【Polymer】Pseudo eutectic of isodimorphism to design semi crystalline copolyamide with high transparency, solvent resistance, and mechanical ductility
writer：Yanlin Liu , Kejian Yang , Wanding Chen , Zhaobin Tang , Xudong Chen
keywords：聚酰胺、結晶、高透明、耐溶劑性
source：期刊
Issue time：2024年
Transparent polyamide has excellent optical transparency and stress cracking resistance, making it the preferred material for smart wearable electronic devices and new energy vehicle displays. However, traditional transparent polyamides are designed based on amorphous aggregation structures with large steric hindrance or side groups, which have drawbacks such as poor resistance to polar solvents and insufficient ductility. In this regard, we innovatively proposed a strategy to achieve high transparency, mechanical strength and ductility, and resistance to polar solvents for isodimorphism copolyamides by regulating their chemical structures through pseudo eutectic points. Copolyamides PA5T/5X were synthesized with various copolymerization compositions and ratios, with the PA5T/56 series exhibiting isomorphism properties and the PA5T/58, PA5T/510, and PA5T/512 series exhibiting isodimorphism properties. Due to the comonomer exclusion/inclusion balance between the copolymerization units 5T and 5X, the smallest crystallite size and loosest interface between the crystalline and amorphous regions at the pseudo eutectic in the isodimorphism systems weaken light reflection and refraction, resulting in excellent transparency, ultra-high fracture elongation (>200 %), and polar solvent resistance of the copolymers. This molecular design strategy for regulating the isodimorphism structure of random copolymers will provide a new method for synthesizing copolyamides with the required comprehensive performance.