Silicon surface modification

A polymer should be readily wet with water for applications such as contact lenses and for the preparation of hydrogels for a variety of biomedical applications. Increased wettabilit) is reflected by reduced values of the contact angle of the polymer with water. Another application is silicone surface modification of wool for self-cleaning. ... 

Tung, W. S. Daoud, W. A., Effect of Wettability and Silicone Surface Modification on the Self-Cleaning Functionalization of Wool. J.Appl. Polym. Sci. 2009, 112, 235-243. 

Table 3 Different ways of porous silicon surface modifications before metal contact formation ...

Mizutani T, Dale C J, Chu W K and Mayer T M 1985 Surface modification in plasma-assisted etching of silicon Nucl. Instrum. Methods B 7 825-30... 

Rebenne, H. E., and Bhat, D. G., Effect of Diffusion Interface on Adhesion and Machining Performance of TiN-Coated Silicon-Nitride Cutting Tools, Proc. ThirdInt. Conf. on Surface Modification Technologies, Neuchatel, Switzerland (Aug., 1989)... 

Table 1 shows the kinetic data available for the (TMSjsSiH, which was chosen because the majority of radical reactions using silanes in organic synthesis deal with this particular silane (see Sections III and IV). Furthermore, the monohydride terminal surface of H-Si(lll) resembles (TMSjsSiH and shows similar reactivity for the organic modification of silicon surfaces (see Section V). Rate constants for the reaction of primary, secondary, and tertiary alkyl radicals with (TMSIsSiH are very similar in the range of temperatures that are useful for chemical transformations in the liquid phase. This is due to compensation of entropic and enthalpic effects through this series of alkyl radicals. Phenyl and fluorinated alkyl radicals show rate constants two to three orders of magnitude... 

The radical-based functionalization of silicon surfaces is a growing area because of the potential practical applications. Although further knowledge is needed, the scope, limitations, and mechanism of these reachons are sufficiently well understood that they can be used predictably and reliably in the modification of hydrogen-terminated silicon surfaces. The radical chemistry of (TMSlsSiH has frequently served as a model in reactions of both hydrogen-terminated porous and flat silicon surfaces. We trust that the survey presented here will serve as a platform to expand silicon radical chemistry with new and exciting discoveries. 

The resultant tailored interface is often vastly superior for biomedical applications over the native silicone interface. Furthermore, surface modification maintains the low materials cost and favorable bulk properties of the original silicone elastomer. The modification methods can be divided into physical and chemical techniques. 

Ikada Y. Surface modification of polymers for medical application. Biomaterials, 1994, 15, 725-736. James SJ, Pogribna M, Miller BJ, Bolon B, and Muskhelishvili L. Characterization of cellular response to silicone implants in rats Implications for foreign-body carcinogenesis. Biomaterials, 1997, 18, 667-675. 

Price C, Waters MGJ, Williams DW, Lewis MAO, and Stickler D. Surface modification of an experimental silicone rubber aimed at reducing initial candidal adhesion. J Biomed Met Res, 2002, 63, 122-128. 

Dominey RN, Lewis NS, Bruce JA, Bookbinder DC, Wrighton MS (1982) Improvement of photoelectrochemical hydrogen generation by surface modification of p-type silicon semiconductor photo-cathodes. J Am Chem Soc 104 467 82... 

Fig. 59. Molecular modification of semiconductor silicon surfaces. Removal of the oxide generates a hydrogen-terminated layer that reacts with a range of molecular functional groups including alkenes. 

Gao, T. Gao, J. Sailor, M. J., Tuning the response and stability of thin film mesoporous silicon vapor sensors by surface modification, Langmuir. 2002, 18, 9953 9957... 

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. 

In dentistry, silicones are primarily used as dental-impression materials where chemical- and bioinertness are critical, and, thus, thoroughly evaluated.546 The development of a method for the detection of antibodies to silicones has been reviewed,547 as the search for novel silicone biomaterials continues. Thus, aromatic polyamide-silicone resins have been reviewed as a new class of biomaterials.548 In a short review, the comparison of silicones with their major competitor in biomaterials, polyurethanes, has been conducted.549 But silicones are also used in the modification of polyurethanes and other polymers via co-polymerization, formation of IPNs, blending, or functionalization by grafting, affecting both bulk and surface characteristics of the materials, as discussed in the recent reviews.550-552 A number of papers deal specifically with surface modification of silicones for medical applications, as described in a recent reference.555 The role of silicones in biodegradable polyurethane co-polymers,554 and in other hydrolytically degradable co-polymers,555 was recently studied. 

Bioadhesion is an area of research important in the selection of biomaterials (e.g., for implants). It is also critical in the development of the new biofouling coatings. A system for bioadhesion studies was developed, in which silicones with chemically and topologically (microengineered) modified surfaces were evaluated in the studies of the response to such surfaces of a diverse set of organisms.559-561 A new study of micropatterning and surface modification of PDMS to control bioadhesion has been reported.562... 

The Stober method can be used to form core-shell silica nanoparticles when a presynthesized core is suspended in a water-alcohol mixture. The core can be a silica nanoparticle or other types of nanomaterials [46, 47]. If the core is a silica nanoparticle, before adding silicon alkoxide precursors, the hydroxysilicates hydrolyzed from precursors condense by the hydroxide groups on the surface of the silica cores to form additional layers. If the core is a colloid, surface modification of the core might be necessary. For example, a gold colloid core was modified by poly (vinylpyrrolidone) prior to a silica layer coating [46]. 

Zhao and Brittain [280-282] reported the LCSIP of styrene on planar silicon wafers using surface modifications of 2-(4-(ll-triethoxysilylundecyl)phenyl-2-methoxy-propane or 2-(4-trichlorosilylphenyl)-2-methoxy-d3-propane respectively. Growth of PS brushes from these SAMs has been successfully achieved factors that influence PS thickness included solvent polarity, additives and TiC concentration. Sequential polymerization by monomer addition to the same silicate substrate bearing the Hving polymer chains resulted in thicker PS films. FTIR-ATR studies using a deuterated initiator indicated that the initiator efficiency is low, and the... 

The hydrogen abstraction from the Si—H moiety of silanes is fundamentally important not only because it is the method of choice for studying spectroscopically the silyl radicals but also because it is associated with the reduction of organic molecules, process stabilizers and organic modification of silicon surfaces. 

Effect of surface modification on pull-out force of PPTA silicone rubber composite ... 

Inagaki, N., Tasaka, S. and Kawai, H. (1992). Surface modification of Kevlar 49 fiber by a combination of plasma treatment and coupling agent treatment for silicon rubber composite. J. Adhesion Sci. Technol. 6, 279-291. 

Therefore, surface modification strategies for the formation of direct silicon-carbon bonds require, first, a special pre-treatment of the silicon surface to prevent oxidation and, second, an activation of the silicon surface for subsequent reaction with organic moieties. This has been achieved by treatment of the silicon surface with hydrofluoric acid to generate a hydrogen-terminated Si(lll) surface, which can further react with unsaturated co-functionahzed alkenes in the presence of UV irradiation or by thermal activation [27,44,45]. Using this method, carboxylic acid modified silicon substrates have been successfully generated and coupled to thiol modified ONDs via a polylysine/sulfosuccinimidyl 4-(M-maleimidomethyl)-cyclohexane-l-carboxylate couphng (Fig. 12). 

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