Surfactants in coatings

D Thetford - Applications of Oligomeric Surfactants in Coatings chapter in Surfactants in Polymer, Coatings, Inks and Adhesives - Sheffield Academic Press. To be published. 

S. Tolstaya, S. Shabanova, in Application of Surfactants in Coating Industry, Khimiya, Moscow, p. 141 (1976). 

Surfactants in paint function as an emulsifier for the binder, a dispersant for the pigment, and a wetting agent. However, in the dried paint film, a surfactant can soften the film and impair the durability of the paint [47]. The problems created by a residual surfactant in coatings can be avoided by using [1] a destructible or hydrolyzable surfactant [48] or [2] a polymerizable surfactant [47,49]. 

C Q—C g-ethoxylated quaternaries surfactants for coating polystyrene beads in the manufacture of lightweight concrete 17... 

Sucrose monoesters (SMEs) are used as nonionic surfactants, in detergents and as emulsifiers in foods. Some SMEs have bacteriostatic activity and are used to prevent spoilage in beverages. Semperfresh, an SME produced in the U.K., is used as a coating to extend the shelf life of fmits and vegetables (21,29). 

Self-assembled monolayers are formed spontaneously by the immersion of an appropriate substrate into a solution of active surfactant in an organic solvent. After the substrate is immersed for a time from minutes to hours, it is rinsed with ligroin, methanol, distilled water, and dried in a steam of nitrogen. An apparent effect of the monolayer coating is the drastic change in wettability of the surface so that the measurement of the contact angle can be considered as an effective way to detect the formation of the SAMs. 

Aid in the uniform dispersion of additives. Make powdered solids (e.g. particulate fillers with high energy and hydrophilic surface) more compatible with polymers by coating their surfaces with an adsorbed layer of surfactant in the form of a dispersant. Surface coating reduces the surface energy of fillers, reduces polymer/filler interaction and assists dispersion. Filler coatings increase compound cost. Fatty acids, metal soaps, waxes and fatty alcohols are used as dispersants commonly in concentrations from 2 to 5 wt %. 

Controlled/living radical polymerisation (CRP) is currently a fast developing area in polymer synthesis and it allows preparation of many advanced polymeric materials, including thermoplastic elastomers, surfactants, gels, coatings, biomaterials, materials for electronics and many others. 

The unique surface characteristics of polysiloxanes mean that they are extensively used as surfactants. Silicone surfactants have been thoroughly studied and described in numerous articles. For an extensive, in-depth discussion of this subject, a recent chapter by Hill,476 and his introductory chapter in the monograph he later edited,477 are excellent references. In the latter monograph, many aspects of silicone surfactants are described in 12 chapters. In the introduction, Hill discusses the chemistry of silicone surfactants, surface activity, aggregation behavior of silicone surfactants in various media, and their key applications in polyurethane foam manufacture, in textile and fiber industry, in personal care, and in paint and coating industries. All this information (with 200 cited references) provides a broad background for the discussion of more specific issues covered in other chapters. Thus, surfactants based on silicone polyether co-polymers are surveyed.478 Novel siloxane surfactant structures,479 surface activity and aggregation phenomena,480 silicone surfactants application in the formation of polyurethane foam,481 foam control and... 

An interesting sonochemical synthesis of elongated copper nanoparticles (approx. 50 X 500 nm) has been described [164]. The principle of the method is the use of an organised medium of aqueous cetyltrimethylammonium p-toluenesulphonate as the supporting fluid for sonication. The resulting nanoparticles are produced from the sonication of copper hydrazine carboxylate in the interconnected threadlike micelles which act as a template. The nanoparticles are coated with a layer of the surfactant. In the absence of the detergent the particles were spherical (ca. 50 nm). 

Component of liposomes Protective coating for liposomes Protein stabilizer DNA transfection agent Surfactant in intranasal or ocular delivery Increasing susceptibility of tumor cells to cytotoxic drugs Liver gene delivery... 

Asphalt emulsions are dispersions of asphalt in water that are stabilized into micelles with either an anionic or cationic surfactant. To manufacture an emulsion, hot asphalt is mixed with water and surfactant in a colloid mill that produces very small particles of asphalt on the order of 3 pm. These small particles of asphalt are prevented from agglomerating into larger particles by a coating of water that is held in place by the surfactant. If the asphalt particles agglomerate, they could setde out of the emulsion. The decision on whether a cationic or anionic surfactant is used depends on the application. Cationic stabilized emulsions are broken, ie, have the asphalt settle out, by contact with metal or silicate materials as well as by evaporation of the water. Since most rocks are silicate-based materials, cationic emulsions are commonly used for subbase stabilization and other similar applications. In contrast, anionic emulsions only set or break by water evaporation thus an anionic emulsion would be used to make a cold patch compound. 

Figure 26-24 Charge reversal created by a cationic surfactant bilayer coated on the capillary wall. The diffuse part of the double layer contains excess anions, and electroosmotic flow is in the direction opposite that shown in Figure 26-20. The surfactant is the didodecyldimethylammonium ion, (n-C,2H25)N(CH3)2, represented as in the illustration.

---