Single-stage polycondensation

Recently Hay and co-workers developed a method for preparing PNI that involves the use of a monomer containing imide rings [67]. The reaction of hydrazine with DNTA proceeds in a similar fashion to that in Scheme 1.4 and yields bis(aminoimide) that reacts with 2,2-bis([4-(3,4-dicarboxyphenoxy)phenyl]propane (dianhydride A) in an m-cresoho-dichlorobenzene mixture under the conditions of the single-stage polycondensation to produce poly(ether naphthalenecarboximide) (PENI) (Scheme 1.14) ... 

About 40-70 mol% of the compound of formula Ac-n-CgH COOH are used to produce complex polyesters of high mechanical strength [45], The polyesters with improved physic-chemical characteristics can be obtained by single-stage polycondensation of the melt of 30-60 mol% of -oxyben-zoic acid mixed with other ingredients [46],... 

The second method is a high-temperature, single-stage polymerization (Figure 5.24) that involves a polycondensation of bis(o-aminophenol)s with aromatic dicarboxylic acids or dicarboxylic acids... 

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