Films alternating layers

Barraud A, Leloup J, Gouzerh A and Palaoin S 1935 An automated trough to make alternate layers Thin Solid Films 133 117-23... 

Alternate-layer LB films (Y-type, ABAB) of long-chain amines and fatty acids maybe used for pyrroelectric appHcations (Fig. 5). Stearylamine, C gH2yNH2, and a series of straight-chain fatty acids, yield a thick film (several hundreds of monolayers) which gave a pyrroelectric coefficient of - 0.05 nC/(cm -K) (72). A coefficient of 0.3 nC/(cm -K) for an 11-monolayer sample of CO-tricosenoic acid and docosylamine C22H4 NH2 has been reported (73). 

Feitknecht has examined the corrosion products of zinc in sodium chloride solutions in detail. The compound on the inactive areas was found to be mainly zinc oxide. When the concentration of sodium chloride was greater than 0-1 M, basic zinc chlorides were found on the corroded parts. At lower concentrations a loose powdery form of a crystalline zinc hydroxide appeared. A close examination of the corroded areas revealed craters which appeared to contain alternate layers and concentric rings of basic chlorides and hydroxides. Two basic zinc chlorides were identified, namely 6Zn(OH)2 -ZnClj and 4Zn(OH)2 ZnCl. These basic salts, and the crystalline zinc hydroxides, were found to have layer structures similar in general to the layer structure attributed to the basic zinc carbonate which forms dense adherent films and appears to play such an important role in the corrosion resistance of zinc against the atmosphere. The presence of different reaction products in the actual corroded areas leads to the view that, in addition to action between the major anodic and cathodic areas as a whole, there is also a local interaction between smaller anodic and cathodic elements. 

Our results demonstrate well the complexities of polyelectrolyte adsorption and provide a basis for various surface treatments utilizing polyelectrolytes. They especially afford physical-chemical support for alternate layer-by-layer film formation of polyelectrolytes, which is becoming a standard tool for building composite polymer nano-films in advanced materials science. 

Y.D. Jin, Y. Shao, and S.J. Dong, Direct electrochemistry and surface plasmon resonance characterization of alternate layer-by-layer self-assembled DNA-myoglobin thin films on chemically modified gold surfaces. Langmuir 19, 4771—4777 (2003). 

Y. Lvov, B. Munge, O. Giraldo, I. Ichinose, S.L. Suib, and J.F. Rusling, Films of manganese oxide nanoparticles with polycations or myoglobin from alternate-layer adsorption. Langmuir 16, 8850-8857 (2000). 

The unique ability of these LbL redox multilayer systems with control of film thickness on the nanometer scale, the composition and thickness of each alternate layer separately as well as the surface charge by choice of the topmost layer brings about design and tailored properties of devices with important applications. 

LB films prepared from alternating layers of long-chain TCNQ and long-chain TTF and transferred to glass substrates Absorption spectra and conductivity measurements... 

Fig. 123a. Simplified structure of the polyion complex LB films showing ionically bound mono-layers of conjugated polymer sandwiched between stearylamine spacer groups with interdigitated hydrocarbon tails, b Simplified organization of the heterostructure LB films showing alternating layers of 1 1 PTAA-StNH2 and SPAn-StNH2 [767]...

The most important use of neutron diffraction in the general field encompassed by this book is in the study of alternating layers of deuterated and undeuterated films. At the time of writing, three papers have appeared on this topic. They are by Buhaenko et al. [56], Grundy et al. [57] and Stroeve et at. [58]. In the latter study, alternate layers of deuterated and undeuterated fatty acids were deposited and studied by neutron diffraction. Subsequently this ordered structure was destroyed by thermal diffusion and the gradual loss of order was monitored. The ordered structure is only destroyed at temperatures well above ambient. Applications of neutron diffraction to the study of lipid films at the air/water interface will be discussed in Chapter 8. 

In this chapter an attempt has been made to discuss ordered structures made using the LB technique and employing relatively simple molecules all of one kind. In the next chapter, films made from preformed polymers, from polymerisable small molecules and from alternating layers of two distinct kinds of molecule will be discussed. Once again the emphasis will be on structure and the characterisation of order. The discussion of lipids and lipid-like materials is deferred until Chapter 8 which will discuss biomembranes and bioactive molecules. At this stage the reader may well ask What of the vast number of other simple materials from which LB films have been made ... 

In this chapter we turn to the study of LB films formed from polymers and LB films consisting of alternate layers of two different amphiphiles. In principle, of course, it would be possible to superimpose successive layers of three or more distinct amphiphiles but little has been done in this direction. However, a few examples of more complex alternating structures will be considered. 

Other polymer films formed from alternate layers of two distinct materials will be discussed in Section 5.6... 

Recently Cresswell et al. [297] have produced alternating layer structures which they have characterised by SHG and X-ray diffraction and have obtained a partial degree of order. Era et al. [298] have produced thick alternating films which exhibit quadratic dependence of second harmonic intensity on film thickness and which show a reasonable degree of order when studied by X-ray diffraction. 

The obvious ways of producing non-centrosymmetic films are either to form Z layers or to form alternating layers of two distinct molecular species. In either case, the direction along which the phenomenon of... 

Figure 8. Schematic representation of a noncentrosymmetric Lang-muir-Blodgett film. The nonlinear chromophore is incorporated into alternate layers, those represented by the squares, for example.

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