Langmuir-Schaefer films

FiG. 24 CVs of Langmuir-Schaefer films of cytochrome P450scc on indium-tin oxide glass plate (ITO) in 10 mM phosphate buffer containing 0.1 M KCl at a scan rate of 20 mV/s between 0.4 and -0.6 V vs. Ag/AgCl. 

FIG. 26 Cyclic voltammograms of 40 monolayers of Langmuir-Schaefer films of cytochrome P450SCC on indium-tin oxide glass plate (ITO) in 10 mM phosphate buffer at a scan rate of 20 mV/s between 0.4 and —0.4 V vs. Ag/AgCl. LS films on ITO worked as the working electrode, platinum as the counter, and Ag/AgCl as the reference electrode. Cholesterol dissolved in X-triton 100 was added 50 p.1 at a time (1) with cholesterol, (2) 50 p.1 of cholesterol, (3) 100 p.1 cholesterol, and (4) 150 p.1 of cholesterol. 

Guo CX, Boullanger P, Jiang L, Liu T. Colorimetric detection of WGA in carbohydrate-functionalized polydiacetylene Langmuir-Schaefer films. Colloids Surf Physicochem Eng Asp 2007 293 152-156. 

Wang, S.P. et al., Amphiphilic anthracyl crown ether. A Langmuir and Langmuir-Schaefer films study, Langmuir, 16, 4607, 2000. 

Paddeu S., Ram M. K., Carrara S., and Nicolini C., Langmuir-Schaefer films of poly (o-anisidine) conducting polymer for sensors and displays. Nanotechnology, 9, 228-236, 1998. 

Bavastrello V., Ram M. K., and Nicolini C. Synthesis of multiwalled carbon nanotubes and poly(o-anisidine) nanocomposite material Fabrication and characterization of its Langmuir-Schaefer films, Langmuir, 18, 1535-1541, 2002. 

Ram M. K., Manuela Adami A., Marco Sartore A., Marco Salerno, Sergio Paddeu, and Nicolini C., Comparative studies on Langmuir-Schaefer films of polyanilines, Synth. Met., 100, 249-259, 1999. 

V. BavastreUo, S. Carrara, M. K. Ram, and C. Nicolini, Optical and electrochemical properties of poly(o-toluidine) multiwaUed carbon nanotubes composite Langmuir-Schaefer films, Langmuir, 20, 969-973 (2004). 

P. Bertoncello, A. Natargiacomo, V. Erokhin, and C. Nicolini, Functionalization and photoelectrochemical characterization of poly[3-3 (vinylcarbazole)] multi-walled carbon nanotube (PVK-MWNT) Langmuir-Schaefer films. Nanotechnology, 17, 699-705 (2006). 

Figure 4 Schematic representation of the Langmuir-Schaefer method, (a) Langmuir film, (b) the sohd substrate is placed horizontally on the Langmuir film, and (c) the solid substrate is hfted with a Langmuir-Schaefer film.

BertonceUo, P., Ciani, I., Li, F, and Unwin, P.R. 2006. Measurement of apparent diffusion coefficients within lUtrathin Nafion Langmuir-Schaefer films comparison of a novel scanning electrochemical microscopy approach with cyclic voltammetry, i muir 22 10380-10388. 

The other method of monolayer transfer from the air/water interface onto solid substrates is illustrated in Figure 2. This method is called the Langmuir-Schaefer technique, or horizontal lift. It was developed in 1938 by I. Langmuir and V. Schaefer for deposition of protein layers. Prepared substrate horizontally touches the monolayer, and the layer transfers itself onto the substrate surface. The method is often used for the deposition of rigid monolayers and for protein monolayers, hi both cases the apphcation of the Lang-muir-Blodgett method produces defective films. 

Ou et al. [179] reported on the successful fabrication of X-deposited multilayer films using the Langmuir-Schaefer deposition technique [187]. They used a polysiloxane copolymer containing both a mesogenic and an NLO side chain (30). 

This chapter deals primarily with monolayers of surfactants at fluid interfaces, but some attention is also given to (nano) coatings such as Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) films, self-assembled monolayers (SAMs), and layers obtained by alternating polyelectrolyte deposition. Such coatings may be applied for the functionalization of surfaces, for instance, to achieve biocompatibility of biomaterials, improve specificity and selectivity of biosensors and membranes, and control immobilization of enzymes or cells in bioreactors. 

In the Langmuir-Schaefer method, a flat substrate is placed horizontally onto a compressed monolayer on the liquid-air interface. When the substrate is lifted horizontally and separated from the water subphase, the monolayer is transferred onto the substrate (Figure 4). The method is useful to transfer viscous films as well as monolayers of lipids and proteins. ... 

Langmuir-Schaefer transfer A Langmuir film transferred to a substrate by moving it parallel to the film. 

Pohjakallio et al. brought new insights for the preparation of bicomponent Langmuir-Schaefer (LS) films, espedaUy those containing blends of immiscible polymers such as PS and PMMA 10 1 and 5 1 (mass ratio) PMMA/PS blend films deposited on silica substrates have been investigated by AFM (topography and phase... 

The second way of preparing L-B monolayer structures, the horizontal lifting method, was introduced by Langmuir and Schaefer. In this method, a compressed monolayer first is formed at the water-air interface, and a flat substrate is then placed horizontally on the monolayer film. When the substrate is lifted and separated from the water surface, the monolayer is transferred onto the substrate, as depicted in Fig. 15(d). 

The Langmuir-Blodgett (LB) technique was successfully applied for the deposition of thin protein layers (Langmuir and Schaefer 1938, Tiede 1985, Lvov et al. 1991). LB organization of protein molecules in film not only preserved the structure and functionality of the molecules, but also resulted in the appearance of new, useful properties, such as enhanced thermal stability (Nicolini et al. 1993 Erokhin et al. 1995). 

Surface viscosity has an important influence on the deformation of films and can also provide information about structure. Gaines [14] describes various methods of measuring this quantity. The damped torsion pendulum as developed by Langmuir and Schaefer [65] is probably the best device for making such measurements. Recent measurements of this type have been made by Buhaenko et al. [66]. Malcolm [67, 68] and Daniel and Hart [69] have carried out experiments which illustrate the important influence which viscosity has on the study of isotherms. 

Figure 7.38. XPS spectrum of an ionic liquid, [EMIM][Tf2N], detailing the C(ls) and N(ls) regions. Since there are no peaks from the Au substrate, the film thickness is hkely >10nm. Also shown (right) is the comparison between XPS, ultraviolet photoelectron spectroscopy (UPS, Hel = 21.2eV, Hell = 40.8 eV radiation), and metastable impact electron spectroscopy (MIES). Whereas XPS and UPS provide information from the first few monolayers of a sample, MIES is used for zero-depth (surface only) analysis, since the probe atoms are excited He atoms that interact with only the topmost layer of sample. Full interpretations for these spectra may be found in the original work Hofft, O. Bahr, S. Himmer-lich, M. Krischok, S. Schaefer, J. A. Kempter, V. Langmuir 2006, 22, 7120. Copyright 2006 American Chemical Society.

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