Organic polymers, colloidal solutions

Several cleaning methods are used to remove the densified gel layer of retained material from the membrane surface. Alkaline solutions followed by hot detergent solutions are indicated for organic polymer colloids and gelatinous materials fouling. Ferrous deposits, t3 pical in water treatments, are usually removed with a citric or hydrochloric wash. [35]. 

Monodisperse spherical colloids and most of the applications derived from these materials are still in an early stage of technical development. Many issues still need to be addressed before these materials can reach their potential in industrial applications. For example, the diversity of materials must be greatly expanded to include every major class of functional materials. At the moment, only silica and a few organic polymers (e.g., polystyrene and polymethylmethacrylate) can be prepared as truly monodispersed spherical colloids. These materials, unfortunately, do not exhibit any particularly interesting optical, nonlinear optical or electro-optical functionality. In this regard, it is necessary to develop new methods to either dope currently existing spherical colloids with functional components or to directly deal with the synthesis of other functional materials. Second, formation of complex crystal structures other than closely packed lattices has been met with limited success. As a major limitation to the self-assembly procedures described in this chapter, all of them seem to lack the ability to form 3D lattices with arbitrary structures. Recent demonstrations based on optical trapping method may provide a potential solution to this problem, albeit this approach seems to be too slow to be useful in practice.181-184 Third, the density of defects in the crystalline lattices of spherical colloids must be well-characterized and kept below... 

The continuing developments in the preparation of dendrimers and hyper-branched polymers ° have moved this field into consideration by the polymer colloids community. As dendrimers and hyperbranched polymers get ever larger, their dimensions become sufficient to consider their solutions as molecular polymer colloids. Inevitably, therefore, research into such polymers will feature in new directions for polymer colloids research, both as polymer colloids in their own right and as additives for modification of the properties of existing polymer colloids. Such research will be most effective if carried out through collaborations of organic and polymer chemists with colloid scientists. 

Organic polymers are comparable to the above catalysts, having microenvironments different from those of the surrounding media and being swellable (see 14.2.4.1). Micelles, which are colloidal species produced by aggregation of ca. 20 to thousands of surfactant molecules or ions with both polar and nonpolar portions, also have these characteristics. In a typical aggregate, the hydrophobic ends of the molecules are clustered in the core of the micelle, and the polar ends are located at the interface to the aqueous phase. Micelles may be spherical or (in highly concentrated solutions) cylindrical or lamellar. Inverted micelles may form in a hydrocarbon solvent. 

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