Multicomponent polymers, preparation requirements

In principle, the broad range of functional monomers eurrently available makes it possible to design an MIP specific for any type of stable ehemical compound. Currently the selection of the best monomers for polymer preparation is one of the most crucial issues in molecular imprinting. Thermodynamic calculations and combinatorial screening approaches olfer possible solutions, and have already been used successfully for predicting polymer properties and for the optimization of polymer compositions (see Ref. 9,57,58, and Chapter 8), however, in practical terms, application of these methods is not trivial. The problem lies in the technical difiiculty of performing detailed thermodynamic calculations on multicomponent systems and the amount of time and resources required for the combinatorial screening of polymers. To check a simple two-component combination of 100 monomers, for example, one has to synthesize and test more than 5000 polymers, a very difiicult task. This task will be further complicated by the possibility that these monomers could be used in monomer mixtures in dilferent ratios. 

Quantification requires knowledge of the beam path through the sample. Hence, the sample often needs to be modified to allow for a known geometry. Spectral subtraction, least square regression analysis, PLS and spectral deconvolution are some of the spectroscopic techniques widely used to quantify constituents in a multicomponent sample. For almost any type of spectroscopic analysis, this is usually the first step. It is especially important for polymers given the variations in spectra for the same polymer due to molecular weight, conformation, crystallinity, sample preparation, age and sampling method. 

As described in the previous section, the formation of highly ordered multicomponent supramolecular systems can be hampered by the dynamics of the mixture. This observation motivates to take advantage of kineticaUy stable structures to prepare the desired complex multicomponent systems. For example, a supramolecular polymer of molecules A can be used as a nucleation site for the self-assembly of compound B in a subsequent step. This synthetic pathway requires that the aggregates formed at each step are kinetically stable under experimental conditions. 

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