Rigid Polyamide Networks and Fractal Polymers Prepared in Solution by Other Procedures

2 Rigid Polyamide Networks and Fractal Polymers Prepared in Solution by Other Procedures 

In addition to the above described polycondensation of free carboxyhc add with aromatic amine in the presence of aryl phosphites, there are three more amideforming polycondensations described in the literature. In contradistinction with the phosphite reactions, these require the use of an activated form of the carboxy acid, such as acid chloride. Similar to the phosphite reactions, these reactions are also conducted in aprotic amide solvent such as DMAc or NMP, in the presence or absence of solubilizing salts such as LiCl or CaCl2. 

The first of these procedures is the well-known Schotten-Bauman reaction [403-408] in which an AA monomer such as di(add chloride) is allowed to react, in the presence of an organic base, with a BB monomer such as aromatic diamine to form a polymer. 

When either or both of the comonomers has a functionality higher than 2, a branched system evolves. The major limitation of the Schotten-Baumann reaction is its uses of AA and BB-type monomers, to the exclusion of AB-type monomers. This is simply due to the general unavailability of AB-type monomers in which A is an acid chloride and B is a free amine. Responding to the need, a procedure was developed over the years at duPont by which a reactive AB-type monomer is first prepared and then reacted with itself to create linear [210, 414, 415] or highly branched [416] aromatic polyamide polymers. Accordingly, an amino acid chloride hydrochloride (e.g.,) 

In the reported procedure [416], the desired products were aromatic FPs and not an infinite network, leaving the number of acid chloride and amine groups unequal in each preparation. As with the work of Aharoni [350,413], this led to the FPs being decorated, essentially on their exteriors, with the reactive group present in excess. 

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