Adsorption coating effects

DeFife K M, Hagen K M, Clapper D L, et al. (1999). Photochemically immobilized polymer coatings effects on protein adsorption, cell adhesion, and leukocyte activation. Journal of Biomaterials Science. Polymer Edition. 10(10) 1063-1074. 

Corrosion, determination of corrosion products on iron and steel surfaces, adsorption properties of ion exchangers, catalysis, surface reactions on catalysts, coatings, effect of the preparation parameters on the phase composition and the short-range order... 

As already mentioned, phenol derivatives are membrane-active microbicides. They adsorptively coat the surface of the microbe cell then, at a higher concentration, they are dissolved more or less rapidly and well by lipoids depending on their chemico-physical properties (see above). They attack the cell wall and penetrate into the cell. There are reactions with the protoplasm and the cellular protein enzymes are also inhibited as a result the oxidoreductases and the enzymes of carbohydrate and protein metabolism react particulary sensitively. Whether the phenol derivatives act microbistatically or microbicidally is purely a question of the application concentration. At low concentrations in ambient medium, there is only reversible adsorption of the phenolic active substance at the cytoplasmic membrane and the related inhibiting effect. As stated above the cell wall is only penetrated and destroyed and the microbe cell killed at higher concentrations. 

The efficacy of a preservative and the concentration level of a microbicide to be added are very much dependent on the germ content of the material to be protected. This is in particular valid for electrophilic active microbicides which in general react irreversibly with nucleophilic components of the microbial cell, that means that they are used up by being effective. But membrane active microbicides which adsorptively coat microbial cell walls are also withdrawn from action at least temporarily if large numbers of microbial cells are present. The exponential growth profile of microbes (p. 2) always has to be taken into consideration. 

Additives. Because of their versatility, imparted via chemical modification, the appHcations of ethyleneimine encompass the entire additive sector. The addition of PEI to PVC plastisols increases the adhesion of the coatings by selective adsorption at the substrate surface (410). PEI derivatives are also used as adhesion promoters in paper coating (411). The adducts formed from fatty alcohol epoxides and PEI are used as dispersants and emulsifiers (412). They are able to control the viscosity of dispersions, and thus faciHtate transport in pipe systems (413). Eatty acid derivatives of PEI are even able to control the viscosity of pigment dispersions (414). The high nitrogen content of PEIs has a flame-retardant effect. This property is used, in combination with phosphoms compounds, for providing wood panels (415), ceUulose (416), or polymer blends (417,418) with a flame-retardant finish. 

Among all the low energy interactions, London dispersion forces are considered as the main contributors to the physical adsorption mechanism. They are ubiquitous and their range of interaction is in the order 2 molecular diameters. For this reason, this mechanism is always operative and effective only in the topmost surface layers of a material. It is this low level of adhesion energy combined with the viscoelastic properties of the silicone matrix that has been exploited in silicone release coatings and in silicone molds used to release 3-dimensional objects. However, most adhesive applications require much higher energies of adhesion and other mechanisms need to be involved. 

We have developed a compact photocatalytic reactor [1], which enables efficient decomposition of organic carbons in a gas or a liquid phase, incorporating a flexible and light-dispersive wire-net coated with titanium dioxide. Ethylene was selected as a model compound which would rot plants in sealed space when emitted. Effects of the titanium dioxide loading, the ethylene concentration, and the humidity were examined in batches. Kinetic analysis elucidated that the surface reaction of adsorbed ethylene could be regarded as a controlling step under the experimental conditions studied, assuming the competitive adsorption of ethylene and water molecules on the same active site. 

Lakes are prepared by adsorption or precipitation of a soluble dye on an insoluble substrate (e.g., alumina). They are useful in fatty products that have insufficient moisture to dissolve dyes (coated tablets, cake mixes, hard candies, chewing gum). Lakes are insoluble in most solvents including water, have high opacity, are easily incorporated in dry media, and show higher stability to light and heat. They are effective colorants for candies, pills, fats, and oils. The main characteristics and differences between lakes and dyes are well documented. ... 

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