Langmuir-Blodgett trough

The diacetylene monomers can be spread as a monomolecular layer on the air-water interphase of a Langmuir-Blodgett trough. The molecules are well oriented because of the preferences of the hydrophilic head group of the monomer to be in coordination with the subphase. The monomers can be spread using a good solvent like chloroform. 

Much of the early work is reviewed by Brash and Lyman 1) and by Vroman 2). Protein adsorption is a very old field — the earliest studies probably being mono-molecular film observations using Langmuir-Blodgett troughs 3). A comprehensive monograph which reviews protein adsorption is now available 4). 

Figure 3.1. Constant perimeter Langmuir-Blodgett trough. The pulleys round which the PTFE coated tape passes are mounted on carriages which move so that the perimeter of the enclosed area remains constant but the area enclosed by the tape varies.

However, as pointed out earlier, the artificial bilayer membrane, the BLM, can be made to serve as a model for the reality of biomembranes. One forms the BLM itself (Section 14.2) and then introduces into it various entities in order to examine their chemical and electrochemical effects. The appropriate membrane can be assembled by the use of a Langmuir-Blodgett trough in which long lipid molecules (those that make up the bilayer) are floated on the surface of water and then gently pushed together by a plastic slider (Rejou-Michel and Habib, 1986). A sensitive mechanism measures the force of this pushing and then when the force necessary increases suddenly, one knows the molecules have all been pushed into contact and a monolayer formed. 

This is the pathway that leads to enzyme electrodes. Thus, Rejou-Michel et al. in 1986 used a Langmuir-Blodgett trough to assemble lipids by gently pushing them... 

The pendent drop technique has also been extended to studies of insoluble monolayers of phospholipids at the water/n-dodecane interface (Li et al. 1994b). In these experiments first a monolayer is produced on a water drop surface as described above. Then, the water drop is gently immersed into the second liquid, for example n-dodecane. Then the change of the drop size enables one to compress and expand the interfacial film. Again, the isotherm obtained with ADSA shows the same type of dynamic behaviour as measured with the classic Langmuir-Blodgett trough technique (Thoma Mohwald 1994). 

FIGURE 5.32 Schematic representation of the formation of mono-, hi-, and tri-layers of molecules from a Langmuir-Blodgett trough. (After Chemla, D. S. and Zyss, J. eds. 1987. Nonlinear Optical Properties of Organic Molecules and Crystals, Vol. 1, no. 4, Academic Press, San Dieo, CA.)... 

The surface pressure can be determined by direct measurement of the force acting on the barrier in the differential way. However, in the usual Langmuir-Blodgett trough systems, the surface pressure is mostly measured with the Wilhelmy plate by monitoring the change in the surface tension from that of pure water as mentioned above. 

Equipment for LB Deposition By now, many kinds of the LB deposition protocols have been achieved by developing a variety of Langmuir-Blodgett troughs. Many types of trough systems are produced by employing the basic design of the traditional film balance, as mentioned in the earlier section. 

Fig. 10 Cross-sectional view of a Langmuir-Blodgett trough.

Heath and coworkers [564] describe a rare example of one-dimensional organization in the absence of a template. They fabricated wires of Ag nanocrystals by compressing a dispersion of Ag nanocrystals (4.5 nm) in toluene at the air-water interface in a Langmuir-Blodgett trough. The wires were one... 

References 1 and 2 both discuss common equipment. Essentially, all LB film work begins with the Langmuir-Blodgett trough (alternatively called Langmuir trough... 

Martin P, SzablewsM M (2004) Langmuir-Blodgett troughs operating manual, 6th edn. http //www.nima.co.uk/manuals-2.aspx. Accessed 06 January 2010... 

BAM Experiments. For all experiments a Langmuir-Blodgett trough (NIMA-Technology, Coventry, England, Type 601 BAM) was filled with 200 mL of water (Elsa Purelab Ultra, 18.2 Mf2). Afterwards, stearic acid solution was spread at the water surface. After evaporation of the... 

FIGURE 3.20 Schematic diagram of a Langmuir-Blodgett trough. Surfactants on the water surface can be compressed by a moveable barrier while surface tension is measured. 

Grunfeld, R, A modular multifunctional Langmuir-Blodgett trough. Rev. Sci. Instrum., 64, 548, 1993. 

This is demonstrated in Fig. 8.14 for a monolayer of dimyristoylphos-phatidylethanolamine (DMPE). The DMPE layer is floating on a water surface in a Langmuir-Blodgett trough. As the layer is compressed by a floating teflon barrier, solid domains appear (bright areas). This phase transition continues until no dark areas are any longer visible. Since a helium-neon laser has been... 

Formation of the monolayer is usually done with a Langmuir-Blodgett trough. With the aid of a moveable barrier a dense monomolecular layer of the surfactant on the liquid phase is maintained and controlled with a thin WOhelmy plate, the force on which is proportional to the stuface tensions. A dipping device provides the application of the layer on the substrate. Depending on its quality (hydro- or lipophilic) the nature of the surface is reversed after sorption. Multiple immersions and emersions allow stacking of the layers. 

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