One-pot synthesis of copolyamide PA MXDT-MXD6 towards oxygen-barrier and high-temperature transparent applications.

[Display omitted] • A cost‐effective copolymerization strategy simultaneously achieves high‐temperature transparency and oxygen barrier properties. • Copolymers have superior activation energy of pyrolysis and lifetime. • The transparency of films (92%) is unaffected by thermal crystallization. • The oxygen‐barrier performance of copolymer films is increased by 32% compared to MXD6. Semi-aromatic polyamides have long been recognized for their exceptional comprehensive properties in numerous demanding applications. Among them, poly(m-xylylene adipamide) (MXD6) was commonly used in oxygen-barrier packaging but suffered diminished transparency due to thermal crystallization. Herein, we introduced terephthalic acid (PTA) as rigid monomer units into the chain of MXD6 to prepare amorphous copolyamides PA MXDT-MXD6 via one-pot polycondensation, guided by thermal analysis. The chemical structure of copolyamides was confirmed using 1H NMR and FTIR spectra. Thermal analysis revealed that the copolyamides exhibited high thermal stability, amorphous characteristics, and improved glass transition temperatures (110.9–136.5 °C). Pyrolysis kinetics further demonstrated that copolyamides have enhanced thermal stability and lifetime. Furthermore, copolymerization resulted in numerous amide bonds conjugated with benzene rings, leading to superior high-temperature transparency, oxygen-barrier, and mechanical properties compared to MXD6 and other reference polyamides. These characteristics indicate the potential suitability of copolyamides as transparent and heat-resistant barrier materials. [ABSTRACT FROM AUTHOR]