Langmuir-Blodgett deposited monolayers

The Langmuir-Blodgett deposition is one of the best methods to prepare highly organized molecular systems, in which various molecular parameters such as distance, orientation, extent of chromophore interaction, or redox potential can be controlled in each monolayer. We have been studying... 

The focus in this chapter is on the scientific issues and challenges in the application of vapor deposited top metal contacts to devices fabricated from self-assembled monolayers (SAMs) and related films such as Langmuir Blodgett (LB) monolayers. Specifically the chapter will review the types of possible interactions... 

In the case of adsorption from solution, the surfactant layers are in equilibrium with the solution and will de-sorb on dilution. However, it would be very useful to produce adsorbed layers in both air and water, which will remain adsorbed. This can be achieved using the Langmuir-Blodgett deposition technique. The technique is based on the observation that if a surfactant, which is insoluble in water, is dissolved in a volatile, non-aqueous solvent and then spread on water, an insoluble monolayer of orientated surfactant molecules will remain at the air/solution interface. The effect of the spreading surfactant and its surface film pressure can be dramatically demonstrated by spreading hydrophobic talc powder on a clean water surface and then placing a... 

Vickery, S.A., and R.C. Dunn. 2001. Direct observation of stmctural evolution in palmitic acid monolayers following Langmuir-Blodgett deposition. Langmuir 17 8204-8209. 

Mono- and multilayer films of polyimides were successfully prepared using Langmuir-Blodgett technique. Monolayer films of polyamic acid long alkylamine salts were prepared at the air-water interface. The mono-layer films were deposited on appropriate plates to produce multilayer films of the precursor to polyimide films. Finaly, the polyimide multilayer films were obtained by treatment of the multilayer films of the polyamic acid amine salts with acetic anhydride and pyridine. The polyimide multilayer films had excellent coating ability giving a very smooth surface. They also exhibited insulating characteristics as reliable as polyimide thick films. 

Seki, T, and Ichimura, K. Formation and Langmuir-Blodgett Deposition of Monolayers of Poly(vinyI alcohol)s Bearing Azobenzene Side-Chains of Varied Spacer Length. Thin Solid Films 179, 365 (1989). 

The Langmuir-Blodgett deposition technique shows excellent promise for the assembly of films with noncentrosymmetric ordering and Coo symmetry. A system that was reported recently (3i) is shown in Figure 6.11. In this system, monolayers of the hemicyanine dye and the nitrostilbene... 

In Langmuir-Blodgett deposition (Fig. 10.24e), a film of molecules (with amphiphilic properties) is forced in a densely packed layer at a liquid-air interface or at a liquid-liquid (lipophilic/hydrophilic) interface. The substrate (submerged into the liquid beforehand) is pulled from the liquid to air to adsorb a monolayer. With this technique, the monolayer is forced into an organization by narrowing the organization area with movable sidewalls. The technique has been particular successful on molecules with liquid crystal properties [133, 87],... 

Development of a sensor for neurological ly active compounds using the vesicle system characterized here necessitates stabi i Ization of a functional receptor system onto a sol id substrate. Possible methods for this stabi I Ization are direct covalent attachment via the protein or the Iipid componentSt fusion of vesicular structures with the substrate(26), or incorporation of the protein Into a monolayer at an alr/water interface and transfer of the monolayer onto the substrate by Langmuir-Blodgett deposition techniques(27). 

This threshold speed 14i plays an important role in Langmuir-Blodgett deposits, in the study of molecular electronics or for the control of wettability. A monolayer of insoluble surface active agents floating on the surface of water is transferred to a plate drawn at speed V from the bath. We must have V [Pg.27]

Langmuir-Blodgett (LB) monolayer film deposition techniques have been employed for many years in the fabrication of multilayer thin film structures. The basic technique involves the preparation of various monolayer films at an air/liquid interface and the subsequent stepwise transfer of these monolayers to an appropriate substrate, thereby building up a supermolecular assembly. 

Films spread at liquid-liquid interfaces or on liquids other than water are discussed followed by the important effects of charged monolayers on water. Finally, the most technologically important application of Langmuir films, the Langmuir-Blodgett film deposited on a solid substrate, is reviewed. 

Deposited Langmuir-Blodgett films take on many of the same stmctures as the Langmuir monolayers discussed in Section IV-4C, and they are often compared to the self-assembling monolayers described in Section XI-IB. The area... 

From what you know about wetting, contact angles, and spread monolayers, explain why a Langmuir-Blodgett layer will deposit as a F type if there are nonpolar fatty acids, yet will switch to a Z-type deposition if bipolar alcohols or amines are added (see Refs. 175, 176). What defines the critical contact angle for the deposition change ... 

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