Hyperbranched Aromatic Polyamides Prepared by Direct Polycondensation

Hyperbranched aromatic polyamides and copolymers were prepared by direct polycondensation in the presence of condensation agents. Three strategies were described: (1) self-polycondensation of AB x-type monomers, (2) copolymerization of AB2 and AB monomers and (3) polymerization of A2 and B3 monomers. The self-polycondensation of AB x monomers proceeded without gelation to form soluble powdery polymers. The degree of branching of the hyperbranched polyamides was greatly influenced by the structure of the monomers. Copolymerization of AB2 and AB monomers allowed control of the branching density of the resulting polymers. Spectroscopic measurements revealed that the copolymers were composed of five kinds of repeating units. The good solubility and adequate solution viscosity of the copolymers allowed the preparation of transparent yellow films by casting the copolymer solution onto a glass plate. The polymerization of A2 and B3 monomers was also investigated as a novel route to prepare hyperbranched polyamides without using AB x-type monomers. Gelation during the polymerization could be avoided by the optimization of the reaction conditions. The structure and properties of the resulting polymers were compared with the hyperbranched polyamide prepared from the corresponding AB2 monomer.