Charged polymer

We shall devote a considerable portion of this chapter to discussing the thermodynamics of mixing according to the Flory-Huggins theory. Other important concepts we discuss in less detail include the cohesive energy density, the Flory-Krigbaum theory, and a brief look at charged polymers. 

In this chapter, and throughout this entire book for that matter, we have been concerned with uncharged polymers. We shall conclude this chapter with a brief discussion of the osmostic pressure of charged polymer molecules. 

A correct value of the molecular weight is obtained for the charged polymer by the van t Hoff equation, provided that a large excess of indifferent electrolyte is present. These high concentrations are described as swamping electrolyte conditions. 

The detection of organic polymers in solution represents a more difficult problem, especially in industrial water and wastewater. In theory, charged polymers react with polymers of the opposite charge in solution and such reactions can be used to titrate the concentration of polymer present. There are a number of techniques using this method (65). 

Coa.cerva.tlon, A phenomenon associated with coUoids wherein dispersed particles separate from solution to form a second Hquid phase is termed coacervation. Gelatin solutions form coacervates with the addition of salt such as sodium sulfate [7757-82-6] especially at pH below the isoionic point. In addition, gelatin solutions coacervate with solutions of oppositely charged polymers or macromolecules such as acacia. This property is useful for microencapsulation and photographic apphcations (56—61). 

A number of cationic muds have been developed and used. These ate formulated around quaternary amines or positively charged polymers (108,109). The polymer in some iastances may be a cationic polyacrylamide. Poly(dimethylarnine-fi9-epichloiohydrin) is another material that has been used successfiiUy for drilling shale formations (110,111). Some of these additives may requite a salt such as sodium or potassium chloride for best results. 

To reduce or avoid agglomeration removal of certain impurities such as charged polymers could be effective - once identified, while to enhance agglomeration certain additives could be used as are commonly employed as flocculating agents to enhance solid-liquid separation in the water industry for example. These effects have to be determined empirically with care, however, since they can be pH and supersaturation dependent. 

As described earlier, Jordi Associates provides columns for both neutral and charged polymers. Table 13.1 lists the charge types of each phase. This will allow for planning a coherent strategy for method development. 

The suspension of influenza virus, strain A/X-53, was separated from the constituents of alantoic fluid by preparative size exclusion chromatography on a 10 x 120 cm column. The hemo-agglutination method revealed an elevated level (93%) of viral activity. The leakage of the bonded phases can be more efficiently minimized, however, with the use of positively charged polymers. 

Barendrecht et al. show that the charged polymer films are similar to porous metal... 

The process of adsorption of polyelectrolytes on solid surfaces has been intensively studied because of its importance in technology, including steric stabilization of colloid particles [3,4]. This process has attracted increasing attention because of the recently developed, sophisticated use of polyelectrolyte adsorption alternate layer-by-layer adsorption [7] and stabilization of surfactant monolayers at the air-water interface [26], Surface forces measurement has been performed to study the adsorption process of a negatively charged polymer, poly(styrene sulfonate) (PSS), on a cationic monolayer of fluorocarbon ammonium amphiphilic 1 (Fig. 7) [27],... 

Hoagland, DA Smisek, DL Chen, DY, Gel and Free Solution Electrophoresis of Variably Charged Polymers, Electrophoresis 17, 1151, 1996. 

Irish moss extract, or carrageenin, is a negatively charged polymer which reacts with positively charged protein molecules, imparting rapid increase in mix viscosity. There are many types used for ice cream, depending on the final use. It is generally used in conjunction with CMC or locust bean to prevent mix separation. Levels between 0.02 and 0.10% are recommended. 

Figure 20 Ion exchange of positively charged drug bound to negatively charged polymer network with hydronium ion generated by electrolysis of water by electric current.

Capillary gel electrophoresis is becoming very widely used in the biotechnology field for the high resolution separation of DNA and peptides according to molecular weight, but it has limited application for the analysis of surfactants (Wallingford, 1996). CGE does result in an increase in the resolution per unit time over SEC for charged polymers (Poli and Schure,1992). 

The encapsulation process used was the LbL method, employing alternately charged polymers, namely PDA [poly(diallyldimethylammonium chloride)] and PSS... 

A.P. Soldatkin, V. Volotovsky, A.V. Elskaya, N. Jaffrezic-Renault, and C. Martelet, Improvement of urease based biosensor characteristics using additional layers of charged polymers. Anal. Chim. Acta 403,... 

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