Layers multilayer films

Keywords Bioactive Layer-by-layer Multilayered films Polyelectrolyte self-assembly Remote release... 

Keywords Capsules Layer-by-layer Multilayer films Reaction vessels Self-assembly... 

The self-assembly process can be continued to form multilayer films of up to 25 layers [33,48,49]. The reliability of this process is illustrated in Fig. XI-3, where the thickness grows linearly with the number of reacted layers. These thick layers have many interesting applications. 

Clearly, it is more desirable somehow to obtain detailed structural information on multilayer films so as perhaps to settle the problem of how properly to construct the potential function. Some attempts have been made to develop statistical mechanical other theoretical treatments of condensed layers in a potential field success has been reasonable (see Refs. 142, 143). 

Ellipsometry measurements can provide infomiation about the thickness, microroughness and dielectric ftinction of thin films. It can also provide infomiation on the depth profile of multilayer stmctiires non-destmctively, including the thickness, the composition and the degree of crystallinity of each layer [39]. The measurement of the various components of a complex multilayered film is illustrated m figure Bl.26.17 [40]. 

Using this strategy, constmction of multilayer films of - O. fim thickness by self-assembly of methyl 23-ttichlorosilyltticosanoate (MTST) on siUcon substrates has been demonstrated (Fig. 9) (165). The linear relationship between the film thickness and the layer number showed a slope of 3.5 nm /layer. Filipsometry data, absorbance intensities, and dichroic ratios for the multilayers all suggest that the samples were composed of distinct monolayers. However, ir data indicated that there maybe more tilting or disordering of the alkyl chains in the seven-layer sample than for the monolayer samples. 

To begin with, let us eonsider an adsorption system, i.e., the film formed on the surfaee of the total area A and held at the temperature T. For the sake of simplieity, we also assume that the film is only one atomie layer thiek. The diseussion of multilayer films on heterogeneous surfaees is presented in the next seetion of this ehapter. 

It has been demonstrated in a very elegant way by Pandit et al. [168] that mechanism of multilayer film formation depends crucially on the ratio Vq/u. When this ratio is sufiiciently high, i.e., when the surface is highly attractive towards the adsorbate, the film grows in a layer-by-layer mode. At low temperatures this corresponds to the presence of a series of layering... 

In conclusion, one should choose an appropriate multilayer system for different application purposes. For the case of fatigue wear, multilayer films consisting of two hard materials with different shear modulus, such as DLCAVC multilayer film [115], would satisfy the requirement for wear resistance. While for abrasive wear, multilayer films consisting of hard ceramic layers and soft metal layers, such as TiN/Ti and CrN/Cr [116,117] multilayer films are more competent. 

The described procedure allows one to deposit protein, in particular, enzyme, LB films onto the surface of small spheres. Deposited multilayer film was washed in order to leave at the surface only a layer covalently attached to the activated surface. The enzyme... 

FIG. 2 -potential as a function of layer number for PDADMAC/PSS multilayers on sulfate-stabilized polystyrene (PS) latices. The multilayers were assembled onto the negatively charged PS latices ( -potential of ca. -65 mV, layer number = 0) by the consecutive deposition of PDADMAC (odd layers) and PSS (even layers). Positive values are observed for PDADMAC deposition, and negative values for PSS adsorption. The alternating values are characteristic of stepwise growth of multilayer films on colloids. 

What is the role of a tie layer in processes which create multilayer films ... 

Fluorescent nanotubes of polyethyleneimine (PEI) and 3,4,9,10-perylenetetra-carboxylicdianhydride (PTCDA) have been prepared through the alternating deposition of polymers and small functional molecules that form covalent bonds (Figure 7.10) [ 120]. The nanotube synthesis starts with the deposition of P EI in the pores of an AAO membrane as the first layer. The PTCDA solutionis then used to bind to the PEI via covalent bonding (Figure 7.10). The electro-optical properties of the small molecule (PTCDA) are retained in the multilayer films of PEI/PTCDA. The prepared nanotubes retain their fluorescent properties for up to 10 months without... 

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