Biocidal materials

Zimmerli B, Zimmermann H, Marek B. 1979. [The transfer of biocidal materials from coatings to the gas phase Endosulfan.] Chemosphere 8 465-472. (German)... 

The oldest and still intensely used biocidal materials release silver ions. Variations in the design of such materials is still the subject of the majority of publications on antimicrobial coatings. The designs cover sparingly soluble silver salts [87], silver nanoparticles [88], silver nanocomposites [89], and elemental silver coatings [32], The release of the silver ions and of other biocides is controlled by the encapsulating matrix, the solubility of the compound, and the material/medium equilibrium constant. 

Amitai G, Andersen J, Wargo S et al. (2009) Polyurethane-based leukocyte-inspired biocidal materials. Biomaterials 30 6522-6529... 

Diallyldimethylammonium Chloride and Diallylguanidine Acetates on High Conversion for Creation of New Biocide Materials... 

This article devotes to investigation co-polymerization DADMAC and DAGA on high conversion for creation of new biocide materials. Kinetic studying is carried out on low conversion (less than 10%), that it doesn t allow using this method for producing of such... 

Szomolay et have developed a model to describe the interaction between biofilm thickness and biocides. They have postulated that in addition to the known mechanisms mentioned above (mechanisms 1, 2, and 3), some of the bacteria in a biofllm seem to be able to sense the biocidal material and actively respond to it. In this model, it is proposed that there is a relationship between the thickness of the biofilms and the activity of the biocide for the sessile bacteria. Put in simple words, the thicker the biofilm becomes, the more the bacteria learn to resist it. 

Ludensky, M. L., Himpler, F. J. and Sweeny, P. G., 1998, Control of biofihns with cooling water biocides. Materials Performance, 37(10), 50-55. 

This section cited some interesting polyviologens and reported a two-step synthesis by which two classes of polymers, polysiloxanes, and polyviologens are combined to produce a hybrid copolymer. The synthesis of an AB2-type monomer from TMDS and a vinyl monomer was achieved at room temperature. The first step of the reaction is quantitative and time dependent. The hybrid copolymer is characterized by FT-IR and H-NMR spectroscopy. The siloxane-based polymer without the Si-O-C bond is thermally stable. Applications of the hybrid copolymer are expected in the packaging and food industries and as a new biocidal material. 

Emulsion Adhesives. The most widely used emulsion-based adhesive is that based upon poly(vinyl acetate)—poly(vinyl alcohol) copolymers formed by free-radical polymerization in an emulsion system. Poly(vinyl alcohol) is typically formed by hydrolysis of the poly(vinyl acetate). The properties of the emulsion are derived from the polymer employed in the polymerization as weU as from the system used to emulsify the polymer in water. The emulsion is stabilized by a combination of a surfactant plus a coUoid protection system. The protective coUoids are similar to those used paint (qv) to stabilize latex. For poly(vinyl acetate), the protective coUoids are isolated from natural gums and ceUulosic resins (carboxymethylceUulose or hydroxyethjdceUulose). The hydroHzed polymer may also be used. The physical properties of the poly(vinyl acetate) polymer can be modified by changing the co-monomer used in the polymerization. Any material which is free-radically active and participates in an emulsion polymerization can be employed. Plasticizers (qv), tackifiers, viscosity modifiers, solvents (added to coalesce the emulsion particles), fillers, humectants, and other materials are often added to the adhesive to meet specifications for the intended appHcation. Because the presence of foam in the bond line could decrease performance of the adhesion joint, agents that control the amount of air entrapped in an adhesive bond must be added. Biocides are also necessary many of the materials that are used to stabilize poly(vinyl acetate) emulsions are natural products. Poly(vinyl acetate) adhesives known as "white glue" or "carpenter s glue" are available under a number of different trade names. AppHcations are found mosdy in the area of adhesion to paper and wood (see Vinyl polymers). 

Nitromethane. The nitroparaffins are used widely as raw materials for synthesis. Nitromethane is used to produce the nitro alcohol (qv) 2-(hydroxymethyl)-2-nitro-l,3-propanediol, which is a registered biocide useful for control of bacteria in a number of industrial processes. This nitro alcohol also serves as the raw material for the production of the alkanolamine (qv) 2-amino-2-(hydroxymethyl)-l,3-propanediol, which is an important buffering agent useful in a number of pharmaceutical appHcations. 

Papermaking additives can be categorized either as process additives or as functional additives. Process additives are materials that improve the operation of the paper machine, such as retention and drainage aids, biocides, dispersants, and defoamers they are primarily added at the wet end of the paper machine. Functional additives are materials that enhance or alter specific properties of the paper product, such as fillers (qv), sizing agents, dyes, optical brighteners, and wet- and dry-strength additives they may be added internally or to the surface of the sheet. 

Starch is subject to fermentation by many microorganisms and, unless the mud is saturated with salt or the pH is >11.5, a preservative or biocide must be added if the mud is to be used for an extended period of time. The most common biocide until the mid-1980s was paraformaldehyde [9002-81-7]. This material has been largely replaced by isothia2olones (at 5—10 ppm cone) (74), carbamates, and glutaraldehyde [111-30-8]. Alternatively, the biocide may be incorporated during the processing of the starch and is present in the commercial product. 

A classification by chemical type is given ia Table 1. It does not attempt to be either rigorous or complete. Clearly, some materials could appear ia more than one of these classifications, eg, polyethylene waxes [9002-88 ] can be classified ia both synthetic waxes and polyolefins, and fiuorosihcones ia sihcones and fiuoropolymers. The broad classes of release materials available are given ia the chemical class column, the principal types ia the chemical subdivision column, and one or two important selections ia the specific examples column. Many commercial products are difficult to place ia any classification scheme. Some are of proprietary composition and many are mixtures. For example, metallic soaps are often used ia combination with hydrocarbon waxes to produce finely dispersed suspensions. Many products also contain formulating aids such as solvents, emulsifiers, and biocides. 

A/-Chloroamidines are usehil for preparation of biocidal imidazoles (106) and thiadiazolines (107). Ai-Chloroguanidines, RNHC(=NC1)NHR, serve as starting materials for synthesis of imidazoles, oxadiazoles, and thiadiazoles (108,109). 

Other Uses. As a biocide, chlorine dioxide is more effective than chlorine over a wider pH range. Chlorine dioxide is also less corrosive and more compatible with some materials of constmction. Chlorine dioxide has a wide variety of small appHcations in drinking water, food processing (qv), cooling towers, and oil recovery. In these areas, chlorite is the preferred source of chlorine dioxide. 

A (316) stainless steel beaker that failed by waterline attack is shown in Fig. 2.7. The beaker contained water into which a chlorinated biocide tablet had been placed. The 0.020-in.-thick (0.051 cm) beaker material perforated near the waterline in less than 40 hours. This corresponds to a minimum localized attack rate of 4.4 in. (11 cm) per year. 

Record potential pollutant sources in the building. Note the locations of major sources. Major sources such as large items of equipment can be recorded on the floor plan. Record the names and locations of chemicals or hazardous substances used or stored within the building, such as those that may be contained in cleaning materials, biocides, paints, caulks, and adhesives. Ask your suppliers to provide you with Material Safety Data Sheets. You may be unaware of the potential hazards... 

It should be emphasized that ionic liquids are simply organic salts that happen to have the characteristic of a low melting point. Many ionic liquids have been widely investigated with regard to applications other than as liquid materials as electrolytes, phase-transfer reagents [12], surfactants [13], and fungicides and biocides [14, 15], for example. 

Water quality is important, not only from an environmental point of view but also in relation to the type of packing to be specified. Analysis of the circulating water is simple to obtain, but it is very seldom offered to the cooling tower designer. The quality, or lack of it, will determine the type of pack to be used, the selection of structural materials and whether the tower should be induced or forced draft, counterflow or crossflow. Water treatment, in the shape of chemicals to control pH and to act as counter-corrosion agents or as biocides, all has a bearing on tower selection. 

Recently, there has been much interest in developing water-soluble tributyltin biocides to lessen the costs of application, and to prevent fire hazards when treating material in confined spaces. Bis(tributyltin) oxide itself has a very low aqueous solubility ( 0.001%), but it may be made water-dispersible by the addition of certain (534, 535) quaternary ammonium salts. Formulations of this type, although currently under development as wood preservatives (534), have been used extensively in the United Kingdom for the treatment of stonework to eradicate fungal growths, algae, mosses, and lichens (535). 

Acquired resistance to biocides results fiem genetie ehanges in a cell and arises either by mutation or by the acquisition of genetic material (plasmids, transposons) from another cell (Table 13.5). 

METALWORKING FLUID Eluid applied to a tool and workpiece to cool, lubricate, carry away particles of waste and provide corrosion protection. Generally comprising neat mineral oils, or water-based materials, or a mixture of the two. Eluids may also contain emulsifiers, stabilizers, biocides, corrosion inhibitors, fragrances and extreme pressure additives. 

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