Alkylsilane SAMs

Among the alkylsilane SAMs, octadecyltrichlorosilane (OTS) SAM has been the most widely studied and used in industry as an antistiction and friction-reducing organic modifier [28,40]. OTS SAM has shown higher hydrophobicity, lower coefficient of friction, and reasonable wear durability compared with the other SAMs with different terminal groups, such as azide (N3) and CF3 [15,41]. 

Pseudo atoms on different chains and those on the same chain interact with each other via a cut-and-shift Lennard-Jones potential. Lorenz et al. [82] modeled adhesion contact and friction for perfluorinated alkylsilane SAMs. The OPLS (optimized potential for liquid simulations) all-atom force-field parameters were used. The total potential energy for the system, is represented as a sum of nonbond interactions as well as energy contributions due to the distortion of bonds... 

A related technique was demonstrated by Shiku et al. (91), who formed alkylsilane monolayers at glass substrates and used electrochemical generation of OH radicals at the tip via the Fenton reaction to locally destroy the SAM. Diaphorase could then be patterned on the surface by physical adsorption to the undamaged hydrophobic areas or via covalent linkages to the radical-attacked areas. The former process was imaged in feedback mode with a ferrocenyl mediator and showed a decreased current over the disk of destroyed SAM and a constant background of enzyme activity over the rest... 

Self assembled monolayers (SAMs) have aroused wide spread interest as they provide an opportunity to define the chemical functionality of surfaces with molecular precision, thus creating potential applications related to the control of wettability, biocompatibility and the corrosion resistance of surfaces of a wide range of materials II), Two families of SAMs have received the most attention, SAMs of alkanethiols on gold and alkylsilanes on silicon. 

Alkanethiolate or alkylsilane self-assembled monolayers (SAMs) 108-115 110-116... 

However, the super-hydrophobic behavior of the TiO and SAM coated structures could not be reached. Nevertheless, such surfaces are valuable for appUca-tions where hydrophobic coatings, like alkylsilane, are unwanted and a biologically compatible surface like SU8 is needed, for example, in medical diagnostics and biochips. 

Surface modification can be achieved by binding of different substituted alkylsilanes at the surface. SAMs have been reported from alkyltrichlorosilanes with terminal groups of amine [552, 570], halogen [553-555, 572], alkyl (Ci 4,6-8,10,12,18) [556-558, 570-572],... 

Diaphorase patterns were also fabricated on the substrates immobiUzed with SAMs of different alkylsilane derivatives. A hydroxyl radical is generated at an SECM tip in a solution containing HjOj and Fe by Fenton s reaction ... 

Early work on the macroscopic friction of SAM films was carried out by DePahna and others using a pin-on-disk type friction tester, and they observed a low friction coefficient [1,13] however, their frictional property containing a wear resistance was demonstrated under a limited condition. For example, the self-assembled octadecyltrichlorosilane monolayer revealed a good wear resistance at low load [14], but failed to lubricate at a normal load of 1.0 N due to wear [15]. To overcome the poor wear resistance of thin films, a dual-layer film was prepared by a combination of aminoalkylsilane and stearic acid, which improved the wear resistance of the SAM film [16]. In this work, the authors also proposed a defect-free double layer on a flat substrate by chemical adsorption of alkylsilane compound. 

The growth of alkylsiloxane self-assembled multilayers (SAMs) has been performed by sequential growth under vacuum of C=C terminated alkylsilane and titanium hydroxide with ozone activation (see Fig. 4.27). The XPS investigation... 

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