Intermolecular bonding monolayers

Experimental data and calculations show that monolayers of compounds capable of formation of intermolecular H-bonds (such as amino- or hydroxy-terminated layers) have a network of such bonds on the surface of dry monolayers, but exposure to water vapours results in adsorption of water and disruption of the intermolecular bonds . ... 

This chapter presented the surface characterization of disulfide-linked Fc-peptide [Fc-Gl(OBz)CSA] 1, [Fc-Gl(OH)CSA] 2, [Fc-G20MeCSA]j 3, and [Fc-G2(OMe) CSA] 4. These systems have a disulfide group that was used for immobilization on An. On gold surfaces, the acids, unlike the corresponding esters, formed multilayers held together by intermolecular H-bonding. Monolayer coverages, however, are attainable by sonication in mixtures of solvents. CV measurements in the presence of [Fe(CN) ] " reveal that the Fc-peptide-modified electrodes exhibit excellent barrier properties. 

Fig. 6. Self-assembled monolayers are formed by immersing a substrate into a solution of the surface-active material. Necessary conditions for the spontaneous formation of the 2-D assembly include chemical bond formation of molecules with the surface, and intermolecular interactions.

FIGURE 3.1. (a) Schematics illustrating self-assembly. Self-assembled monolayers are formed by immersing a substrate (e.g.. a piece of metal) into a solution of the surface-active material. The functional end groups of molecules chemically react with the substrate material spontaneously, forming a two-dimensional assembly. Its driving force includes chemical bond formation of functional end groups of molecules with the substrate surface and intermolecular interactions between the backbones, (b) Cross-sectional schematic of self-assembled monolayers formed on a substrate. 

In a paper regarding phase transitions in monolayers,13 Cantor and Mcllroy incorporated the bond correlations and intermolecular interactions using an approach similar to that of Ref. 10. Finally, Cantor has incorporated the bond correlations in the generator-matrix formalism to calculate the elastic properties14 of films of athermal surfactant mixtures. 

In this paper, a physical picture equivalent to those of Leermakers and Scheutjens10,12 and Cantor13 is employed. However, a more simple generator-matrix methodology is used to examine the effects of the intramolecular interactions, the nearest-neighbor bond correlations, and the intermolecular interactions on the structural properties of end-attached chain monolayers. While equivalent to that developed in Refs. 10 and 12, the method is more simple and compact, and hence more convenient from a computational point of view. 

Culler et al. were able to distinguish between chemisorbed and physisorbed APS in DRIFT spectra of APS-coated silicon powder 22). Removal of physisorbed silane by exposure to warm water reveals a hydrolytically stable layer of APS with less than monolayer coverage, covalently bound to the surface. They concluded that intermolecular silane bonds are easily hydrolyzed and that the overall degree of condensation was unimportant to hydrothermal stability. Hydrothermal stability was only enhanced by increasing the number of direct surface bonds. The electro-osmosis study supports this view of APS surface chemistry. 

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