Polyolefin Blends with Co-Continuous Architectures Enabled by Dynamic Covalent Crosslinking

Blending polymers produces brittle materials due to macrophase separation and poor interfacial adhesion, which is exemplified by mixtures of polyolefins. This presents a formidable challenge for the mechanical recycling of mixed plastic waste. Here, we show that dynamic covalent crosslinking of immiscible polyolefin blends at their interfaces and within the bulk creates co-continuous architectures that enhance stress transfer, toughness, and amenability to mechanical reprocessing. Along with morphological changes and reductions in crystallite size, 4D-STEM imaging revealed shear-induced alignment of crystallite planes with strong orientational preference, particularly at polymer–polymer interfaces, contributing to advantaged blend performance. We further demonstrate that changes in crosslinker density and valency allow the properties of binary and ternary polyolefin blends to be tuned in a modular fashion from widely available polymers.