Macroporous polymer beads structure

Macroporous polymer beads, synthesized by suspension polymerization, are a class of polymer beads containing a permanent, well-developed porous structure in a dry state and having a wide range of applications—such as support for catalysts, immobilization of enzymes, HPLC columns, liberation of active substances, or adsorbents. 

Due to their highly developed porous structure, macroporous polymers become completely wetted with toluene within a few seconds. Simultaneously, the bead sUghdy expands. Afterward, a slower expansion takes place, where, probably, the highly crossUnked polymeric phase... 

The spectrum of commercial adsorbents for use in air pollution control also includes beaded, hydrophobic adsorber resins consisting of nonpolar, macroporous polymers produced for the specific application by polymerizing styrene in the presence of a crosslinking agent. Crosslinked styrene divinylbenzene resins are available on the market under different trade names. Their structure-inherent fast kinetics offers the advantage of relatively low desorption temperatures. They are insoluble in water, acids, lye and a large number of organic solvents. 

Resin beads are synthesized as gel or macroporous materials. The macroporous resins are polymerized in the presence of a third component that is insoluble in the polymer. After this insoluble component is removed, large pores remain that allow the ions to have improved access to the interior pore structure of the beads. Macroporous resins can be useful for large ions like proteins, but they are more expensive, have lower capacity, and are harder to regenerate than the gel resins. However, they are said to be more resistant to thermal and osmotic shock as well as to oxidation and organic fouling than the gel-type resins [4]. 

On the other hand, water does not plasticize the polymer phase of the macroporous XAD-4 sample therefore, the deformation of the rigid structure of the bead during drying from water has an elastic reversible character... 

S.3.2.2.4 Hard Templating by Polymers Another option for the synthesis of hierarchical zeohtes is the apphcation of polymers as hard templates, a strategy closely related to the use of carbons as hard templates. Several polymers have been used for this purpose. For example, polystyrene beads have been employed for obtaining hierarchical zeolites with a microporous/macroporous structure [161]. 

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