Disulfide-based poly-pseudorotaxanes with locked and on demand unlocked degradability

Materials containing labile linkages are in great demand due to their inherent degradability and recyclability. However, this generally comes at the cost of their stability during a use phase and synthesis. Here we present a concept of supramolecular polymers with locked and on demand unlocked labile linkages, rendering the materials robust yet degradable. We designed disulfides with polymerizable handles forming inclusion complexes (pseudorotaxanes) with cucurbit[6]uril (CB6) macrocycle positioned specifically around the disulfide bond. CB6 endowed the disulfide group with significantly improved photo-, thermo- and chemical stability. The polymerization of these monomers delivered poly-pseudorotaxanes with locked disulfide bonds. pH-triggered removal of the ionic host-guest interactions allowed for the dissociation of the poly-pseudorotaxane into the unlocked polydisulfide, amenable for further degradation, and CB6 in its free form. The former was subsequently depolymerized into dithiols under mild reduction of disulfide bonds.