Prearranged polymers

MIP catalysts. Efendiev etal. have performed seminal research in which the oxidation of ethylbenzene to acetophenone was studied (Scheme I4).36a,37 Having copolymerized the diethyl ester of vinylphosphonic acid with acrylic acid, the resulting polymer was then functionalized with Co(II) complexes, while the template was added. A series of polymers were prepared in which the template was the substrate, an analog of the intermediate, or the product itself. Cross-linking of the prearranged polymer was effected using /V,/V-methylenebis(acrylamide), and a control polymer was prepared which did not contain imprinted sites. The substrate-imprinted polymer displayed a catalytic... 

For the crosslinked polyethyleneimine the distribution coefficients of the non-prearranged polymer between Cu and Ni is 7.8, whereas for the Cu(II)-prearranged polymer the value is 6.25, and the Ni(II)-prearranged polymer the value is 0.9 which shows different selectivity in metal ion uptake. Catalytic activities for oxidation reactions were investigated. 

The conformational prearranged effect of both the macromolecular ligand with respect to a certain metal ion and the active sites of metallopolymer catalysts to a substrate was observed in liquid-phase oxidations of alkylaromatic hydrocarbons recently the same was found in the case of hydroxyarenes [135-137]. Initially, a soluble metallocomplex is formed in the presence of metal ions or substrate. A structural rearrangement, specific to the reacting compounds, is further fixed in the process by cross-linking of the polymer support by AA -methylenediacrylamide with a subsequent removal of pattern substrates from cross-linked formations. Such an approach leads to a substantial increase of selectivity and activity of the catalyst in comparison with a catalyst obtained without directed generation of its structure. 

Valignat [54] demonstrated that this powerful assembly method could be used to lock reversibly directed assembled (with optical tweezers) microspheres grafted with complementary polymer brushes into a prearranged suprastructure (see Fig. 10). 

Efendiev, A.A. Kabanov, V.A. Selective polymer complexons prearranged for metal ions sorption. Pure Appl. Chem. 1982, 54, 2077-2092. 

Figure 23-3. Arrangement of cooperatively operating catalytic positions in (A) graft copolymers (B) random copolymers and (C) conformationally prearranged (before introduction into polymer) groups.

The role of solvent in molecular imprinting is especially important in the prearrangement (noncovalent) approach. Solvent not only influences the polymer morphology (inner surface area and average pore... 

In order to calculate fl, determine the number of possible arrangements of the (i + l)th maicromolecule given the i previous ones are prearranged, and the fraction of occupied cells zi/m is assumed equal over the whole lattice as well as in its certain local place (the mean field approximation). This situation is valid for moderate (middle) polymer concentrations and, certainly, is not the case in dilute solutions. 

Molecular imprinting is a method for the synthesis of polymers with predeterminated selectivity for various compounds. This technique uses noncovalent prearrangement of functional monomers in the presence of the print molecules prior to the polymerization for the creation of highly specific binding sites. After polymerization the print molecules are washed out of the macroporous polymer matrix. The result is a polymer with recognition sites due to the shape of the print molecules. The proper arrangement of the functional groups in the polymer have the affinity for the print molecules. This fact leads to the restriction that the structure of the enantiomers, to be separated, must be very similar to these of the print molecules. 

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