Multilayer film formation

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... 

Figure 5. Schematic representation of the pore structure of mesoporous silica, depicting the cylindrical pores in a regular hexagonal array. The sequential process of multilayer film formation and capillary condensation in this structure are illustrated.

The mechanism of multilayer film formation depends on the relation between adsorbate-adsorbate and adsorbate-solid interactions. The controlling parameter for the surface phase... 

Although a multilayer film formation is the mle at air-water interfaces [73-77], a monolayer film formation is the rule at sohd-water interfaces [68,78-86]. In fact, it is anticipated that study of monolayer adsorption of protein will shed light on understanding multilayer formation at air-water interfaees. 

The film quality can be characterized by the parameter 9(00), that depends on the film growth mechanism. Therefore, the further development of multilayer films formation theory must be connected with the study of the detailed kinetics of processes in adsorption layers. 

Fig. 10. Formation of noncentrosymmetric multilayer film by combining self-assembly and a surface S 2 reaction, where R = (CH2)30H procedure I = spin-coating followed by annealing at 110°C and procedure II = reaction of Cl2Si0SiCl20SiCl2, ie, a dilute solution of 4-[A/,A/,-bis-(3-hydroxyprop5l)-aminophenylazo]-4 -pyridine on a benzyl chloride SAM surface was used, resulting in facile formation of SAMs having high...

Negatively charged species such as carboxylic acid group in acid-treated CNTs can attract positively charged enzymes from solution as long as the pH value of the enzyme solution is controlled to be lower than the iso-electric point of the enzyme thus, multilayer films of the enzyme can be formed by the layer-by-layer technique. For example, five layers of GOx can be immobilized on the electrode surface by alternatively dipping a poly(diallyldimethylammonium chloride (PDDA))-functionalized GC into a CNT solution and a GOx solution (pH 3.8). Figure 15.15 illustrates the preparation process for the formation of a multilayer film of GOx on the electrode. 

M Remmers, D Neher, and G Wegner, Photo-cross-linkable poly(p-phenylcnc)s. Synthesis, Langmuir-Blodgett multilayer film properties and pattern formation, Macromol. Chem. Phys., 198 2551-2561, 1997. 

A standard procedure for manufacturing liposomes is the film-forming method where the phospholipids are dissolved in an organic solvent. By rotational evaporation of the solvent a thin, multilayered film of phospholipids arises at the inner wall of the vessel. Redispersion of this film in water or aqueous buffer results in the formation of vesieles. The size of these vesicles and the number of bilayers vary. Henee further manufaeturing steps have to follow to obtain defined vesieular dispersions with a suffieiently long shelf life. 

Hexacyanoferrates were immobilized on Au covered with SAM of 3,3 -thiodipropionic acid [86]. It has been found from voltammetric studies that the surface coverage of hexacyanoferrate is close to one monolayer and such an electrode exhibits very good surface redox behavior. Cheng et al. [87] have described the formation of an extremely thin multilayer film of polybasic lanthanide heteropolytungstate-molybdate complex and cationic polymer of quaternary poly(4-vinylpyridine), partially complexed with osmium bis(2,2 -bipyridine) on a gold electrode precoated with a cysteamine SAM. Consequently, adsorption of inorganic species might also be related to the properties of SAMs. This problem will be discussed in detail in a separate section later. 

Lu C, Mohwald H, Fery A (2008) Large-scale regioselective formation of well-defined wrinkles of multilayered films via embossing. Chem Mater 20 7052-7059... 

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