Combination of Dynamic and Coordination Chemistry Achieving Two-Method Recycling of Polyurethane

Crosslinked polyurethanes (PUs) with excellent mechanical properties have been widely used, but they cannot be reprocessed or recycled for the lack of chain mobility. Here, aluminum acetylacetonate (ALA) is used as the crosslinker to construct a novel crosslinked PU with dynamic bonds and coordinated linkages. This type of PU demonstrates two different recycling methods, including thermal remolding and solvent recycling. Due to the thermally reversible reaction between β-diketone and isocyanate, the crosslinked PU can be reprocessed under the thermal treatment. On the other hand, the coordinated linkage in the polyurethane can provide the solvent recycling ability based on the dissociation of the coordinated bonds of aluminum acetylacetonate in an acid solution. Furthermore, the solvent recycling method can be used to selectively separate and recycle the crosslinked PU from polymer blends, which provides a novel method for reusing and recycling the polymer blends. Furthermore, aluminum acetylacetonate can be directly applied in the existing widely used PU systems to achieve a good ecofriendly loop to recycle the PU. This research exhibits a simple and general method for creating tailorable crosslinked PU materials with superior recyclability.