Alginate monomers

Figure 5 Mannuronic (A) and gluronic acid (B) components of alginate monomers...

T. Salomonsen, H.M. Jensen, D. Stenbaek and S.B. Engelsen, Chemometric prediction of alginate monomer compositions A comparative spectroscopic study using IR, Raman, NIR, and NMR, Carbohydr. Polym., 72, 730-739 (2008). 

Figure 17.2 Structural characteristics of alginates (a) alginate monomers, (b) chain...

Alginates are made up of long chains of two monomers guluronic acid and mannuronic acid. The chains can be made of all one monomer or mixtures of both. The stems of kelp are made of chains with more guluronic acid, and the leaves (fronds) have more mannuronic acid. Guluronic chains bind tightly to calcium in mannuronic chains the calcium is more easily replaced by sodium, allowing the fibers to swell easily. 

A variety of organic adhesives which are capable of forming strong bonds between a polymeric (acrylate) restoration and the hydrophilic tooth material have recently been developed. A number of these monomers, which possess a pendent ionizable group, are polymerized in the mouth to form an adhesive layer. Alginates, which are used as impression materials, are formed by the reaction of the sodium salt of anhydro-beta-d-mannuronic acid with calcium sulfate. Calcium ions crosslink the linear polymer to form a gel. This reaction is carried out inside the mouth, and the gel formed retains the shape of the oral cavity. 

Coagulants and coagulant aids iron and aluminum sulfates, activated silicates, alginates, synthetic polyelectrolytes and their impurities, silica, and aluminum electrolyte monomers. 

The monomers of alginate are mannuronic (M 1) and guluronic(G 2) acids, the polymers being composed of three types of sequence homo-... 

Keywords Alginate, Depolymerization, Mannuronate monomers, OUgomannuro-nates. Surfactants... 

The same procedure of catalyst synthesis applied to other polysaccharides, such as -carrageenan and chitosan, allowed data on the influence of the chemical structure of the support to be obtained. The differences in turnover numbers (moles of product per moles of Pd per hour), close to 500 for alginates, 190 for carrageenan, and only 40 for chitosan, indicated that the activities were correlated to the electrostatic properties of the support. Carrageenans only bear one sulfate group per two saccharide monomers, while alginate presents one carboxylic group... 

Alginates are composed of (1—>4)-linked (3-D-mannuronic acid (M units) and a-L-guluronic acid (G units) monomers (Figure 16.9), with different sequential distribution along the polymer chain [142]. The composition, sequence, and molecular weight generally determine the physical properties of alginate [143]. 

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