Self-assembled monolayers solutions

A logical division is made for the adsorption of nonelectrolytes according to whether they are in dilute or concentrated solution. In dilute solutions, the treatment is very similar to that for gas adsorption, whereas in concentrated binary mixtures the role of the solvent becomes more explicit. An important class of adsorbed materials, self-assembling monolayers, are briefly reviewed along with an overview of the essential features of polymer adsorption. The adsorption of electrolytes is treated briefly, mainly in terms of the exchange of components in an electrical double layer. 

As discussed in Chapter III, the progression in adsoiptivities along a homologous series can be understood in terms of a constant increment of work of adsorption with each additional CH2 group. This is seen in self-assembling monolayers discussed in Section XI-IB. The film pressure r may be calculated from the adsorption isotherm by means of Eq. XI-7 as modified for adsorption from dilute solution ... 

Self-assembled monolayers (SAMs) are molecular layers tliat fonn spontaneously upon adsorjDtion by immersing a substrate into a dilute solution of tire surface-active material in an organic solvent [115]. This is probably tire most comprehensive definition and includes compounds tliat adsorb spontaneously but are neither specifically bonded to tire substrate nor have intennolecular interactions which force tire molecules to organize tliemselves in tire sense tliat a defined orientation is adopted. Some polymers, for example, belong to tliis class. They might be attached to tire substrate via weak van der Waals interactions only. 

Fig. 6. Self-assembled monolayers are formed by immersing a substrate into a solution of the surface-active material. Necessary conditions for the...

Surface properties are generally considered to be controlled by the outermost 0.5—1.0 nm at a polymer film (344). A logical solution, therefore, is to use self-assembled monolayers (SAMs) as model polymer surfaces. To understand fully the breadth of surface interactions, a portfoHo of chemical functionahties is needed. SAMs are especially suited for the studies of interfacial phenomena owing to the fine control of surface functional group concentration. 

Self-assembled monolayers are formed spontaneously by the immersion of an appropriate substrate into a solution of active surfactant in an organic solvent. After the substrate is immersed for a time from minutes to hours, it is rinsed with ligroin, methanol, distilled water, and dried in a steam of nitrogen. An apparent effect of the monolayer coating is the drastic change in wettability of the surface so that the measurement of the contact angle can be considered as an effective way to detect the formation of the SAMs. 

Most studies of ORR catalysis by metalloporphyrins have been carried out using water-insoluble catalysts absorbed on a graphite electrode in contact with aqueous solution. In a limited number of cases, four other approaches have been used catalysts imbedded in an inert film (i.e., Nafion or lipid) on the electrode surface self-assembled monolayers of catalysts catalysts in aqueous or mixed organic/aqueous solutions in contact with an electrode and catalysis in mixed aqueous/organic medium using... 

Self-assembled monolayers (SAMs) of alkanethiols, HS(CH2)nX, where X denotes various functional groups, are frequently used to prepare model surfaces [3-6]. Alkanethiols or alkanedisulfides chemisorb from a solution onto a surface coated... 

Y.S. Fung and Y.Y. Wong, Self-assembled monolayers as the coating in a quartz piezoelectric crystal immunosensor to detect salmonella in aqueous solution. Anal. Chem. 73, 5302-5309 (2001). 

A large number of examples of redox polyelectrolyte monolayers have been reported [42[. Anson described the adsorption of poly(acrylic acid) onto glassy carbon with electrostatic binding of Ru(NH3)6 and Co(NH3)6 ions from solution [43]. Finklea [44] adsorbed poly(4-vinyl-I-methyl-pyridinium methylsulfate) on self-assembled mercapto-undecanoic self-assembled monolayer (SAM) on gold electrodes to... 

These monolayers form themselves spontaneously by adsorption of suitable components from a diluted solution directly onto a surface. The formation of ordered and orientated monomolecular layers by spontaneous adsorption from a diluted solution is called self-assembling, the respective layers are called self-assembled monolayers (SAM) or self-organized monolayers. In the first part of this review, the coating of surfaces with functionalized SAMs will be examined. After that, some aspects of the attachment of the biomolecules onto these SAM-modified surfaces will be discussed. 

The Gibbs adsorption theory (Birdi, 1989,1999, 2002, 2008 Defay et al., 1966 Chattoraj and Birdi, 1984) considers the surface of liquids to be monolayer. The surface tension of water decreases appreciably on the addition of very small quantities of soaps and detergents. The Gibbs adsorption theory relates the change in surface tension to the change in soap concentration. The experiments that analyze the spread monolayers are also based on one molecular layer. The latter data indeed conclusively verifies the Gibbs assumption (as described later). Detergents (soaps, etc.) and other similar kind of molecules are found to exhibit self-assembly characteristics. The subject related to self-assembly monolayer (SAM) structures will be treated extensively (Birdi, 1999). However, no procedure exists that can provide information by direct measurement. The composition of the surface of a solution with two components or more would require additional comments. 

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