The effect of polymerization methods on the molecular chain structure and properties of high-temperature resistant terpolymer polyamide

PA6T/66 copolymer can be synthesized by various polymerization methods. Nevertheless, the effects of different synthetic routes on molecular chain structure, as well as the subsequent correlation with performance, remain unclear. In this work, three polymerization strategies, melt polymerization (MP), prepolymerization coupled with solid-state polymerization (Pre-SSP) and direct solid-state polymerization (DSSP), were employed to prepare PA6T/66 with comparable molecular weights and identical monomer compositions. The influences of polymerization methods on chain sequence structure were systematically characterized and calculated via 1 HNMR spectroscopy. Combined with molecular dynamics (MD) simulations, the effect of molecular chain structure on intermolecular interactions and chain conformations was also investigated in depth. Furthermore, the relationship between molecular chain structure and the thermal and mechanical properties of the copolymer was established. Results demonstrate that PA6T/66 prepared using the DSSP method exhibits longer 6T and 66 segments, higher crystallinity and a more perfect crystal structure, thus endowing it with outstanding mechanical strength and thermal properties. Therefore, the findings of this study will provide critical guidance for regulating the structure and properties of polyamides.