Template Copolycondensation

Copolymerization can be conducted stepwise (template copolycondensation), copolyaddition, radical or ionic copolymerization, ring-opening copolymerization, etc. 

A good example of template copolycondensation has been described by Ogata et al Copolycondensation of 2,6-dimethyl pyridine dicarboxylate and dimethyl adipate with hexamethylene diamine was carried out in the presence of polysaccharide - Pullulane (mol. weight 30,000) used as a template. The reaction was carried out in DMSO at 60 C. It was found that the content of 2,6-dimethyl pyridine dicarboxylate units in the copolyamide, determined by NMR analysis, increased in the presence of Pullulane in comparison with the amount obtained in the absence of the template. This effect can be explained by preferential adsorption by the template of monomer having pyridine groups in comparison with the adsorption of dimethyl adipate. A set of experiments was carried out under the same conditions, but in the presence of poly(acrylonitrile) instead of Pullulane. The composition of copolyamides was the same as in copolycondensation without the template. 

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Only a few publications have appeared in the literature on template copolycondensation, in spite of the fact, that the process is very important to understand the mechanisms of processes similar to natural synthesis of biopolymers. General mechanism of this reaction can be considered in terms of the examples of template step homopolymerization. A few published systems will be described in the Chapter 5. 

In principle, template copolymerization can be realized according to different reaction types as template copolycondensation, template copolyaddition, ring-opening copolymerization, and radical or ionic copolymerization. However, radical template copolymerization is slightly more elaborated. The process of template copolymerization can be classified from the point of view of stmcture of the template. We can make a distinction between two cases whether the template is a homopolymer or a copolymer. An important role in the process of template copolymerization plays a difference in interactions between the template and two comonomers. 

In our work, the process of template copolycondensation was the subjed of an investigation using urea and thiourea as co-reagents. It was expected that, similar to the reaction described by Papisov, copolycondensation in the presence of PAA woidd proceed according to Scheme 14. 

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