The physics of Langmuir-Blodgett films

Abstract

Langmuir-Blodgett (LB) films are formed by the successive deposition of a series of monolayers of one or more types of amphiphilic molecules initially spread at the interface between water and air. They usually consist of a regular planar array of molecular layers having a well defined and predetermined thickness. Their properties have made them of interest to physicists, electronic engineers, chemists and biologists. This review is mainly addressed to physicists and device engineers but, since the topic is of an interdisciplinary nature, it is hoped that it may also be of use to research workers in other disciplines. The early development and essential technology of the subject are discussed and key papers are referred to. However, the review is mainly devoted to the large amount of recent work in the field. The application of LB films to the study of dye molecules and their interactions is not dealt with in any detail as this topic has been well reviewed elsewhere and leads, in any case, to the general study of dye molecules which is beyond the scope of this review. A wide variety of different types of amphiphilic molecule are discussed ranging from simple carboxylic acids via complex heterocyclic compounds to polymers. The various physical techniques used to determine the crystallographic structure of the films together with the influence of deposition methods on this structure are discussed. The study of the electric and optical properties of various LB films is described both in relation to the physical information which may be gained from these studies and also in respect of possible technical applications. The difficulties inherent in attempting to obtain good threedimensional crystallographic order in films are pointed out together with possible methods of overcoming these difficulties.

Self‐supporting Polymer from a POSS Derivative

“…13 C solid-state NMR spectra ( Figure S5 in the Supporting Information) suggest that the thermal annealing procedure does not change the chemical structure of the POSS-C11-Py because of its high decomposition temperature (T d , 5% ¼ 318 8C). Unlike films prepared as Langmuir-Blodgett films made from low molecular weight compounds, [25][26][27] this POSS-C11-Py film retained its shape without the need for any support, prompting us to further characterize the microstructure and hydrogen bonding interaction of the POSS-C11-Py through wideangle X-ray diffraction (WXRD) analysis. The WXRD patterns of both Py-C11ene and POSS-C11-Py (fresh) exhibit broad amorphous halos centered at 19.78 and 17.88, respectively (Figure 1(b)).…”

Langmuir monolayers of fractions of cork suberin extract

“…Such isotherms were obtained by spreading 80 l of a THF:chloroform solution (4:96) from each sample at the air-water interface. The subphase used in these studies contained CdCl 2 , whose ions allow the formation of cadmium salts leading to more stable monolayers [4,5]. The isotherms were recorded after waiting 5 min for solvent evaporation.…”

“…A variety of properties can be exploited in such materials, including biodegradability and biocompatibility, but an obvious difficulty, particularly for those having complex structures, lies in the need to establish structure-function relationships, particularly at the molecular level. In this context, the Langmuir monolayer technique, which is normally used to study monolayers at the air-water interface of synthetic amphiphilic polymers and fabricate Langmuir-Blodgett (LB) films for a variety of applications [4,5], has also been used to study complex natural polymers such as lignin and cellulose [6][7][8][9]. Langmuir films, however, have not been used in studies of suberin extracts -to the best of our knowledge.…”

Interfacially formed organized planar inorganic, polymeric and composite nanostructures

“…That technique was introduced by pioneering works of Langmuir and Blodgett [62,63] and since then was used in numerous works related to studies of fundamental phenomena at the gas-liquid interface and in researches directed to fabrication of new supramolecular functional assemblies and organized nanostructured films [64][65][66][67][68][69][70]. Monolayer and multilayer structures with controlled composition and architecture composed of various amphiphilic compounds and/or inorganic nanocomponents can be formed and then deposited on solid substrate surfaces by this method.…”