Controllable Depolymerization and Recovery of Interlocked Covalent Adaptable Networks via Cascading Reactions of the Built-In Reversible Bonds

A novel strategy for controllable depolymerization and recovery of polymer blends is proposed. The core advance lies in the application of reversible boronic ester bonds and imine bonds, which possess the abilities of correlative scission and rebuilding. Accordingly, reversibly interlocked polymer networks (RILNs) are prepared from two preformed crosslinked polymers, which respectively carry the two reversible bonds. By taking advantage of the intimate packing of the macromolecules from the two networks in the RILNs, the cascading effect between boronic ester bonds and imine bonds is enabled. When the dimethylformamide swollen RILNs are triggered by a little water, the boronic ester bonds in one component network are decomposed, affording boronic acid, which subsequently catalyzes the cleavage of the adjacent imine bonds in the other component network. Meanwhile, scission of the imine bonds also promotes decomposition of the boronic ester bonds as well. The cascading processes can be reversed via dehydration-induced reformation of boronic ester bonds. Hence, RILNs are allowed to be depolymerized in a controlled manner and then recovered by removing the solvent and water.