Direct Synthesis of Thermally Stable Semiaromatic Polyamides by Bulk Polymerization Using Aromatic Diamines and Aliphatic Dicarboxylic Acids

[Image: see text] Semiaromatic polyamides were directly synthesized by bulk polycondensation of aliphatic dicarboxylic acids (with 5, 6, 7, and 10 carbon numbers) and aromatic diamines (4,4′-oxydianiline and 4,4′-diaminodiphenylmethane) under natural pressure. In addition, copolyamides were successfully obtained by the copolymerization of aliphatic dicarboxylic acids, aromatic diamines, and biobased amino acid, 4-aminohydrocinnamic acid. The obtained polyamides had relatively high inherent viscosity values of 0.35–0.76 dL/g. The obtained polyamides exhibited good thermal stability with T(d5%) in the range of 316–416 °C, even when incorporated with aliphatic methylene units. In particular, some copolyamides (2AO, 2PO, and 2GM) had high T(g) values of 150, 158, and 156 °C and relatively low T(m) values of 277, 288, and 234 °C, respectively, which may be preferable thermal properties for melt-drawing processes.