Langmuir—Blodgett deposition

The transfer of Langmuir films from the air-liquid surface to a solid substrate has come to be known as Langmuir-Blodgett deposition, after its developers [130, 131]. The solid substrates are usually hydrophilic surfaces such as... 

Peterson I R, Veale G and Montgomery C M 1986 The preparation of oleophilio surfaoes for Langmuir-Blodgett deposition J. Colloid Interface Sc/. 109 527-30... 

Rees and co-workers23 first studied the effect of the deposition of thin HRI overlays onto LPGs by analyzing the wavelength shift of the attenuation bands. The Langmuir-Blodgett deposition technique was exploited to deposit an incrementally thicker overlay (up to few hundreds of nanometers) of an organic material whose refractive index was 1.58. 

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... 

P. A. Suci and W. M. Reichert, Determination of fluorescence density profiles of Langmuir-Blodgett deposited films using standing light waves, Langmuir 4, 1131-1141 (1988). 

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... 

We report here on the structure and gas transport properties of asymmetric membranes created by the Langmuir-Blodgett deposition of ultra-thin polymeric lipid films on porous supports. Transmission and grazing angle FTIR spectroscopy provide a measure of the level of molecular order in the n-alkyl side-chains of the polymeric lipid. The level of orientational order was monitored as a function of the temperature. Gas permeation studies as a function of membrane temperature are correlated to the FTIR results. 

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. 

Detailed information about the components of the second-order susceptibility y2)(-2w to, w) can be obtained from second harmonic measurements on well-defined samples such as single crystals or oriented thin films, the latter obtained by procedures such as the asymmetric Langmuir-Blodgett deposition technique or electric-field poling of NLO chromophore-doped polymers.31 In the case of single-crystal samples, the second harmonic is... 

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],... 

The most commonly used template particles are either polystyrene or silica spheres. These can be synthesized or obtained commercially and are available in a range of sizes (from about 100 nm upwards) with a narrow coefficient of variation (<2%) in diameter. The size variation is important because the more uniform the size of the particles the more regular the packing. The particles can be assembled into templates in a variety of ways, including evaporation of the solvent [138], convective self-assembly [139-141], Langmuir-Blodgett deposition [142, 143], or by withdrawing the substrate slowly from a suspension of the colloidal particles [144]. The optimum methods for the assembly of the silica and polystyrene particles differ because of the differences in their densities and hence sedimentation rates. Once assembled on the surface the particles act as a template to define the deposition. 

An extension of artificial membranes for ion selective electrochemical work was the construction of biomimetic ion channel sensors [65]. These devices were based on Langmuir-Blodgett deposition of charged lipid membranes onto a glassy carbon electrode. This work indicated that a conductive zone can be opened reversibly by a stimulant-membrane interaction by surface charge alterations. This work has demonstrated how the concept of the conductivity measurement could be extended to the more common and useful technique of cyclic voltammetry. 

Finally, Berger et al [192] have developed a teehnique whereby an array of force curves is obtained over the sample surfaee ( force-curve mapping ), enabling a map of the tip-sample adhesion to be obtained. The authors have used this approaeh to image differently oriented phase domains of Langmuir-Blodgett-deposited lipid films. 

Aveyard R., Sinks B.P., Fletcher P.D.I. and Ye X. 1995. Contact angles and transfer ratios measured during the Langmuir-Blodgett deposition of docosanoic acid onto mica from CdClj subphases, Colloid Surf., A Physicochem. Eng. Aspects, 94, 279-289. 

Honig E.P. 1973. Langmuir-Blodgett deposition ratios, J. CoUoid Interface Sci., 45, 92-102. 

Petrov J.G. and Petrov P.G. 1998. Molecular hydrodynamic description of Langmuir-Blodgett deposition, Langmuir, 14, 2490-2496. 

Zhang L.Y. and Srinivasan M.P. 2001. Hydrodynamics of snbphase entrainment during Langmuir-Blodgett deposition, Colloids Surf., 193, 15-33. 

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). 

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