Polyrotaxane in-situ copolymerization stretchable supramolecular hydrogels for photo-controlled cascade energy transfer

Amphiphilic polysorbate (Tween 80) encapsulated hydrophobic methyl acrylate (MA), spiropyran (SP), nitrobenzoxadiazole (NBDAE) and cyanine 5 (Cy5) was mixed to form micelles, which in-situ copolymerized with acrylamide (AM) and polyrotaxane (PR) containing polyethylene glycol (PEG) threaded into vinyl modified α-cyclodextrin (α-CD) with amantadine end-capping to form stretchable supramolecular hydrogel. Benefiting from the sliding cross-linking points of PR, the hydrogel exhibited excellent mechanical properties (1300 % breaking strain and 0.26 MPa breaking stress). Meanwhile, photoreactive achievement of reversible SP acted as primary energy acceptor tuned cascade energy transfer from energy donor NBDAE to secondary acceptor Cy5 (energy transfer efficiency = 80 % for primary transfer, 65 % for secondary transfer). Therefore, this stretchable supramolecular hydrogel material can achieve phototunable multi-color emission and be applied in the field of time-resolved information anti-counterfeiting.