Microporous polymers, reagent

Distribution of Active Sites. If the chemical reaction that functionalizes the polymer proceeds slower than diffusion of the reagent into the polymo, functional groups will be distributed uniformly throughout the particle. If chemical reaction proceeds faster than diffusion, the polymer be is functionalized first at its surface, and the reaction proceeds into the bead 1 a shell (Ufhisive mechanism 1241. Partial conversion, shell diffusive reactions give particles functionalized predonunantly near the surface. The progress of shell diffusive rations in microporous polymers can be observed with beads under a microscope. 

Reactions with insoluble polymeric reagents are conducted as stirred mixtures in the same manner as reactions with soluble reagents. A microporous polymer usually is swollen for efficient use. Macroporous PS and SG with lipophilic surfaces may require wetting with a water miscible organic solvent before use in water. After reaction the polymer usually is filtered with a glass frit. The frit can... 

Hi. The monomer polymerization route. Compared with the resin-functionalization route, the homo- and copolymerization of organotin-containing monomers permits one to influence the polymer resin structure to a greater extent. In principle, it is possible to prepare gel-type, macroporous, microporous or nonporous polymers. The pore structure, tin loading, solubility and other factors which influence the reactivity of the polymer-supported organotin reagents can be controlled by appropriate... 

Most polymeric redox reagents have been developed on microporous polystyrene, typically cross-linked with 1% divinylbenzene. Few examples have been reported for macroporous polystyrene, silica or other supports such as high-loaded cross-linked polyethylene imine (Ultraresins). Some problems specific for redox reactions can also arise from the reactivity of the polymer support itself. In cross-linked polystyrene, for example, benzylic positions can be oxidized at elevated temperatures and thus can account for a competing reaction pathway [8], Further reactivities are found for other solid supports as well. 

The Ca2+-sensitive chromoionophore Chlorophosphonazo III was physically immobilized on the PTFE polymer track membrane with micropore diameter of 0.2 pm. The PTFE foil was dipped into satured methanolic solution of the reagent and after a few seconds of soaking the foil was washed with distilled water to remove this part of the reagent, which has not been immobilized in the sensing layer. It was found that to immobilize a greater amount of the indicator the foil should be conditioned in an acid solution before treatment with the reagent. Results... 

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