Langmuir-Blodgett films applications

Fluorinated Polymers with Functional Groups Synthesis and Applications. Langmuir-Blodgett Films from Functional Fluoropolymers... 

Transmission electron microscopy (TEM) can resolve features down to about 1 nm and allows the use of electron diffraction to characterize the structure. Since electrons must pass through the sample however, the technique is limited to thin films. One cryoelectron microscopic study of fatty-acid Langmuir films on vitrified water [13] showed faceted crystals. The application of TEM to Langmuir-Blodgett films is discussed in Chapter XV. 

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. 

Peterson I R 1987 Langmuir-Blodgett films structure and application J. Mol. Electron. 3 103-11... 

Application of vibrational spectroscopy to the study of structure-function relationship in Langmuir-Blodgett films... 

The application of Langmuir-Blodgett films as rectifiers and/or switches have been also proposed. Peterson [106] investigated two semiconductors polyparaphenylene 178 and polyphenylenevinylene 179 with these purposes in mind. These systems with the chain lengths of at least 20 units could also be used as photovoltaic devices since their electroluminescence should be readily detectable. The doping of such materials may be necessary but at present it is not clear whether they will form Langmuir-Blodgett films when doped. 

Chapter 7 now includes an introduction to structural transitions in Langmuir layers and examples of applications of Langmuir and Langmuir-Blodgett films. 

The results illustrated above show that the CFT method is suitable for making chemical-sensor measurements using both bulk polymers and, in particular, thin film materials that are intrinsically weak conductors. Therefore, the CFT looks premising for such materials as poly(phenylacetylene) derivatives 24., for which carefully shielded electrometer measurements have been required in the past because of current levels at the threshold of detectability. Furthermore, the fact that the CFT always makes AC measurements reduces the problem of DC polarization of electrodes. In addition, the CFT approach should be suitable for other "chemiresistor" applications, such as the metal-substituted phthalocyanines proposed by Jarvis et. al. 2 and for Langmuir—Blodgett films 26. which, because they are so thin, may prove impossible to use in parallel-plate form, but which can be routinely used with the high-sensitivity interdigi-tated-electrode approach provided by the CFT. 

Kusano, H. Kimura Shin, L Kitagawa, M. Kobayashi, H. Application of Cellulose Langmuir-Blodgett Films as Humidity Sensors, and Characteristics of the Sorption of Water Molecules into Polymer Monolayers. Thin Solid Films 1997, 295, 53-59. 

However, the successful use of processes dependent on Langmuir-Blodgett films for semiconductor applications is in doubt due to the presence of water and other detrimental contaminants in the films produced. The internal dislocations required for switching by the molecules may not be facile since the molecules are expected to be packed into semicrystalline phases in the Langmuir-Blodgett films. In addition, new developments in the field may obviate the need for such films as part of the device. 

The application of FT-IR to a wide variety of interfacial phenomena is possible using either attenuated total reflectance (ATR) or grazing angle reflection -absorption. The details of these optical techniques are discussed in a subsequent chapter, in the context of characterization of Langmuir - Blodgett films and self-assembled mono and multilayers. However, ATR has been applied in a number of other areas which will be mentioned here. 

Ashwell, G.J. (1999) Langmuir-blodgett films Molecular engineering of noncentrosymmetric structures for second order nonlinear optical applications. Journal of Materials Chemistry, 9, 1991-2003. 

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