Polycondensation stepwise approach

The kinetics for stepwise polycondensation reactions and the kinetics for monofunctional aminations and esterifications are similar. Experimentally, both kinetic approaches are... 

The principle of the second synthetic approach to polycatenanes, i.e. stepwise polycondensation, has been proposed by Shaffer and Tsay, but not experimentally demonstrated [42, 43], This approach has the advantage over multifunctional polycondensation that a linear polymer is formed before cyclization (Scheme 7). However, the second step, which consists of the cyclization of n macrocycles along the polymer chain 19, is likely, again, to give rise to an undefined network, containing some rotaxane and catenane units 21, similar to the multifunctional polycondensation approach. 

An experimental attempt towards polycatenanes 9, based on a strategy related to the stepwise polycondensation approach, was reported in the seventies. Karagoumis et al. took advantage of the interface between a nonpolar phase (air, CC14) and a polar phase (H2O, Hg) to orient alkanes a,oj-disubstituted with polar groups (Scheme 9) [45], The successive addition of macrocycles of ring sizes 15-60 atoms and of difunctional species, susceptible to reaction with the a,o>disubstituted al-... 

There are numerous examples of the use of extruders to carry out chemical reactions in polymeric systems (Xan-thos, 1992). In genial, two types of reactions are carried out in extruders polymerization or depolymerization and polymer modification. In this section we illustrate the approach to modeling reactive extrusion by considering the stepwise polycondensation reaction of two species A and B in a singlescrew extruder. 

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