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

Abstract

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 βdiketone 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.

Photodegradable Dynamic Polyurethane Networks via Dithioacetals

“…It could be understood by the fact that the rigid phenolic carbamate groups in DAV-based PUNs contributed more to the mechanical properties than the urethane groups generated by the flexible alkyl hydroxyl group in DAH. The observed mechanical properties are within the range of reported PTHF/HDI-based PUNs, where trifunctional or tetrafunctional cross-linkers were utilized in a similar manner (Table S3 for the summarized mechanical properties and Figure S8 for the chemical structures of cross-linkers). − …”

Recycling of polyurethanes: where we are and where we are going

“…Their results indicate that waste PU foams can be directly recycled into a new foam while preserving its structural properties and chemical integrity. Bai and co-workers 129 exploited the combination of coordination and dynamic chemistry for facilitating the thermal and chemical recycling of polyurethanes. A general scheme is shown in Fig.…”

Complexation of heavy metal cations with imidazolium ionic liquids lowers their reduction energy: implications for electrochemical separations

“…1,2 Different chemical functional groups, stereoisomers, or other structural features affect the coordination chemistry of product complexes by altering the speciation environment, including the steric and electronic characteristics of ligands. [3][4][5] Speciation of ionic liquids (ILs) is a good example that has attracted broad interest due to the unique molecular capabilities of ILs to trap targeted molecules. 6,7 Due to the tunability of the chemical and physical properties of ILs through selection of various anion/cation combinations, an extraordinarily diverse combination of speciation possibilities, with potentially distinct geometric and electronic features, is feasible.…”