Sustainable Long-Spaced Polycondensates toward Polyethylene-Like Materials

Long-spaced polycondensates generally refer to the synthetic polymers containing long methylene segments in repeating units, which are separated by functional groups such as ester, amide, and carbonate groups. Such polymers usually show the polyethylene-like crystallization behavior, mechanical property, processability, and also good chemical recyclability. Since most of the long-spaced polycondensates are highly crystalline, understanding the relationships between their chain structure, crystallization, and macroscopic properties is of fundamental importance for developing novel sustainable polymer materials. This Viewpoint focuses on discussing the crystallization and its relations to the chain structure, macroscopic performances (e.g., thermal, mechanical, barrier properties) through the case studies on long-spaced polyesters and polyamides, followed by a brief review on other long-spaced polymer families. Then, chemical recycling of long-spaced polycondensates is also commented. Finally, a conclusion of the Viewpoint and an outlook for future directions are shared. We hope that this Viewpoint can provide inspiration for future studies on advanced sustainable polymers.