Monolayers octadecylamine

FIG. 9 Silver nanoparticles capped by 4-carboxythiophenol electrostatically adsorbed to positively charged octadecylamine monolayers, (a) Mass uptake versus number of layers at subphase pH 12 and pH 9 the inset shows the contact angle of water versus the number of layers, (b) Absorbance spectra as a function of the number of layers transferred (left), with the inset showing the plasmon absorbance at 460 nm versus the number of layers. Thickness versus number of layers as determined by optical interferometry is shown on the right. (Reprinted with permission from Ref. 103. Copyright 1996 American Chemical Society.)... 

DNA solution (25 mg/mL) was used as a subphase. Octadecylamine monolayer was spread at the subphase surface and compressed to the surface-pressnre valne of 15 mN/m. The adsorption of DNA at the amine head groups was performed for 1 hour. Then the layer was compressed to 30 mN/m and the film was transferred onto solid snbstrates. 

In 1997, a Chinese research group [78] used the colloidal solution of 70-nm-sized carboxylated latex particles as a subphase and spread mixtures of cationic and other surfactants at the air-solution interface. If the pH was sufficiently low (1.5-3.0), the electrostatic interaction between the polar headgroups of the monolayer and the surface groups of the latex particles was strong enough to attract the latex to the surface. A fairly densely packed array of particles could be obtained if a 2 1 mixture of octadecylamine and stearic acid was spread at the interface. The particle films could be transferred onto solid substrates using the LB technique. The structure was studied using transmission electron microscopy. 

The use of ordered supramolecular assemblies, such as micelles, monolayers, vesicles, inverted micelles, and lyotropic liquid crystalline systems, allows for the controlled nucleation of inorganic materials on molecular templates with well-defined structure and surface chemistry. Poly(propyleneimine) dendrimers modified with long aliphatic chains are a new class of amphiphiles which display a variety of aggregation states due to their conformational flexibility [38]. In the presence of octadecylamine, poly(propyleneimine) dendrimers modified with long alkyl chains self-assemble to form remarkably rigid and well-defined aggregates. When the aggregate dispersion was injected into a supersaturated... 

As a cationic polymer and a cationic amphiphile, poly(allyl amine hydrochloride) (PAA) and octadecylamine (ODA) shown in Fig. 6 were used, respectively. The stability of the monolayers of the anionic amphiphiles was increased by polyion-complexation with PAA added in the aqueous subphase in comparison with Ca2+ salt formation. Ion complexation (1 1) of each anionic amphiphile with ODA was also performed at the air-water interface by spreading a chloroform solution of a 1 1 surfactant mixture. 

Transmission electron microscopy (TEM) has been an underutilized yet valuable too in particle size characterization of MC particles in LB films. Monolayer films of trioctylphosphine oxide-capped CdSe (18), spread as a monolayer on an aqueous subphase, were transferred to a TEM grid. A close-packed hexagonal arrangement of 5.3-nm (cr —4%) crystallites was found. TEM images were also obtained for HMP-stabilized CdS incorporated in BeH/octadecylamine films (79) and for CdS formed under an amine-based surfactant monolayer and transferred to a TEM grid (14). In one study, direct viewing of CdS and CdSe particles made from Cd2+-FA films on TEM grids was not possible due to poor phase contrast between the particles and the film (30). Diffraction patterns were observed, however, that were consistent with crystalline (3-CdS or CdSe. Approximately spherical particles of CdSe could... 

An outstanding example is the formation of PbS nanocrystals on monolayers of mixed arachidic acid and octadecylamine (39). By successive addition of octade-... 

Comyn [1] has pointed out that maximum bond strength and consequently greater adhesion between the substrate and polymer could be achieved with a monolayer of silane bound to both the adherend and adhesive. The current investigation was undertaken to evaluate the possibility of monolayer level depositions on silicon substrates by employing a few w -functionalized alkanoyl-substituted derivatives of APTES which will provide polar moieties as well. The interactions of these functionalized silanes covalently immobilized on silicon with octadecylamine and octadecanoic acid, used as models for basic and acidic polymeric adhesives, were also examined in this study. Characterization of the silanized surfaces as well as studies on their interactions with the above two chemical probes were carried out through ellipsometric and XPS measurements. 

A bare platinum electrode was coated with a close-packed monolayer of n-octadecylamine by retraction from the molten crystal compound (2). The contact angle of methylene iodide with the monolayer was 68° to 70°, which should be true if the film was close packed. This film-coated electrode was used with the FEP resin-covered gold electrode in the experimental sequence described... 

Figure 7. Effect of varying relative humidity on contact potential difference of platinum and platinum coated with monolayer of octadecylamine...

Hence a plot of cos B versus / /yi. should yield a straight line with an inclination given by the surface tension of the solid. Good and Girifalco used several liquids to verify this behavior. As an example they determined the surface tension of polytetrafluoroethylene and octadecylamine monolayers to be roughly 28 and 30 mN/m, respectively. 

Both Geddes and the Lakowicz group s have investigated the metal-enhanced fluorescence of fluorophores on silver island films (SIFs) [11,26,27] and variously aggregated silver nanoparticles in solution [28,29]. One example of enhancement on SIFs is discussed below [26]. In this work the distance-dependent MEF of a monolayer of sulforfiodamine B (SRB) on SIFs was studied. A SRB monolayer was electrostatically incorporated into the Langmuir-Blodgett (LB) layers of octadecylamine (ODA) deposited... 

Fig. 27. Optical micrographs of (A) oriented calcite nucleated under stearate mono-layers at [Ca] = 10 mM bar = 100 p,m. (B) Oriented vaterite crystals nucleated under octadecylamine monolayers. Arrows indicate crystals of different crystallographic orientation bar =100 /im.

Table I. Effect of Method of Film Preparation on Wettability of Octadecylamine Monolayers...

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