Modulating the Crystallinity of a Circular Plastic towards Packaging Material with Outstanding Barrier Properties

Chemically recyclable polymers have attracted increasing attention since they are promising materials in a circular economy, but such polymers appropriate for packaging applications are scarce. Here a combined thermal, mechanical, and transport (permeability and sorption) study is presented of a circular polymer system based on biobased trans-hexahydrophthalide which, upon polymerization, can lead to amorphous, homochiral crystalline, and nanocrystalline stereocomplex materials. This study uncovers their largely different transport properties of the same polymer but with different stereochemical arrangements and synergistic or conflicting effects of crystallinity on transport properties versus thermal and mechanical properties. Overall, the homocrystalline chiral polymer shows the best performance with an outstanding barrier character to gases and vapors, outperforming commercial poly(ethylene terephthalate) and polyethylene. The results presented herein show that it is possible to modify the crystalline structure of the same polymer to tune the mechanical and transport properties and generate multiple materials of different barrier characters.