Organic film dissolved

The structure of the multilayered recording medium is shown in Figure 16.13 in Section 3.3. In general, it is difficult to pile up organic films alternately without influencing the other films. In the medium, PVA is selected as the nonphotosensitive transparent film because water and pyridine as solvents for PVA and urethane-urea do not dissolve the urethane-urea film and the PVA film, respectively. 

The substitution reaction of TC and dissolved SeK2 in the organic film with the third-order rate constant k. 

First A must diffuse through the organic film where no reaction is assumed to occur. Then it dissolves in the aqueous phase at the interface and diffuses through the aqueous film into the bulk, with or without reaction in the film. Then the rest of the reaction (or the entire reaction) is completed in the aqueous bulk. The concentration profiles of A, E, and R are shown in the figure. It is assumed that there is no depletion of E in the film, even if reaction should occur there. Mathematical analyses based on this representation (and its variants) have been attempted, for example, by Pereira et al. (1987), Woodley et al. (1991), Miyake et al. (1991), Kamat et al. (1992), Chae and Yoo (1997). The following treatment is based essentially on the rigorous analysis of Miyake et al. (1991). 

Biofilm [I, 5./.]. A biofilm is an organic film containing microorganisms embedded in polymeric substances. Biofilms typically consist of water, microorganisms, extracellular polymeric substances (EPS), embedded particles and debris, and dissolved substances. The unchecked development of biofilms on paper machines can result in sheet defects, breaks, malodours, and Microbiologically Influenced Corrosion (M.I.C.). 

As part of the manufacture of microelectronic circuits, silicon wafers are partially coated with a 5,400-A film of a polymerized organic film called a photoresist. The density of this polymer is 0.96 g/cm. After the wafers are etched, this photoresist must be removed. To do so, the wafers are placed in groups of twenty in an inert boat, which in turn is immersed in strong organic solvent. The solubility of the photoresist in the solvent is 2.23 10 g/cm. If the photoresist dissolves in 10 minutes, what is its mass transfer coefficient (S. Balloge) Answer 4 10 cm/sec. 

As with polyesters, the amidation reaction of acid chlorides may be carried out in solution because of the enhanced reactivity of acid chlorides compared with carboxylic acids. A technique known as interfacial polymerization has been employed for the formation of polyamides and other step-growth polymers, including polyesters, polyurethanes, and polycarbonates. In this method the polymerization is carried out at the interface between two immiscible solutions, one of which contains one of the dissolved reactants, while the second monomer is dissolved in the other. Figure 5.7 shows a polyamide film forming at the interface between an aqueous solution of a diamine layered on a solution of a diacid chloride in an organic solvent. In this form interfacial polymerization is part of the standard repertoire of chemical demonstrations. It is sometimes called the nylon rope trick because of the filament of nylon produced by withdrawing the collapsed film. 

Fig. 15. Schematic of the interfacial polymerization process. The microporous film is first impregnated with an aqueous amine solution. The film is then treated with a multivalent cross-linking agent dissolved in a water-immiscible organic fluid, such as hexane or Freon-113. An extremely thin polymer film...

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