Direct Polycondensation

The concept of the direct polycondensation is introduced. The direct polycondensation of dicarboxylic acids with aromatic diamines in the presence of condensing agents produced polyamides with high molecular weights under mild conditions and in excellent yields. Various condensing agents were successfully used in a chemoselective fashion with dicarboxylic acids and diamines, without special protection of the acyl-sensitive groups. Chemoselectivity was demonstrated in sequential polyamidation; the synthesis of regular polyamides from both symmetric (YccY) and nonsymmetric (XabX) monomers. A dehydrating agent, phosphorus pentoxide-methanesulfonic acid (PPMA), was also found to be a useful condensing agent for the preparation of condensation polymers,such as poly(ether-sulfone), poly(ether-ketone) along with a number of heterocyclic polymers: poly(benzimidazole), poly(benzothiazole) and poly(benzoxazole). 1. Introduction 2. Concept of Direct Polycondensation 3. Synthesis and Reaction of Condensing Reagent 4. Chemoselective Polyamidation 5. Synthesis of Sequential Polyamide 6. Synthesis of Condensation Polymers in PPMA 7. Summary and Outlook