case tends to be less than that of the core. Particle encapsulation in CMP, hence, could be used to reduce surface defects of the surface to be polished. It should be noted here that excessive coating of the particle could result in reduced abrasiveness and in problems with dispersion stability. 

Soon after the first reports on the layer-by-layer adsorption appeared, the method was also used for surface modification of polymers [60, 61], and for the preparation of composite membranes [62-65]. Composite membranes were obtained by alternate dipping of porous supports into solutions of cationic and anionic polyelectrolytes so that an ultrathin separation layer was... 

The same factors that determine the reactions in aqueous solutions self-evidently also occur at the particle surfaces in equilibrium with the solution. The benefit of recognizing this fact is that the same tabulations of critical properties may be used to predict the surface reactions. The sol particles may be considered to represent a rigidized macrocluster of ion species. It should, however, be kept in mind that corrections have to be made for the adsorption against an ion cloud and against a surface potential. Both the surface charge and the site distribution at the surface (the surface morphology) influence the gel formation and the surface precipitation as well. The specific adsorption may, of course, be used for surface modification of the particle surfaces. 

The attachment of trialkoxysilane functionality to polyolefins (HDPE, LDPE, PP) though grafting of vinylsilanes e.g. 40, 41) or silane functional acrylates e.g. 42) has been widely studied. The principal application of these materials is the preparation of moisture curable crosslinked polyolefins that arc widely used in the cable industry. Silane treatment has also been used for surface modification of polyolefins " and silane grafted polyolefins might also serve as precursors to graft copolymers. 

As a special source of particles, low-temperature plasmas are included in this section, which strictly speaking are sources of ionized atoms or molecules as well as photons and electrons that all may interact with the polymer. In addition to well-established low-pressure plasma sources, corona discharge or recently developed atmospheric pressure plasma sources may be used for surface modification. 

Figure 3.147 Typical strategies used for surface modification and hydrophilization of hydrophobic nanoc7stals. Reproduced with permission from Ref [150] 2007, American Chemicai Society.

Tab. 3 Several organic chemical treatments used for surface modifications...

The sulfonated PC has shown improvement in both surface wettability and electroosmotic mobility. As an alternative to coating the PC surface forming the wall, UV and excimer laser (at a wavelength of 248 nm) treatment of the PC surface has also been used for surface modification. PETG is another plastic material used for the preparation of microchips. Its surface can be modified easily by NaOH treatment, resulting in ester hydrolysis and the appearance of carboxylic groups on the surface. 

Chapter 5 by Ishihara and Fukazawa focuses on polymers obtained from 2-methacryloylo>yethyl phosphorylcholine (MPC) monomer. Indeed, the molecular design of MPC polymers with significant functions for biomedical and medical applications is summarized in detail. It is especially shown that some MPC polymers can provide artificial cell membrane-like structures at the surface as excellent interfaces between artificial systems and biological systems. In the clinical medicine field, MPC polymers have been used for surface modification of medical devices, including long-term implantable artificial organs to improve biocompatibilily. Thus some MPC polymers have been provided commercially for these applications. 

Various chlorosilanes may be used for surface modification. Data are shown in Table II.4 on the adhesion of spherical glass particles (diameter 70 /im) to a glass surface modified with different silanes. The degree of modification was monitored on the basis of the contact angle. 

One of the most important categories of products used for surface modification includes products like paints, inks, and polishes. Eventhough they form a small fraction of the composition of paints, inks, and polishes, surfactants are the most essential component of these products. 

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