Structural analysis, water-soluble polymers

It has been found that the polymer surface having appropriately grafted nonionic, water-soluble polymer chains minimizes protein adsorption and cell adhesion. It should be noted that such minimum protein adsorption has been well known for a long time for hydrogels used for protein analysis such as polyacrylamine (PAAm) gel for electrophoresis, sephadex for protein gel filtration, and soft agar for cell culture. It is likely that the surface structure of these hydrogels resembles that of the grafted surface described above. 

Relatively purified proteins are easily crystallized at >1%, usually 5-10%, of the protein concentration in buffer. So, crystallization is the final stage of purification, and useful for storage of proteins and X-ray crystal structure analysis. In protein chemistry, crystallization does not mean the protein is 100% pure even though it is in crystalline form. As described for salting out, a crystallized protein is in a solid state together with precipitation aids such as salts, organic solvents, water-soluble polymers etc. 

This chapter covers the applications of Fourier transform infrared (FTIR) and Raman spectroscopy to the characterization of water-soluble polymers. The structural analysis of poly(oxyethylene), poly ethylene glycol), poly methacrylic acid), and poly acrylic acid), and the interactions of selected polymers with solvents and surfactants are presented. Structural features of these compounds in the crystalline and melt states are compared with their structural features upon dissolution in aqueous solvents. Special emphasis is given to the recent studies of the interactions between water-soluble polymers or copolymers and solvents or surfactants. New experimental approaches and the sensitivities of both FTIR and Raman spectroscopy to monitor such interactions are presented. 

Gel electrophoresis is widely used in the routine analysis and separation of many well-known biopolymers such as proteins or nucleic acids. Little has been reported concerning the use of this methodology for the analysis of synthetic polymers, undoubtedly since in many cases these polymers are not soluble in aqueous solution - a medium normally used for electrophoresis. Even for those water-soluble synthetic polymers, the broad molecular weight dispersities usually associated with traditional polymers generally preclude the use of electrophoretic methods. Dendrimers, however, especially those constructed using semi-controlled or controlled structure synthesis (Chapters 8 and 9), possess narrow molecular weight distribution and those that are sufficiently water solubile, usually are ideal analytes for electrophoretic methods. More specifically, poly(amidoamine) (PAMAM) and related dendrimers have been proven amendable to gel electrophoresis, as will be discussed in this chapter. 

Just about the same time Japanese workers (107) polymerized this dialdehyde with boron trifluoride etherate, p-toluene sulfonic acid, and titanium tetrachloride as well as with aluminum triethyl-water catalyst systems. Completely insoluble products were obtained with the cationic catalysts, whereas partially soluble materials were isolated with the latter initiator. On the basis of infrared evidence, the above structure was assigned to the soluble product. In spite of the fact that ether linkages were found by infrared analysis in the cationic product, the authors concluded that its structure was different from that of the soluble polymer obtained with organometallic catalyst. The structure of the soluble fraction was assumed to be ... 

M. C. Matulewicz and A. S. Cerezo, Water-soluble sulfated polysaccharides from the red seaweed Chaetangiumfastigiatum. Analysis of the system and the structures of the a-D-( 1 —>3)-linked mannans, Carbohydr. Polym., 7 (1987) 121-132. 

The mechanism of adhesion is also an important factor in failure analysis in composites [31]. Some adhesives work due to a physical entanglement of the resin into the wood structure whereas others require a free hydroxyl group on one of the cell wall polymers to participate in a chemical reaction with the resin. Substitution of hydroxyl groups was shown to decrease adhesion between chemically modified veneers due to the loss of hydroxyl functionality [32]. Resins that are water-soluble and depend on a hydrophilic substrate for penetration will be less efficient in chemically modified wood due to the decreased hydrophilic nature of the celt wall resulting from modification [33]. 

Oligomers also may adversely affect product propoties. Tauer and Bdinisdi [173] reported that the degree of dehydrochlorination of PVC increased with increasing amount of water-soluble oligomers in the sample. NMR analysis showed that the oligomers, which are formed during the emulsion polym -ization of vinyl chloride, have a structure similar to PVC,... 

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