The development of biobased high-temperature polyamides that simultaneously satisfy demanding thermal requirements and remain processable remains a persistent challenge. Here, we report a biobased alicyclic–aliphatic copolyamides (PA5C/56) synthesized from pentanediamine, 1,4-cyclohexanedicarboxylic acid (CHDA), and adipic acid. The content of the rigid CHDA-derived “5C” unit was systematically varied to study its influence on solid-state polymerization (SSP) kinetics, thermal properties, and nanomorphology. While an increased 5C content effectively elevates the melting point and thermal stability, it significantly suppresses the molecular-weight buildup during SSP. Through a combination of selective etching, X-ray scattering, and end-group analysis, we unveil that a higher 5C fraction promotes the formation of denser and more finely dispersed crystalline lamellae. These lamellae function as “mesoscopic anchors,” which physically constrain the mobility of the amorphous chains, thereby reducing the collision probability of reactive end groups and decelerating the SSP kinetics. This work establishes a direct microstructure-mediated link between copolymer composition, chain-growth kinetics, and ultimate properties, offering a fundamental principle for rationally balancing thermal performance with polymerization processability in sustainable high-performance polymers.
Zhou et al. (Mon,) studied this question.