Linked Organic Polymers

The resins used are highly cross-linked organic polymers with acidic functional groups. The most common of the resins used are sulfonated copolymers of styrene and divinylben2ene (see Ion exchange). 

The ion movement can be controlled by ion exchange or ion transfer membranes, thin sheets of cross-linked organic polymers with ion exchange properties—for example, sulfonated polystyrene-divinylbenzene polymers. Both cation-permeable and anion-permeable membranes are available and have been described (3, 9). To achieve demineralization, these membranes are spaced alternately between a cathode and an anode which introduce direct current. The compartment between each pair of membranes is filled with a saline water. The resulting ion motion is controlled by the membranes, so that one set of compartments—for example, the even-numbered compartments—lose ions and the odd-numbered compartments gain ions. The product from the ion-losing cells is collected and comprises electrically demineralized water. 

Size separation columns are available with silica, zirconium, and heavily cross-linked organic polymer backbones. The polymer columns show the same pressure and solvent fragility described for ion exchange columns. Silica size columns must be protected from pH changes like partition columns, which must be used with a pH between 2.5 and 7.5. Zirconium columns are not pH or temperature sensitive, but possess chelation properties that must be chemically masked to prevent interference with the size separation. 

Another notable difference between imprinted artificial antibodies and natural antibodies lies in the fact that imprinted polymers are classified as cross-linked organic polymers, generally insoluble in common solvents. This characteristic feature makes them attractive and advantageous for application in analytical and separation technology, because imprinted polymers can be used as affinity materials... 

Reversed phase packings Non-polar Reversed phase silicas with n-alkylsilyl groups, reversed phase silicas with hydro-phobic polymer coatings, hydrophobic cross-linked organic polymers, porous carbon Aqueous/organic mobile phases... 

Dynamic spectroscopy (this method is more sensitive to Tg modifications) characterized cured MTI as polymer networks. The existence of the high-elasticity plateau typical for cross-linked organic polymers makes it possible to determine values of high elastic modulus in the pseudoequilibrium zone. Systems based on oligoethers and mixtures with oligoesters are characterized by E values of 5.0 and 8.5 MPa, respectively, which comply with adhesion strength data. 

Figure 1 The high cross-linking density of silica gives it much greater mechanical stability than cross-linked organic polymers.

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