Microwave-induced synthesis of partially aromatic polyamides via the Yamazaki phosphorylation reaction

Microwave irradiation was successfully applied to condensate aromatic diami nes with linear aliphatic dicarboxylic acids through the Yamazaki phosphory lation reaction. Succinic, adipic, suberic, sebacic, and fumaric acids were reacted with p-phenylenediamine or 2,5-bis(4-aminophenyl)-3,4-diphenylthio phene to produce P-series and T-series of partially aromatic polyamides. Me dium to high yields (60-100%) were achieved after a very short polymerizati on time (30 or 40 s). The intrinsic viscosity of products range from 10 to 80 mL g(-1). The solubility of the T-series of polyimides has been improved due to the presence of the bulky phenylated diamine moiety. The chemical s tructure of the polyamides was confirmed by FTIR, H-1 and C-13 NMR spectros copy. Thermal properties were investigated using DSC and TGA techniques und er inert atmosphere. Polyfumaramides (PF and TF) were recognized to be the most thermally stable polyamides (the highest IPDT values). However, these two polymers as well as polysuccinamides (P2 and T2) showed the lowest inde x of intrinsic thermal stability (ITS), i.e., although they have the highes t refractoriness (the highest char yields), they began to decompose at rela tively low temperatures. A crosslinking mechanism was proposed for the simi lar thermal behavior of the fumaramides and succinamides.